Low-dose Methylphenidate Research Articles

The importance of including ADHD in the differential diagnosis in adults. About a case

IntroductionADHD is a diagnosis almost always made in childhood or adolescence and oftent difficult to make it new in adults because it is not thought of in the differential diagnosis process and for the lack of experience from adult devices. -ADHD in adults is characterized by symptoms of executive dysfunction, inattention, emotional dysregulation. The symptoms of impulsivity and hyperactivity tend to be less evident.Objectives-Frequently, the adult patient with ADHD comes to the consultation with a secondary symptom and the primary pathology is hidden and often not evident at first glance.Methods-A 20-year-old woman, university student, with no relevant medical or psychiatric history, without toxic habits, who attended her first consultation referred by her primary care physician for long-standing insomnia, restless legs and anxiety.-The patient’s underlying complaint and her bigger concern is her poor academic performance. It is striking that she has just started her third year at the university, the first year she did not pass any subjects, the second year she changed majors and only passed two, now she is repeating the course.-The examination did not reveal overt affective symptoms, nor psychotic symptoms or other notable psychopathology. The patient’s speech tended towards superficiality, inconcretion, it was salty, it was difficult for her to express herself, even suggesting a certain intellectual disability.-In the first consultation sleep study is requested. And referral to clinical psychology consultation for psychometric study.Results-She is administered Clinical interview and WAIS IV (Adult Intelligence Scale), Trail Making Test, d2 and Stroop, Diagnostic Interview for ADHD in adults (inattention items).-The WAIS-IV demonstrated global cognitive abilities within normality, although with significantly lower scores in the IMT and IVP indices which involve the functions of attention, concentration, mental control and short-term visual memory). Trail Making Test, d2, Stroop and Diagnostic Interview of ADHD in adults (inattention items) yielded profile results highly suggestive of Attention Deficit Disorder without Hyperactivity.-The insomnia subsided with a regimen of 7.5 mg of mirtazapine per day. Subsequently, after starting treatment with low-dose methylphenidate (20 mg/day), the patient improved very significantly, both academic performance and social functioning and mood, self-esteem and subjective well-being.Conclusions-We must always include ADHD in the differential diagnosis of a young adult patient when faced with a wide variety of consultation symptoms, especially if they report some type of deterioration or dysfunction in their social, family or academic life.-An adequate clinical evaluation supported, if possible, by psychometric tests is essential to reach the diagnosis, which allows establishing an effective treatment that modifies the patient’s overall prognosis.Disclosure of InterestNone Declared

Phasic dopamine signals are reduced in the spontaneously hypertensive rat and increased by methylphenidate.

The spontaneously hypertensive rat (SHR) is a selectively bred animal strain that is frequently used to model attention-deficit hyperactivity disorder (ADHD) because of certain genetically determined behavioural characteristics. To test the hypothesis that the characteristically altered response to positive reinforcement in SHRs may be due to altered phasic dopamine response to reward, we measured phasic dopamine signals in the SHRs and Sprague Dawley (SD) rats using in vivo fast-scan cyclic voltammetry. The effects of the dopamine reuptake inhibitor, methylphenidate, on these signals were also studied. Phasic dopamine signals during the pairing of a sensory cue with electrical stimulation of midbrain dopamine neurons were significantly smaller in the SHRs than in the SD rats. Over repeated pairings, the dopamine response to the sensory cue increased, whereas the response to the electrical stimulation of dopamine neurons decreased, similarly in both strains. However, the final amplitude of the response to the sensory cue after pairing was significantly smaller in SHRs than in the SD rats. Methylphenidate increased responses to sensory cues to a significantly greater extent in the SHRs than in the SD rats, due largely to differences in the low dose effect. At a higher dose, methylphenidate increased responses to sensory cues and electrical stimulation similarly in SHRs and SD rats. The smaller dopamine responses may explain the reduced salience of reward-predicting cues previously reported in the SHR, whereas the action of methylphenidate on the cue response suggests a potential mechanism for the therapeutic effects of low-dose methylphenidate in ADHD.

Open assessment of the therapeutic and rate-dependent effects of brain balance center® and interactive metronome® exercises on children with attention deficit hyperactivity disorder

The aim of this open study was to delineate domains of benefit and effect size measures to design an appropriately powered randomized control trial to assess the efficacy of Brain Balance@ exercises and Interactive Metronome@ training (BB/IM) on ADHD symptoms in children. Participants underwent an extensive 15-week, 5 time per week, at-home training program. Results were assessed in 16 youths with ADHD (14M/2F, 10.8±1.7 years) who completed the program and compared to 8 typically developing controls (4M/F4, 11.0±1.8 years). BB/IM was associated with a significant reduction of 8.3 and 8.2 points on the Conner's Parent Rating Scale – Revised and the ADHD Rating Scale – IV. BB/IM was not associated with improvement on the Quotient ADHD System but with rate-dependent effects on hyperactivity and attention that were similar to previously reported effects of low dose methylphenidate. Both therapeutic and rate-dependent effects were observed on the Tower of London. The study provides information that could be used to design a randomized control trial, which is required for proof of efficacy. A key limitation is that 59% of the 39 enrolled participants with ADHD dropped out of the study and a new study should include multiple ratings during the course of treatment.

Abstinence from Chronic Methylphenidate Exposure Modifies Cannabinoid Receptor 1 Levels in the Brain in a Dose-dependent Manner.

Methylphenidate (MP) is a widely used psychostimulant prescribed for Attention Deficit Hyperactivity Disorder and is also used illicitly by healthy individuals. Chronic exposure to MP has been shown to affect physiology, behavior measures, and neurochemistry. The present study examined its effect on the endocannabinoid system. Adolescent rats had daily oral access to either water (control), low dose MP (4/10 mg/kg), or high dose MP (30/60 mg/kg). After 13 weeks of exposure, half of the rats in each group were euthanized, with the remaining rats underwent a four-week- long abstinence period. Cannabinoid receptor 1 binding (CB1) was measured with in vitro autoradiography using [3H] SR141716A. Rats who underwent a 4-week abstinence period after exposure to chronic HD MP showed increased CB1 binding in several cortical and basal ganglia regions of the brain compared to rats with no abstinence period. In contrast to this, rats who underwent a 4-week abstinence period after exposure to chronic LD MP showed lower CB1 binding mainly in the basal ganglia regions and the hindlimb region of the somatosensory cortex compared to rats with no abstinence period. Following 4 weeks of drug abstinence, rats who were previously given HD MP showed higher [3H] SR141716A binding in many of the cortical and basal ganglia regions examined than rats given LD MP. These results highlight the biphasic effects of MP treatment on cannabinoid receptor levels. Abstinence from HD MP seemed to increase CB1 receptor levels, while abstinence from LD MP seemed to decrease CB1 levels. Given the prolific expression of cannabinoid receptors throughout the brain, many types of behaviors may be affected as a result of MP abstinence. Further research will be needed to help identify these behavioral changes.

Chronic treatment and abstinence from methylphenidate exposure dose-dependently changes glucose metabolism in the rat brain

Methylphenidate (MP) is extensively prescribed for attention deficit hyperactivity disorder (ADHD). While MP is effective in ameliorating symptoms of ADHD, MP is also used illicitly among healthy subjects without ADHD for cognitive-enhancing purposes. The deleterious consequences associated with long-term MP use as well as its cessation on brain activity remains to be understood. To address this, we administered either water, low dose MP (LD MP), or high dose MP (HD MP) to healthy adolescent Sprague Dawley rats, with five days on the treatment and two days off for thirteen consecutive weeks. Rats were then abstinent from their respective treatments for four weeks. Using positron emission tomography (PET) and fluorodeoxyglucose [18F] (FDG), we scanned rats at three time points: after thirteen weeks of treatment, after one week of abstinence, and after four weeks of abstinence. After thirteen weeks of LD and HD MP treatment, increases in brain glucose metabolism (BGluM) were seen in several cortical and subcortical regions associated with sensory and motor functions as well as learning and memory. One-week abstinence from LD MP treatment promoted increased BGluM compared to both water treated and HP MP treated groups. After four weeks of abstinence, little group differences were seen. Longitudinally, we observed contrasting differences on BGluM depending on whether a LD or HD of MP was administered. Our results demonstrate that MP treatment during adolescence can significantly alter BGluM. Moreover, these changes in brain activity do not subside in many areas of the brain after both one and four-week drug abstinence.

Functional MHCI deficiency induces ADHD-like symptoms with increased dopamine D1 receptor expression

Inappropriate synaptic development has been proposed as a potential mechanism of neurodevelopmental disorders, including attention-deficit hyperactivity disorder (ADHD). Major histocompatibility complex class I (MHCI), an immunity-associated molecule expressed by neurons in the brain, regulates synaptic development; however, the involvement of MHCI in these disorders remains elusive. We evaluated whether functional MHCI deficiency induced by β2m−/−Tap1−/− double-knockout in mice leads to abnormalities akin to those seen in neurodevelopmental disorders. We found that functional MHCI deficiency induced locomotor hyperactivity, motor impulsivity, and attention deficits, three major symptoms of ADHD. In contrast, these mice showed normal spatial learning, behavioral flexibility, social behavior, and sensorimotor integration. In the analysis of the dopamine system, upregulation of dopamine D1 receptor (D1R) expression in the nucleus accumbens and a greater locomotor response to D1R agonist SKF 81297 were found in the functional MHCI-deficient mice. Low-dose methylphenidate, used for the treatment of ADHD patients, alleviated the three behavioral symptoms and suppressed c-Fos expression in the D1R-expressing medium spiny neurons of the mice. These findings reveal an unexpected role of MHCI in three major symptoms of ADHD and may provide a novel landmark in the pathogenesis of ADHD

831 Diagnostic and Treatment Challenges in a Child with Type 1 Narcolepsy

Abstract Introduction The diagnosis and management of Narcolepsy can be challenging in young children. We present a case of abrupt onset severe type 1 narcolepsy complicated by tactile hallucinations with stimulant medication therapy. Report of case(s) A previously healthy 7-year-old African American female presented to us at the beginning of the current pandemic with one week of excessive daytime sleepiness (EDS) with associated enuresis, hyperphagia and two episodes of cataplexy. She also presented with hypnagogic hallucinations and dream enactment behaviors. She was extremely sleepy with a score of 24/24 on the Epworth Sleepiness Scale. Her neurological exam was negative except for facial twitching appearing to be cataplectic facies. Extensive work up including urine toxicology, serology and cerebrospinal fluid (CSF) tests were undertaken to rule out infectious and demyelinating conditions; the results of these tests were negative. Brain magnetic resonance imaging as well as electroencephalogram testing were unremarkable. Overnight polysomnography demonstrated short sleep latency and rapid eye movement (REM) sleep without atonia and a multiple sleep latency test showed a mean sleep latency of less than 2 minutes and 4/4 sleep onset REM periods, highly suggestive of narcolepsy. Her HLA DQB1*0602 haplotype was positive but CSF Hypocretin testing was not done. She was given a diagnosis of Narcolepsy type I and started treatment on low dose Methylphenidate and Venlafaxine to address her EDS and cataplexy, respectively. Her EDS was gradually controlled with a higher dose of Methylphenidate but she developed severe tactile hallucinations. She complained of feeling bugs crawling under her skin and could not keep her clothes on due to constant discomfort. The tactile hallucinations improved with discontinuation of methylphenidate but reappeared with introduction of a different class of stimulants. Modafinil was ineffective in controlling her EDS symptoms. Her EDS, cataplexy and enuresis were better controlled after starting her on Sodium Oxybate. She continues to suffer from moderate to severe EDS with optimally dosed Sodium Oxybate with suboptimal response to various typical and atypical stimulants. Conclusion This case illustrates the difficulties in diagnosing and treating pediatric narcolepsy patients and a unique challenge of tactile hallucinations with stimulant medications. Support (if any):

A Single Low-Dose of Methylphenidate Improves Abnormal Visual Field Testing

ABSTRACT Purpose To evaluate the effect of methylphenidate on visual field testing in healthy adults with abnormal visual field results. Methods This prospective, randomized, controlled interventional clinical trial comprised all patients who had abnormal visual field test results and normal eye examination and ophthalmic history. Eligible patients were randomly assigned to either the study group or the control group. All patients repeated their visual field testing. Study group patients received a single dose of 10 mg methylphenidate prior to that. The main outcome measures were the percent difference in mean deviation and pattern standard deviation between the second and first visual fields. Results The methylphenidate group had greater improvement in all parameters. Mean deviation improved by median 68% (IQR 19%–78%) in the methylphenidate group vs. 27% [−5% to 55%] in the controls. However, this was not statistically significant (p = .83). Pattern standard deviation improved by median 49% (22%–59%) vs. 7% [−9% to 45%], respectively (p = .012). The visual fields were also reviewed by 3 masked experienced ophthalmologists. They indicated that the second visual field improved in 76.2% of the methylphenidate group vs. 48.5% of the controls (p = .04). A normal repeat visual field occurred in 57.7% vs. 21.2%, respectively. A subgroup analysis of patients with prior experience in visual field testing yielded an even more striking improvement in the methylphenidate group vs. controls. Conclusions A single low dose of methylphenidate can improve visual field testing in subjects without ocular pathology, and even more in those with prior experience in perimetry.

Chronic oral methylphenidate treatment in adolescent rats promotes dose-dependent effects on NMDA receptor binding

AimExamine the effects of chronic oral Methylphenidate (MP) treatment on the N-Methyl-D-aspartic acid (NMDA) glutamate receptor binding in the rat brain using a previously established drinking paradigm that has been shown to deliver MP with similar pharmacokinetic profile as observed clinically. Main methodsBriefly, rats were divided into three treatment groups of water, low dose MP (LD; 4/10 mg/kg), or high dose MP (HD; 30/60 mg/kg). Following a 3-month treatment period, some rats were sacrificed while others went through an additional 1-month abstinence period before they were sacrificed. In vitro autoradiography (ARG) was carried out using [3H] MK801 to examine NMDA receptor binding in the brain. Key findingsThe dose-dependent effects of MP following 13 weeks of treatment on [3H] MK-801 binding were seen across the brain in the following regions: prelimbic, insular, secondary motor, primary motor, retrosplenial, rhinal, piriform, auditory, visual, dorsolateral striatum, nucleus accumbens core, hippocampus, amygdala, and thalamic regions. No differences were observed in [3H] MK-801 binding levels in animals that underwent the same treatment followed by a 4 week abstinence. SignificanceThese results demonstrate that chronic MP treatment altered NMDA receptor expression throughout the brain, which in turn may impact an individual's drug-seeking behavior, fear memory formation and overall activity. However, these effects of chronic MP were eliminated following cessation of treatment.

ADHD IN OLDER ADULTS: A CASE REPORT LITERATURE AND REVIEW OF THE

Introduction The prevalence of attention deficit hyperactivity disorder (ADHD) in older adults is estimated to be between 1.5 – 3.3 % across studies (Kooji et al, 2016). Older adults constitute a group in which ADHD is frequently underdiagnosed, undertreated, and often overlooked in both clinical practice and research. It is believed that older adults may have experienced longitudinal impact and a lifelong consequences of ADHD symptoms, in the absence of support for their problems in child- or adulthood (Michielson et al, 2015). Nadeau reported that age related cognitive changes, worsening physical health, and the lack of structure that often comes with retirement frequently tend to perpetuate symptoms of inattention (Nadeau, 2018). We present the case of an elderly man with ADHD. This will be followed by a review of the literature on ADHD in older adults. Methods Case of Mr. R: We present the case of Mr. R, a 75-year old man who presented for evaluation of cognitive complaints. He reported chronic difficulties with attention and concentration, with recent worsening of focus, attention, concentration, and memory. Assessment consisted of evaluation of the patient, collateral information from his wife, brain imaging, and neuropsychological testing. His presentation was felt to be consistent with chronic untreated ADHD, now superimposed with mild cognitive changes across other domains. A trial of low dose methylphenidate was associated with marked improvement in his ability to focus, to follow conversations, and his working memory. The subjective changes were corroborated on the Montreal cognitive assessment (MOCA) which showed improvement in his scores, especially in the area of attention. Electronic searches of The Cochrane Central Register of Controlled Trials and the standard bibliographic databases PubMed, MEDLINE, EMBASE, and PsycINFO will be performed for papers which focus on ADHD in older adults. Keywords include “late life,” “elderly,” “aged,” “senior citizen,” or “geriatric” combined with the keywords “ADHD” or “attention deficit,” Original research, case reports, and reviews will be included. Results Preliminary search conducted yielded five papers. Data from the included papers will be extracted. The epidemiology of ADHD in older adults will be discussed. This will be followed by a description of diagnostic assessment and diagnostic issues specific to older adults. The impact of ADHD in older adults will be outlined, which emphasis on its difference from that in the younger population. This will be followed by treatment considerations unique to older adults. Finally, the relationship between ADHD and cognitive impairment will be explored. Conclusions ADHD is frequently underdiagnosed and undertreated in older adults. Timely and accurate diagnosis followed by treatment results in significant improvement in symptoms and functionality. This research was funded by: None

Ventral striatum supports Methylphenidate therapeutic effects on impulsive choices expressed in temporal discounting task

Methylphenidate (MPH) is a dopamine transporter (DAT) inhibitor used to treat attention-deficit/hyperactivity-disorder (ADHD). ADHD patients make impulsive choices in delay discounting tasks (DDT) and MPH reduces such impulsivity, but its therapeutic site of action remains unknown. Based on the high density of DAT in the striatum, we hypothesized that the striatum, especially the ventral striatum (VS) and caudate nucleus which both encode temporal discounting, can be preferential MPH action sites. To determine whether one of these striatal territories is predominantly involved in the effect of MPH, we trained monkeys to make choices during DDT. First, consistent with clinical observations, we found an overall reduction of impulsive choices with a low dose of MPH administered via intramuscular injections, whereas we reported sedative-like effects with a higher dose. Then, using PET-imaging, we found that the therapeutic reduction of impulsive choices was associated with selective DAT occupancy of MPH in the VS. Finally, we confirmed the selective involvement of the VS in the effect of MPH by testing the animals’ impulsivity with microinjections of the drug in distinct striatal territories. Together, these results show that the therapeutic effect of MPH on impulsive decisions is mainly restricted to its action in the VS.

Methylphenidate Treatment of Cognitive Dysfunction in Adults After Mild to Moderate Traumatic Brain Injury: Rationale, Efficacy, and Neural Mechanisms.

Positive effects of methylphenidate (MPH) on attention and cognitive processing speed have been reported in studies of patients with moderate to severe traumatic brain injury (TBI). Studies which have acquired functional brain imaging before and while using MPH have also found alteration of brain activation while performing a cognitive task; in some studies, this alteration of activation in selective brain regions was also related to improved performance on cognitive tests administered outside of the scanning environment. Enhanced cognitive performance has been reported after single doses of MPH and after daily treatment over durations of up to and exceeding 1 month. Preclinical research and both positron emission tomography and single photon emission tomography of humans have shown that MPH increases extracellular dopamine and norepinephrine; the dose effects of MPH have an inverted U-shaped function where high doses may cause insomnia, nervousness, and increased heart rate among other symptoms and impair cognitive performance, whereas too low a dose fails to improve cognitive performance. In the past 5 years, small clinical trials, and experimental pilot studies have found therapeutic effects of single and repeated low doses of MPH in patients with mild TBI who reported cognitive dysfunction. This literature also suggests that MPH may interact with concurrent cognitive interventions to enhance their effects. This focused review will critically evaluate the recent literature on MPH effects on cognitive dysfunction after mild to moderate TBI. To elucidate the neural mechanisms of MPH effects, this review will also include recent imaging research, preclinical, and experimental human studies.

Brief and extended abstinence from chronic oral methylphenidate treatment produces reversible behavioral and physiological effects.

Methylphenidate (MP) is a commonly prescribed psychostimulant to individuals with Attention Deficit Hyperactivity Disorder, and is often used illicitly among healthy individuals with intermittent breaks to coincide with breaks from school. This study examined how intermittent abstinence periods impact the physiological and behavioral effects of chronic oral MP self-administration in rats, and whether these effects persist following prolonged abstinence from the drug. Rats were treated orally with water, low-dose (LD), or high-dose (HD) MP, beginning at PND 28. This daily access continued for three consecutive weeks followed by a 1-week abstinence; after three repeats of this cycle, there was a 5-week abstinence period. Throughout the study, we examined body weight, food intake, locomotor activity, and anxiety- and depressive-like behaviors. During the treatment phase, HD MP decreased body weight, food intake, and depressive- and anxiety-like behaviors, while it increased locomotor activity. During intermittent abstinence, the effects of MP on locomotor activity were eliminated. During prolonged abstinence, most of the effects of HD MP were ameliorated to control levels, with the exception of weight loss and anxiolytic effects. These findings suggest that intermittent exposure to chronic MP causes physiological and behavioral effects that are mostly reversible following prolonged abstinence.

Neurogenesis within the hippocampus after chronic methylphenidate exposure.

Methylphenidate is a psychostimulant used to treat attention deficit hyperactivity disorder. Neurogenesis occurs throughout adulthood within the dentate gyrus of the hippocampus and can be altered by psychoactive medications; however, the impact of methylphenidate on neurogenesis is not fully understood. We investigated the effects of chronic low (1mg/kg) and high (10mg/kg) intraperitoneal doses of methylphenidate on neurogenesis in mouse hippocampus following 28 days and 56 days of treatment. Interestingly, methylphenidate, at both doses, increased neurogenesis. However, if methylphenidate treatment was not continued, the newly generated cells did not survive after 28 days. If treatment was continued, the newly generated neurons survived only in the mice receiving low-dose methylphenidate. To investigate the mechanism for this effect, we examined levels of proteins linked to cell proliferation in the hippocampus, including brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF), tropomyosin receptor kinase B (TrkB), and beta-catenin. BDNF or GDNF levels were not significantly different between groups. However, hippocampal VEGF, TrkB, and beta-catenin were significantly increased in mice receiving low-dose methylphenidate for 28 days compared to controls. Interestingly, high-dose methylphenidate significantly decreased beta-catenin after 28 days and decreased VEGF, beta-catenin, and TrkB after 56 days compared to controls. Thus, low-dose methylphenidate appears to increase cell proliferation and cell survival in the hippocampus, and these effects may be mediated by increase in VEGF, TrkB, and beta-catenin. While high dose methylphenidate may initially increase neuronal proliferation, newly generated neurons are unable to survive long-term, possibly due to decrease in VEGF, TrkB and beta-catenin.

Chronic oral methylphenidate treatment increases microglial activation in rats.

Methylphenidate (MP) is a widely prescribed psychostimulant used to treat attention deficit hyperactivity disorder. Previously, we established a drinking paradigm to deliver MP to rats at doses that result in pharmacokinetic profiles similar to treated patients. In the present study, adolescent male rats were assigned to one of three groups: control (water), low-dose MP (LD; 4/10mg/kg), and high dose MP (HD; 30/60mg/kg). Following 3months of treatment, half of the rats in each group were euthanized, and the remaining rats received only water throughout a 1-month-long abstinence phase. In vitro autoradiography using [3H] PK 11195 was performed to measure microglial activation. HD MP rats showed increased [3H] PK 11195 binding compared to control rats in several cerebral cortical areas: primary somatosensory cortex including jaw (68.6%), upper lip (80.1%), barrel field (88.9%), and trunk (78%) regions, forelimb sensorimotor area (87.3%), secondary somatosensory cortex (72.5%), motor cortices 1 (73.2%) and 2 (69.3%), insular cortex (59.9%); as well as subcortical regions including the thalamus (62.9%), globus pallidus (79.4%) and substantia nigra (22.7%). Additionally, HD MP rats showed greater binding compared to LD MP rats in the hippocampus (60.6%), thalamus (59.6%), substantia nigra (38.5%), and motor 2 cortex (55.3%). Following abstinence, HD MP rats showed no significant differences compared to water controls; however, LD MP rats showed increased binding in pre-limbic cortex (78.1%) and ventromedial caudate putamen (113.8%). These findings indicate that chronic MP results in widespread microglial activation immediately after treatment and following the cessation of treatment in some brain regions.

Effects of Administration of Monosodium Glutamate and Methylphenidate on the Histologic Structure of Testicular Tissue and Microscopic Indices of Spermatogenesis in Adolescent Rats

Introduction: Methylphenidate (MPH) is one of the common medications used for maintaining alertness and improving attention. Monosodium glutamate (MSG) is a food additive, which acts as an enhancer of palatability. The aim of this study was to evaluate the various effects of these compounds on the reproductive system during adolescence. Materials and Methods: Methylphenidate (5 and 10 mg/kg) and monosodium glutamate (6 and 60 mg/kg) were administrated to adolescent rats. After 60 days, the pituitary-testicular axis hormones were assayed and testicular histomorphometric studies were performed. Findings: The coadministration of MPH (5 mg/kg) and MSG (60 mg/kg) led to elevation in serum FSH levels (P less-than 0.05). The highest blood level of luteinizing hormone was observed following high doses of MPH and MSG separately or in combination form. The effect of MPH and MSG on serum testosterone level was observed dose dependently and contradictorily (P greater-than 0.05). The administration of MSG led to a reduction in the population of Sertoli cells, spermatogonia, and spermatocyte. Coadministration of MPH and MSG also reduced this population. Morphometric studies revealed decrement of tubular diameter and germinal epithelium height (P less-than 0.05), especially with low doses of MPH and high doses of MSG. The changes in spermatogenic indices were similar to morphometric results. Tubular atrophy, interstitial edema, and depopulation of spermatogenic cells were observed in MPH and MSG treated groups. Coadministration of these compounds increased spermatids with pyknotic nucleus. Conclusion: It has been concluded that the coadministration of MPH and MSG through the induction of some hormonal and structural alterations could induce some changes in the normal structure and function of the reproductive system.

Weekday-only chronic oral methylphenidate self-administration in male rats: Reversibility of the behavioral and physiological effects

Methylphenidate (MP) is a commonly prescribed psychostimulant for Attention Deficit Hyperactivity Disorder (ADHD). We recently reported behavioral and developmental effects of chronic MP use in healthy rats. The current study investigated how interrupting chronic MP treatment with weekend abstinence altered the behavioral and physiological consequences of chronic MP treatment, and if prolonged abstinence would reverse the observed effects. Male Sprague Dawley rats were assigned to one of three treatment groups: water (W); low dose (LD) MP; and high dose (HD) MP. For 13 weeks, rats had access to drink from a bottle containing 4 mg/kg MP (LD), 30 mg/kg MP (HD) or water (W) for 1 h, and 10 mg/kg MP (LD), 60 mg/kg MP (HD) or water (W) for the next 7 h, each week day. During weekends, all animals received only water as well as throughout the 5-week-long abstinence phase, which immediately followed the treatment phase. Throughout the treatment phase, regardless of weekend abstinence, chronic MP resulted in significant decreased food and fluid intake and body weight. Also, HD MP exposure resulted in the following behavioral effects: increased open field and circadian locomotor activity; increased latency to immobility and decreased time spent immobile in the forced swim test; increased center activity in the open field and percent of time spent in an open arm of the elevated-plus-maze; and increased social affiliation and memory in the Crawley’s three chamber sociability test. During the prolonged (5-week) abstinence phase, all these effects were reversed while HD treated rats increased their fluid intake. These results indicated that intermittent brief abstinence periods (weekend’s off-treatment) produced the same behavioral and developmental effects as those previously reported with chronic (7 days/week) MP treatment, but were reversible following a prolonged abstinence period (5 weeks).

Recovery from behavior and developmental effects of chronic oral methylphenidate following an abstinence period

Chronic oral methylphenidate (MP) exposure in rats is associated with numerous developmental and behavioral consequences. The present study investigated the persistence of the effects of chronic oral MP exposure after abstinence from MP use. Male and female rats were exposed to daily orally self-administered water, low dose MP (LD), or high dose (HD) MP for 13 weeks, followed by a 4-week abstinence period. Fluid, food consumption and bodyweights were monitored and animals were tested for locomotor activity, anxiety- and depressive-like symptoms, learning and memory, and social behavior during both the treatment and abstinence phases of the experiment. During treatment, MP attenuated bodyweight regardless of sex, but increased food and fluid consumption in females and males by 20.7% and 30.1%, respectively. MP also increased locomotor activity in both males and females observed as increased distance travelled in an open field. (59.1% and 95.9%, respectively) and increased locomotor activity in the home cage over a 24-hour circadian cycle (45.5% and 63.0%). Additionally, MP exerted an anxiolytic effect observed as increased time spent in the open arms of an elevated plus maze (31.1% in HD males, 59.2% in HD females), and an increased latency to immobility in a forced swim test (330% in HD males, 418% in HD females). The effects of MP (bodyweight, consumption, locomotion, anxiolytic, and anti-depressive) were, almost without exception, eliminated during the abstinence period. MP had no impact on learning and memory performance as measured by a T-maze, or social behavior during treatment. These findings suggest that the behavioral consequences of chronic oral MP treatment in our preclinical model are reversible in rats following an abstinence period from use of the drug.

Effect of long‐term methylphenidate exposure on neurogenesis in the hippocampus

Attention Deficit Hyperactivity Disorder (ADHD) is a brain disorder marked by a pattern of inattention and hyperactivity that disrupts everyday functions. This disorder is commonly treated with the drug methylphenidate (MPH), which inhibits reuptake of the neurotransmitters norepinephrine and dopamine, thereby increasing the levels of these catecholamines in the synaptic cleft. In addition to its therapeutic use, MPH is commonly abused by students to increase focus and wakefulness while studying for exams. In order to better understand the long‐term effects of MPH and its pharmacologic activities, we examined the impact of 4 weeks of MPH treatment on neurogenesis in the hippocampus. Interestingly, both low (1 mg/kg) and high (10 mg/kg) doses of MPH delivered twice daily, increased the rate of neurogenesis after 4 weeks. Neurogenesis was measured using 5′‐ethinyldeoxyuridine (EdU), and mice were subjected to a 2 day methylphenidate‐free washout, injected with EdU, then brains were collected 24 hours later. Additionally, we examined the survival of the new cells 4 weeks after EdU injection; here, half of the mice received injections (saline, 1 mg/kg, and 10 mg/kg MPH) for an additional 4 weeks and half were maintained in standard housing with no injections. Mice were sacrificed via transcardial perfusion with 4% paraformaldehyde, and newly generated cells were stained for EdU using Click‐IT chemistry and were double‐labeled using immunohistochemistry for the neuronal marker, NeuN. Cell counts were performed and ratios of EdU+/NeuN+ cells were compared. Although both 1 mg/kg and 10 mg/kg MPH increased the ratio of EdU+/NeuN+ cells, the EdU+/NeuN+ ratios were no different from control (saline) if drug was not continued. Interestingly, if 1 mg/kg MPH was continued for an additional 4 weeks, survival of newly generated cells was enhanced; however, this was not the case for the high dose (10 mg/kg) of MPH. In an effort to investigate the mechanism for MPH‐induced changes in hippocampal neurogenesis, we investigated the levels of several proteins linked to cell growth and survival in the hippocampus, including brain derived neurotrophic factor (BDNF), glial cell line derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF), tropomyosin receptor kinase B (TrkB, the receptor for BDNF), and beta‐catenin. For these studies, mice were divided into 6 cohorts: 2 groups receiving 10 mg/kg of MPH for 4 or 8 weeks, 2 groups receiving 1mg/kg for 4 or 8 weeks, and 2 control groups injected with saline for 4 or 8 weeks. All 6 groups were injected twice a day, 5 days a week. After either 4 weeks or 8 weeks, mice were decapitated, brains dissected, and tissues were flash‐frozen in liquid nitrogen. Then, levels of BDNF or GDNF were examined using enzyme‐linked immunosorbent assays (ELISAs), and VEGF, TrkB, and beta‐catenin expression was investigated using simple western. Interestingly, 1 mg/kg MPH appears to increase VEGF, TrkB, and beta catenin after 4 weeks. In the animals treated with 10 mg/kg MPH, despite the observed increases in neurogenesis after 4 weeks of treatment, beta catenin levels were decreased compared to control at 4 weeks, and VEGF, TrkB, and beta catenin levels were decreased at 8 weeks. In conclusion, long‐term exposure to MPH increases neurogenesis rate in the hippocampus; this effect with low doses of MPH may be related to the increased expression of VEGF, TrkB, and beta catenin.Support or Funding InformationThis research was supported by the ETSU Research Development Committee and the Department of Pharmaceutical Sciences.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Methylphenidate ameliorates hypoxia-induced mitochondrial damage in human neuroblastoma SH-SY5Y cells through inhibition of oxidative stress

Aims: Methylphenidate (MPH) is a dopamine-reuptake inhibitor approved for the treatment of attention-deficit/hyperactivity disorder (ADHD). Nonetheless, the cellular and molecular mechanisms of MPH are still unknown. We attempt to determine whether MPH protect neuron cells against oxidative stress by using human neuroblastoma SH-SY5Y cells.Main methods: The SH-SY5Y cells were cultured in normoxic and hypoxic conditions in the presence of different doses of MPH. Then, reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and adenosine triphosphate (ATP) production were quantitatively measured by using flow cytometry or spectrophotometry. The mitochondrial ultrastructure of the cells was observed by electron microscope, and the function of mitochondrial was evaluated by measuring mitochondrial membrane potential (MMP) using flow cytometry. The levels of SOD and heme oxygenase-1 (HO-1) proteins were detected by Western blot.Key findings: We found that low doses of MPH treatment (50–500 ng/mL) led to decreased ROS and MDA production (P<0.05), increased GSH and SOD as well as ATP concentration (P<0.05) in hypoxic SH-SY5Y cells. Additionally, low doses of MPH significantly inhibited mitochondrial swelling and decreased the percentage of JC-1 monomer positive cells. However, we did not observe the same effects of MPH in normoxia.Significance: Our results show that low doses of MPH play protective roles in maintaining mitochondrial homeostasis in response to hypoxia-induced oxidative stress. Our findings may provide novel insight into the mechanisms of MPH in the treatment of ADHD, and shed light on the disease mechanisms of ADHD.