Locomotion In Rats Research Articles

The α2,3-selective potentiator of GABAA receptors, KRM-II-81, reduces nociceptive-associated behaviors induced by formalin and spinal nerve ligation in rats

Clinical evidence indicates that positive allosteric modulators (PAMs) of GABAA receptors have analgesic benefit in addition to efficacy in anxiety disorders. However, the utility of GABAA receptor PAMs as analgesics is compromised by the central nervous system side effects of non-selective potentiators. A selective potentiator of GABAA receptors associated with α2/3 subunits, KRM-II-81(5-(8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepin-3-yl)oxazole), has demonstrated anxiolytic, anticonvulsant, and antinociceptive effects in rodents with reduced motoric side effects. The present study evaluated the potential of KRM-II-81 as a novel analgesic. Oral administration of KRM-II-81 attenuated formalin-induced flinching; in contrast, diazepam was not active. KRM-II-81 attenuated nociceptive-associated behaviors engendered by chronic spinal nerve ligation (L5/L6). Diazepam decreased locomotion of rats at the dose tested in the formalin assay (10 mg/kg) whereas KRM-II-81 produced small decreases that were not dose-dependent (10–100 mg/kg). Plasma and brain levels of KRM-II-81 were used to demonstrate selectivity for α2/3- over α1-associated GABAA receptors and to define the degree of engagement of these receptors. Plasma and brain concentrations of KRM-II-81 were positively-associated with analgesic efficacy. GABA currents from isolated rat dorsal-root ganglion cultures were potentiated by KRM-II-81 with an ED50 of 32 nM. Measures of respiratory depression were reduced by alprazolam whereas KRM-II-81 was either inactive or produced effects with lower potency and efficacy. These findings add to the growing body of data supporting the idea that α2/3-selective GABAA receptor PAMs will have efficacy and tolerability as pain medications including those for neuropathic pain. Given their predicted anxiolytic effects, α2/3-selective GABAA receptor PAMs offer an additional inroad into the management of pain.

Влияние кратковременного и длительного неконтролируемого стресса на животных доминантного и субординантного социального статуса с различным типом стрессорной реакции

The aim of this study was to explore the effects of the short-term and subchronic uncontrolled stress on the behavior of animals with different of coping styles and social status. The short-term stress (forced 5-minute swimming) inhibits locomotion in subordinate rats with passive coping style, while dominants with active coping style exhibit only a slight stress reaction (grooming). Under subchronic uncontrolled stress (4-hour immobilization in confined cases for 5 days), active dominants, but not passive subordinate rats, develop the signs of a depression-like state, such as decreased body weight, increased anhedonia and anxiety, increased locomotory and research activity, and increased pain threshold, on the 5-th day of exposure, compared to the background. The subordinate rats with passive coping style show the stress reaction marked by the decreased locomotory and research activity and increased anxiety on the 5-th day of exposure. Thus, short-term and subchronic uncontrolled stress have different effects on animals with opposite social status and coping styles. These data can be useful for individual selection of appropriate antidepressants based on psychophysiological characteristics.

Кинематика локомоторных движений крыс в течение 7-дневного вывешивания

The aim of the study was to monitor the adaptive changes dynamics of locomotor control during hindlimb suspension (HS). We performed the kinematic analysis of the rat locomotor movements before, during and after 7-days HS according to the Morey-Holton. We observed the ankle and knee hyperextension in the rats’ treadmill locomotion after the 7-days HS. Despite the lack of weight-bearing position of the hindquarter, the air-stepping was present during HS. It was found the adaptive changes of the kinematic characteristic of locomotor movements during HS, namely progressive increase of ankle and knee extension, however contrary to hip flexion. These corresponded to the constrained position of hind limbs during passive suspension with the ankle, knee hyperextension, and hip hyperflexion. The data obtained indicate that the specific gait adjustments, related to the pattern formation neuronal network of the central pattern generator, is possibly caused by the progressive reorganization of the proprioceptive feedback in condition of constrained body posture and hindlimb joints configuration during HS.

Antidepressant and anxiolytic efficacy of single, chronic and concomitant use of vortioxetine, dapoxetine and fluoxetine in prenatally stressed rats

Depression is a highly prevalent social disease. Despite significant medical progress, therapeutic solutions for optimising treatment of this disease are still being sought. The aim of this study was to assess, using the forced swimming test, locomotor activity test and two compartment exploratory test, for a reduction in immobility time (a measure of anti-depressant efficacy), locomotor activity and anxiolytic effectiveness after single, repeated, and combined administration of vortioxetine (2.5 mg/kg - a multimodal SMS), dapoxetine (3.0 mg/kg - an SSRI used in premature ejaculation disorders) and fluoxetine (5.0 mg/kg - an SSRI) in non-stressed and prenatally stressed rats. It was found that vortioxetine, fluoxetine and dapoxetine reduced immobility time and rat locomotor activity which suggests anti-depressant efficacy of these drugs both in monotherapy and in combined administration. The results also confirmed an anxiolytic effect of the study drugs in mono and combined therapy. Analysis of the pathomechanism of depression and the mechanisms of action of the individual drugs tested resulted in a prediction that combined administration of these drugs may be effective in the treatment of depressive disorders, although possible interactions between the drugs used must be assessed for. Considering the fact that dapoxetine is not currently used in depression treatment and vortioxetine is a relatively new drug, further research in this direction is vital, including within animal models.

Chronic Consumption of Fructose Induces Behavioral Alterations by Increasing Orexin and Dopamine Levels in the Rat Brain.

It has been widely described that chronic intake of fructose causes metabolic alterations which can be associated with brain function impairment. In this study, we evaluated the effects of fructose intake on the sleep–wake cycle, locomotion, and neurochemical parameters in Wistar rats. The experimental group was fed with 10% fructose in drinking water for five weeks. After treatment, metabolic indicators were quantified in blood. Electroencephalographic recordings were used to evaluate the sleep architecture and the spectral power of frequency bands. Likewise, the locomotor activity and the concentrations of orexin A and monoamines were estimated. Our results show that fructose diet significantly increased the blood levels of glucose, cholesterol, and triglycerides. Fructose modified the sleep–wake cycle of rats, increasing the waking duration and conversely decreasing the non-rapid eye movement sleep. Furthermore, these effects were accompanied by increases of the spectral power at different frequency bands. Chronic consumption of fructose caused a slight increase in the locomotor activity as well as an increase of orexin A and dopamine levels in the hypothalamus and brainstem. Specifically, immunoreactivity for orexin A was increased in the ventral tegmental area after the intake of fructose. Our study suggests that fructose induces metabolic changes and stimulates the activity of orexinergic and dopaminergic neurons, which may be responsible for alterations of the sleep–wake cycle.

Modeling hind-limb kinematics using a bio-inspired algorithm with a local search

BackgroundLaboratory rats play a critical role in research because they provide a biological model that can be used for evaluating the affectation of diseases and injuries, and for the evaluation of the effectiveness of new drugs and treatments. The analysis of locomotion in laboratory rats facilitates the understanding of motor defects in many diseases, as well as the damage and recovery after peripheral and central nervous system injuries. However, locomotion analysis of rats remains a great challenge due to the necessity of labor intensive manual annotations of video data required to obtain quantitative measurements of the kinematics of the rodent extremities. In this work, we present a method that is based on the use of a bio-inspired algorithm that fits a kinematic model of the hind limbs of rats to binary images corresponding to the segmented marker of images corresponding to the rat’s gait. The bio-inspired algorithm combines a genetic algorithm for a group of the optimization variables with a local search for a second group of the optimization variables.ResultsOur results indicate the feasibility of employing the proposed approach for the automatic annotation and analysis of the locomotion patterns of the posterior extremities of laboratory rats.ConclusionsThe adjustment of the hind limb kinematic model to markers of the video frames corresponding to rat’s gait sequences could then be used to analyze the motion patterns during the steps, which, in turn, can be useful for performing quantitative evaluations of the effect of lesions and treatments on rats models.

PO-134 Optogenetics Active SNc DA Neurons Improve Locomotor Activity on Exercise-Induced fatigue Rats

Objective After optogenetics activing SNc DANs, locomotor activity ability of exercise-induced fatigue rats were recorded to research the role of nigra-striatum DA system in central mechanism of motor control.
 Methods Used male SD rats (220~240g), randomly divided into 6 groups: sham control group (SCG), optogenetics control group (OCG), fatigue group (FG), sham fatigue group (SFG) and optogenetics fatigue group (OFG). Virus ware injected in the right SNc at coordinates (AP:-5.30 mm, R: 2.00 mm, H-8.00 mm). The SCG/SFG injected 1 μ l saline, OCG/OFG injected 1 μl mixed virus(ChR2 with TH Cre,1:1), the fiber implantation site was deeper than the virus injection about 1 mm. Three weeks after surgery, rats attend 7D exhaustive treadmill exercise. After fatigue running, OCG/OFG/SCG/SFG were in the open field. We used two different light delivery schedules: 10 ms pulses at 20 Hz (10s) and 10 ms pulses at 3 Hz (10s). Sampling time were quiet state, 1D exhaustion, 7D exhaustion and recovery 24h. Animals were euthanized after completion of the behavioral tests. Brains were sectioned coronally in 50-μm slices, images were taken using a fluorescence microscope and determined the anatomical location of the optical fiber.
 Results (1) OCG/OFG obtain expression of ChR2 in DANs, this was not observed in SCG/SFG; Activation of OCG DANs with 20Hz increased the normalized mean global activity (laser on/laser off), and a significant increment in normalized mean global activity (laser on/laser off) when DANs were activated with 3Hz/20Hz in OFG (p<0.05), showing successful transfection of OCG/OFG. (2) Stimulation at 20 Hz was sufficient to improve global activity, the effects of 3 Hz did not significant, showing 20Hz stimulation possibility be related to motor regulation. (3)The global activity and total distance of rats after 7D exhaustion ware significantly lower than of quiet state (p<0.05), the difference from the quiet state and after 24h recovery is not significant, indicating that the decline in locomotor ability caused by exercise induced-fatigue is reversible. (4) The 20 Hz stimulation significantly improved the global activity of 1D and 7D exhausted rats (p<0.05), indicating that 20 Hz stimulation can effectively improve the rats locomotor activity with exercise-induced fatigue compared with 3 Hz stimulation.
 Conclusions (1) ChR2 virus transfection can effectively active the nigra-striatum DA system, causing changes in motor performance and increasing the locomotor ability of rats; (2) The locomotor ability of rats with exercise-induced fatigue to decrease. The total distance and global activity decreased significantly with exercise-induced fatigue; (3) Photoactivation of SNc DANs can improve the locomotor activity of rats with exercise-induced fatigue. From the perspective of stimulating effect, 20Hz is the most obvious activation reference point (NSFC: 31401018, SKXJX: 2014014, Corresponding houlj@bnu.edu.cn).

The mineralocorticoid receptor antagonist spironolactone reduces alcohol self-administration in female and male rats

Cortisol/corticosterone and the hypothalamic-pituitary-adrenal (HPA) axis serve an important role in modulating alcohol drinking behaviors. To date most alcohol research has focused on the functional involvement of corticosterone and the glucocorticoid receptor (GR), the primary receptor for corticosterone. Recent studies have indicated that the related mineralocorticoid receptor (MR), which binds both corticosterone and aldosterone, may also play a role in alcohol drinking. Therefore, the purpose of the present study was to test the functional role of MR signaling in alcohol self-administration via pharmacological antagonism of the MR with spironolactone. Male and female Long-Evans rats were trained to self-administer a sweetened alcohol solution (15% (v/v) alcohol +2% (w/v) sucrose). The effects of spironolactone (0, 10, 25, 50 mg/kg; IP) were tested on alcohol self-administration and under “probe extinction” conditions to measure the persistence of responding in the absence of the alcohol reinforcer. Parallel experiments in sucrose self-administration trained rats were used to confirm the specificity of spironolactone effects to an alcohol reinforcer. In female rats spironolactone (50 mg/kg) reduced alcohol self-administration and persistence of alcohol responding. In male rats spironolactone (25 and 50 mg/kg) reduced alcohol self-administration, but not persistence of alcohol responding. Spironolactone reduced sucrose intake in female rats only, and locomotion in male and female rats during sucrose self-administration. There was no effect of spironolactone on persistence of sucrose responding. These studies add to growing evidence that the MR is involved in alcohol drinking, while underscoring the importance of studying both male and female animals.

Discovery of a Potent, Selective, and Brain-Penetrant Small Molecule that Activates the Orphan Receptor GPR88 and Reduces Alcohol Intake.

The orphan G-protein-coupled receptor GPR88 is highly expressed in the striatum. Studies using GPR88 knockout mice have suggested that the receptor is implicated in alcohol seeking and drinking behaviors. To date, the biological effects of GPR88 activation are still unknown due to the lack of a potent and selective agonist appropriate for in vivo investigation. In this study, we report the discovery of the first potent, selective, and brain-penetrant GPR88 agonist RTI-13951-33 (6). RTI-13951-33 exhibited an EC50 of 25 nM in an in vitro cAMP functional assay and had no significant off-target activity at 38 GPCRs, ion channels, and neurotransmitter transporters that were tested. RTI-13951-33 displayed enhanced aqueous solubility compared to (1 R,2 R)-2-PCCA (2) and had favorable pharmacokinetic properties for behavioral assessment. Finally, RTI-13951-33 significantly reduced alcohol self-administration and alcohol intake in a dose-dependent manner without effects on locomotion and sucrose self-administration in rats when administered intraperitoneally.

Thiamine tetrahydrofurfuryl disulfide promotes voluntary activity through dopaminergic activation in the medial prefrontal cortex

A physically active lifestyle is associated with better health in body and mind, and it is urgent that supporting agents for such lifestyles be developed. In rodents, voluntary locomotor activity as an active physical behavior may be mediated by dopaminergic neurons (DNs). Thiamine phosphate esters can stimulate DNs, and we thus hypothesized that thiamine tetrahydrofurfuryl disulfide (TTFD), a thiamine derivative, promotes locomotor activity via DNs in rats. Acute i.p. administration of TTFD enhanced rat locomotor activity in a normal cage. In vivo microdialysis revealed that TTFD-enhanced locomotor activity was synchronized with dopamine release in the medial prefrontal cortex (mPFC). Antagonism of the dopamine D1 receptor, but not D2 receptor, in the mPFC fully suppressed TTFD-enhanced locomotor activity. Finally, we found a TTFD dose-dependent increase in voluntary wheel running. Our findings demonstrate that DNs in the mPFC mediates TTFD-enhanced locomotor activity, suggesting the potential of TTFD to induce active physical behavior.

Is the 3,4-methylendioxypyrovalerone/mephedrone combination responsible for enhanced stimulant effects? A rat study with investigation of the effect/concentration relationships.

The use of synthetic cathinones as recreational drugs frequently sold in combination has been increasing exponentially. However, the consequences of combining cathinones on the resulting stimulant effects and the pharmacokinetics have been poorly investigated. To study 3,4-methylenedioxypyrovalerone (MDPV; 3mg/kg) and mephedrone (4-MMC; 30mg/kg)-induced effects on rat locomotor activity and pharmacokinetics, administered alone or in combination by the intragastric route. The pharmacokinetic parameters were determined using non-compartmental analysis and the relationships between the locomotor activity and drug concentrations using sigmoidal Emax modeling. Locomotor activity significantly increased during the first hour post-administration with the MDPV/4-MMC combination in comparison to MDPV (p < 0.001) and 4-MMC (p < 0.01) alone. The pharmacokinetic profile of MDPV, but not 4-MMC, was significantly modified with the combination resulting in decreases in Cmax (16.4 ± 5.5 versus 62.2 ± 14.2μg/L, p < 0.05) and AUC0 → ∞ (708 ± 91 versus 3316 ± 682μg/L/min, p < 0.01) and increases in V/F (582.6 ± 136.8 versus 115.9 ± 42.7L/kg, p < 0.05) and Cl/F (4.6 ± 0.7 versus 1.2 ± 0.4L/kg/min, p < 0.01) in comparison to MDPV alone. The sigmoidal Emax model fitted the observed data well; MDPV being markedly more potent than 4-MMC (EC50, 0.043 versus 0.7μmol/L). The enhancing factor representing the MDPV contribution to the alteration in the relationships between locomotor activity and 4-MMC concentrations was 0.3. An MDPV/4-MMC combination results in enhanced stimulant effects in the rat, despite significant reduction in MDPV bioavailability. Enhanced effects could be explained by increased MDPV distribution and/or possible complementation at the brain dopaminergic targets. However, the exact consequences of the MDPV/4-MMC combination in humans remain to be clarified.

Spatiotemporal neuromodulation of the spinal cord in combination with a gravity-assist training to improve locomotor recovery in humans with spinal cord injury

Over the past decade, we have developed spatiotemporal neuromodulation therapies of spinal circuits and gravity-assist training procedures in pre-clinical model of spinal cord injury (SCI) which allowed to restore supraspinal control of locomotion in rats with a SCI leading to complete and permanent paralysis. So far, human studies on epidural electrical stimulation (EES) were mainly limited to continuous neuromodulation, which has demonstrated several limitations to promote the recovery of functional movements such as walking. In this study, we aimed to assess the feasibility and the efficacy of a neuroprosthetic rehabilitation program that combines spatiotemporal EES and gravity-assist training to enhance the recovery of voluntary motor control and functional autonomy. Individuals with a chronic incomplete SCI were surgically implanted with a spinal cord electrostimulation system with 16 independent electrodes positioned over the lumbar spinal cord. The stimulator was equipped with real-time triggering capacities based on movement feedback. They then underwent 20 weeks of rehabilitation, four sessions per week, with a gravity-assist that provided a tailored, multidirectional assistance of trunk movements during gait training. Multifaceted evaluations of clinical scores, gait analysis, sensorimotor functions, urodynamics, electrophysiology, and imaging were performed before and throughout the rehabilitation program. A total of 4 chronic SCI patients have been included to date, with deficits ranging from AIS-B to AIS-D. The participants who completed the study have demonstrated various types of improvements in term of muscle force, gait autonomy and quality as well as daily-life-related activities. These positive results have been observed both immediately when the EES therapy was applied and were reinforced after the long-term training. Electrophysiological and neuro-imaging analysis contributed to explaining the mechanisms underlying the long-term improvements. Preliminary data provides encouraging results on the ability of this therapeutic intervention to improve the recovery of motor functions and other important bodily functions after a chronic SCI.

Selective and non-selective OT receptor agonists induce different locomotor behaviors in male rats via central OT receptors and peripheral V1a receptors

Oxytocin (OT) continues to inspire much research due to its diverse physiological effects. While the best-understood actions of OT are uterine contraction and milk ejection, OT is also implicated in maternal and bonding behaviors, and potentially in CNS disorders such as autism, schizophrenia, and pain. The dissection of the mechanism of action of OT is complicated by the fact that this peptide activates not only its cognate receptor but also vasopressin type 1a (V1a) receptors. In this study, we evaluated OT and a selective OT receptor (OTR) agonist, FE 204409, in an automated assay that measures rat locomotor activity. The results showed: 1) Subcutaneous (sc) administration of OT decreased locomotor behavior (distance traveled, stereotypy, and rearing). This effect was reversed by a V1a receptor (V1aR) antagonist ([Pmp1,Tyr(ME)2]AVP, sc), suggesting that OT acts through peripheral V1aR to inhibit locomotor activity. 2) A selective OTR agonist (FE 204409, sc) increased stereotypy. This effect was reversed by an OTR antagonist dosed icv, suggesting a central OTR site of action. Our findings identify distinct behavioral effects for OT and the selective agonist FE 204409, adding to the growing body of evidence that the V1aR mediates many effects attributed to OT and that peptides administered systemically at supra-physiological doses may activate receptors in the brain. Our studies further emphasize the importance of utilizing selective agonists and antagonists to assess therapeutic indications.

Early movement restriction leads to enduring disorders in muscle and locomotion

Motor control and body representation in the central nervous system (CNS) as well as musculoskeletal architecture and physiology are shaped during development by sensorimotor experience and feedback, but the emergence of locomotor disorders during maturation and their persistence over time remain a matter of debate in the absence of brain damage. By using transient immobilization of the hind limbs, we investigated the enduring impact of postnatal sensorimotor restriction (SMR) on gait and posture on treadmill, age-related changes in locomotion, musculoskeletal histopathology and Hoffmann reflex in adult rats without brain damage. SMR degrades most gait parameters and induces overextended knees and ankles, leading to digitigrade locomotion that resembles equinus. Based on variations in gait parameters, SMR appears to alter age-dependent plasticity of treadmill locomotion. SMR also leads to small but significantly decreased tibial bone length, chondromalacia, degenerative changes in the knee joint, gastrocnemius myofiber atrophy and muscle hyperreflexia, suggestive of spasticity. We showed that reduced and atypical patterns of motor outputs, and somatosensory inputs and feedback to the immature CNS, even in the absence of perinatal brain damage, play a pivotal role in the emergence of movement disorders and musculoskeletal pathologies, and in their persistence over time. Understanding how atypical sensorimotor development likely contributes to these degradations may guide effective rehabilitation treatments in children with either acquired (ie, with brain damage) or developmental (ie, without brain injury) motor disabilities.

The caffeine effects on rotenone‐induced Parkinson's disease model in vitro and in vivo

Introduction and hypothesisThe degeneration and lost on dopaminergic neurons in midbrain may cause Parkinson's disease, and it is one of the most common neurodegenerative disease in human. Rotenone is a natural lipophilic toxic compound that is easy to cross the blood‐brain barrier, and widely used as insecticide and pesticide. Rotenone may impair mitochondrial oxidative phosphorylation and lead to dopaminergic neuron loss. In this study we investigated the protective effects of caffeine on rotenone‐induced Parkinson's disease models in vitro and in vivo.MethodsIn vitro, the dopaminergic cell line, SH‐SY5Y cells, is pretreated with caffeine (0~100 mM) for 30 mins and followed by treatment with rotenone (0~10 mM) for 1 hr~24 hr respectively. The cell survival rate, proliferation and morphology were analysis by flow cytometry, ELISA, Cell Counting Kit‐8(CCK‐8) and histology studies. Cell apoptosis/necrosis were analyzed by Annexin‐V/PI staining using flow cytometry. In vivo, the SD rats pretreated with caffeine (10 mg/kg daily, P.O.) or saline and followed treated with rotenone (1 mg/kg daily for 1 week, S.C.). The expressions of apoptosis and autophagy related proteins were analyzed by western blotting. The locomotion of rats were carried out by open field tests.ResultsCaffeine treatments (0–100 mM) had rarely toxic effect on SH‐SY5Y cell lines but could promote autophagy. The SH‐SY5Y cells treated with 1 nM rotenone for 8 hr may decrease the mitochondrial activity of around 60%. Pretreated with caffeine (&gt;2 mM) for 30 min and followed treated with 10 nM rotenone for 8 hr could significantly increase total cell numbers and decrease the cell apoptotic ratio, but no effect on the necrosis ratio and did not restore the mitochondrial activity on rotenone‐induced dopaminergic cell toxicity. The locomotion of SD rats that pretreated with caffeine was better than the saline control in rotenone‐induced Parkinson's disease model. After exposure to rotenone, the situation of recovery by bradykinesia in daily caffeine‐treated group is more obviously than saline control.ConclusionsIn rotenone‐induced Parkinson's disease model, caffeine could facilitate autophagy, increase cell viability and animal locomotion. Our results indicated that caffeine has the potential protective effects on rotenone‐induced Parkinson's disease model.Support or Funding InformationKMU‐TP105E37This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Hyperlocomotion induced by inhalation of nicotine and a low dose of Δ9‐Tetrahydrocannabinol in female rats

BackgroundsGrowing availability of e‐cigarette devices permits users to prepare their own cocktail of drugs for inhalation, including polysubstance inhalation. Some individuals use nicotine and (−)‐Δ9‐tetrahydrocannabinol (THC) in combination by smoking tobacco and cannabis together or in sequence; this practice may extend to electronic cigarette users. THC exerts biphasic effects on locomotion in rats, with high doses (e.g., 5 mg kg−1, i.p.) decreasing, and lower doses (e.g., 0.03 mg kg−1, i.p.) increasing, locomotor activity. Nicotine (NIC) also increases locomotor activity in rodents. This study was designed to determine if interactive effects of THC and NIC result from vapor inhalation in rats using a novel e‐cigarette based procedure.MethodsFemale Sprague‐Dawley rats were exposed to vapor produced by the propylene glycol vehicle (PG), NIC (1 mg/mL in PG), THC (12.5 mg/ml in PG) or a combination of NIC with THC for a duration of 15 minutes. Body temperature and locomotor responses were evaluated post‐inhalation using a radiotelemetry system.ResultsLocomotor activity was increased in the rats for the first 60 min after NIC (1 mg/ml) exposure and this effect was blocked by pretreatment with mecamylamine. Activity was also increased 15 min after initiation of THC vapor compared with PG. Female rats did not show any further hyperlocomotion following exposure to the combination of NIC+THC vapor compared with either NIC or THC vapor inhalation, alone. The body temperature was decreased following the THC (12.5 mg/ml) or a combination of THC (12.5 mg/ml) +NIC (1 mg/ml) inhalation with significant effects starting 120 min post‐exposure, while NIC (1 mg/ml) inhalation did not alter the body temperature.DiscussionVapor inhalation of NIC or low dose THC stimulates locomotor activity in female rats. The co‐administration of a lower dose of THC with NIC produced no additive locomotor stimulation in female rats compared to either THC or NIC alone. The observed data provided behavioral evidence to suggest that the effect of nicotine on locomotion might not be modified by the physiological action of cannabinoids.Support or Funding InformationFunding support provided by USPHS grants AA007456, DA035482 and DA041967This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Pharmacological validation of individual animal locomotion, temperature and behavioural analysis in group-housed rats using a novel automated home cage analysis system: A comparison with the modified Irwin test

BackgroundThe ActualHCA™ system continuously monitors the activity, temperature and behavior of group-housed rats without invasive surgery. The system was validated to detect the contrasting effects of sedative and stimulant test agents (chlorpromazine, clonidine and amphetamine), and compared with the modified Irwin test (mIT) with rectal temperature measurements. MethodsSix male Han Wistar rats per group were used to assess each test agent and vehicle controls in separate ActualHCA™ recordings and mIT. The mIT was undertaken at 15, 30 mins, 1, 2, 4 and 24 h post-dose. ActualHCA™ recorded continuously for 24 h post-dose under 3 experimental conditions: dosed during light phase, dark phase, and light phase with a scheduled cage change at the time of peak effects determined by mIT. ResultsActualHCA™ detected an increase stimulated activity from the cage change at 1-2 h post-dose which was obliterated by chlorpromazine and clonidine. Amphetamine increased activity up to 4 h post-dose in all conditions. Temperature from ActualHCA™ was affected by all test agents in all conditions. The mIT showed effects on all 3 test agents up to 4 h post-dose, with maximal effects at 1-2 h post-dose. The maximal effects on temperature from ActualHCA™ differed from mIT. Delayed effects on activity were detected by ActualHCA™, but not on mIT. ConclusionsContinuous monitoring has the advantage of capturing effects over time that may be missed with manual tests using pre-determined time points. This automated behavioural system does not replace the need for conventional methods but could be implemented simultaneously to improve our understanding of behavioural pharmacology.

Dose-dependent reduction in cocaine-induced locomotion by Clozapine-N-Oxide in rats with a history of cocaine self-administration

Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) are novel tools for the dissection of circuitry mediating behavior and neural function. Designer receptors based on the muscarinic M3 and M4 subtypes were designed to be activated by clozapine-N-oxide (CNO), a ligand previously shown to be an inert metabolite of clozapine. However, recent work in rats has shown that CNO is reverse metabolized to its parent compound. Furthermore, CNO administration (5 mg/kg IP) attenuates amphetamine-induced locomotion and the evoked dopamine response that accompanies it. As these systems are routinely used to probe the neurocircuitry underlying cocaine-seeking behavior, here we sought to determine whether CNO would have similar effects on cocaine-induced locomotion in rats with a history of cocaine self-administration. In order for muscarinic-based DREADDs to be utilized for the dissection of circuitry underlying behavioral responses to cocaine, the doses of CNO administered to induce DREADD signaling must themselves have no effect on cocaine-induced behavior. Male Sprague-Dawley rats self-administered cocaine (0.35 mg/infusion) for 12 days, followed by 14–21 days of instrumental extinction training. Rats then underwent locomotor testing. CNO (0, 3, or 5 mg/kg) was injected (utilizing a within-subjects design), followed 20 min later by cocaine (10 mg/kg IP). Locomotion was monitored for the following 120 min. We found that the 5, but not the 3 mg/kg, dose of CNO reduced cocaine-induced locomotion. Thus, studies utilizing DREAADs to probe cocaine-induced behavior should consider these findings when choosing a dose of CNO and include non-DREADD CNO controls.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats

BackgroundSpinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA).MethodsOA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg− 1 day− 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker’s and behavioural experiments.ResultsIn vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test.ConclusionOn the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Motor deficits following dorsal corticospinal tract transection in rats: voluntary versus skilled locomotion readouts

Following spinal cord injury, severe deficits result from damages to ascending and descending tracts, such as the corticospinal tract (CST) which is highly relevant for the motor execution in humans. Unfortunately, no curative treatment is available and intensive efforts are deployed in animal models, such as the CST transection model, to identify interventions providing functional regeneration after spinal cord injury.The CatWalk XT is a system for multi-parameter gait analysis of voluntary locomotion. In this study, the performance of the CatWalk XT for monitoring of functional deficits associated with dorsal CST lesion in rats was compared to skilled locomotion tests. Motor deficits associated with dorsal CST transection could be reliably monitored over seven weeks based on skilled locomotion testing, i.e. Horizontal Ladder Walk and Grid Walk. The collateral lesion to the overlaying gracile and cuneate funiculi occurring during dorsal CST transection resulted in slight hyposensitivity and proprioceptive deficit, which likely contributed to the lowered performance in skilled locomotion. In contrast, parameters of voluntary locomotion were not significantly affected by dorsal CST transection. Finally, an abnormal adduction reflex was detected immediately after lesion of the CST and could be conveniently used to confirm successful CST lesion in rats of experimental groups.The functional relevance of the dorsal CST in locomotion of rats is not as prominent as compared to in humans and thus challenging the motor execution is mandatory to reliably investigate CST function. A detailed analysis of voluntary walking using the CatWalk XT is not adequate to detect deficits following dorsal CST lesion in rats.