Reserpine Treatment Research Articles

A Novel Way of Amelioration of Amyloid Beta Induced Toxicity in Caenorhabditis elegans

Background: With an incidence of 1 in 85 persons above the age of 60 years succumbing to the disease, Alzheimer's disease (AD), has been predicted to create havoc globally. In spite of enormous efforts and exhaustive research, no cure is in sight. Hence, it is critical to unravel the mechanism of AD development/protection and identification of a cure soon. Purpose: This study is aimed at investigating the mechanism of reserpine action, which alleviates the toxicity of amyloid beta (Aβ) (AD-causing peptide) in Caenorhabditis elegans [<citeref rid="ref1">1</citeref>,<citeref rid="ref2">2</citeref>]. Methods: Determination of alleviation of Aβ toxicity with reserpine manifested as reduction in progressive paralysis, in the background of GFP reporter driven by the promoter of the FMRFamide neuropeptide, FLP-11 (AD; P_flp-11::GFP) and acetylcholine contribution through aldicarb (which inhibits acetylcholine esterase) treatment. Results: The most significant protection against Aβ toxicity was obtained in the background of P_flp-11::GFP. This protection had 2 components. The promoter of FLP-11 with the reporter GFP, P_flp-11::GFP, per se gave significant protection. Further reserpine treatment provided additional alleviation. Together they could almost eliminate Aβ toxicity. These 2 components of Aβ toxicity alleviation are dependent on acetylcholine levels, as an increase in acetylcholine by aldicarb treatment reduces the protective effect. Conclusion: A unique way to alleviate Aβ toxicity is reserpine treatment in combination with P_flp-11::GFP. Reserpine should be evaluated as a potential drug in a pilot study in AD patients. Furthermore, identification of the mechanism of Pflp-11::GFP-mediated reduction in Aβ toxicity is a potential pathway to develop therapeutics for AD.

Antidepressant-like effect of hydroalcoholic extract of Valeriana prionophylla Standl. from Guatemala: Evidence for the involvement of the monoaminergic systems

Background: Previous studies carried out in our laboratories have shown that Valeriana prionophylla displays central effects in mice. The antidepressant effect of the Valeriana prionophylla was the most prominent effect. The goal of this study was to evaluate the mechanism of action of the antidepressant property of HEVp, and its effect when used chronically.Methods: Experiments were performed using the forced swimming test and the open field test. Female Swiss mice (25-30 g, 3 months) were divided into groups (N=8-10): negative control (saline), antagonist systems evaluated, HEVp and antagonist/HEVp. The treatments with NAN-190 (0.5 mg/kg, i.p.), ketanserin (5 mg/kg, i.p.), prazosin (1 mg/kg, i.p.), yohimbine (1 mg/kg, i.p.), haloperidol (0.2 mg/kg, i.p.), pimozide (0.2 mg/kg, i.p.), SCH-23390 (0.05 mg/kg, i.p.), L-arginine (750 mg/kg, i.p.), bicuculline (1 mg/kg, i.p.) and phaclofen (1 mg/kg, i.p.) were administered 30 min before HEVp. The treatments with reserpine (2 mg/kg, i.p.) and PCPA (100 mg/kg, i.p.) were administered 4 hours and 4 days before the test, respectively. Sub-chronic treatment was administered for 15 days, and the test was performed on days 1, 7 and 15 of the treatment.Results: The anti-immobility effect caused by HEVp was significantly attenuated by treatment of the reserpine, PCPA, NAN-190, ketanserin, prazosin, yohimbine, L-arginine, bicuculline and phaclofen, but was not affected by haloperidol, pimozide and SCH-23390.Conclusion: The mechanisms involved in their effects indicate that HEVp produces antidepressant effects through pathways that involve interaction with L-arginine-nitric oxide, serotonergic and GABAergic systems, as well as interaction with the ?-adrenoceptors.

Curcumin Ameliorates Reserpine-Induced Gastrointestinal Mucosal Lesions Through Inhibiting IκB-α/NF-κB Pathway and Regulating Expression of Vasoactive Intestinal Peptide and Gastrin in Rats.

The objective of our study was to investigate whether curcumin protects against reserpine-induced gastrointestinal mucosal lesions (GMLs) in rats and to explore the mechanism of curcumin's action. Sprague-Dawley rats were randomly divided into four groups: control group, reserpine-treated group, reserpine treatment group with curcumin at high dose (200 mg/kg), and reserpine treatment group with curcumin at low dose (100 mg/kg). Rats in reserpine-treated group were induced by intraperitoneally administered reserpine (0.5 mg/kg) for 28 days. TUNEL staining and hematoxylin and eosin staining were used to evaluate the apoptotic cells and morphologic changes. In addition, to explore the mechanism of curcumin in protecting GMLs, we used serum of experimental rats to assess the level of vasoactive intestinal peptide (VIP), gastrin, interleukin-6, interleukin-10, tumor necrosis factor-α and interferon-γ by ELISA and radioimmunoassay. The protein levels of NF-κB, p-IκB-α, IκB-α, Bcl-2, Bax, and cleaved-caspase-3 were examined by western blot analysis. Data were analyzed with SPSS 19.0 software package. Curcumin treatment prevented tissue damage and cell death in the reserpine-treated rats and effectively decreased inflammatory response and balanced the expression of VIP and gastrin in the reserpine-treated rats. NF-κB, p-IκB-α, Bax, and cleaved-caspase-3 were increased in the reserpine group, but the curcumin high-dose group inhibited them. Curcumin can target the IκB-α/NF-κB pathway to inhibit inflammatory response and regulate the level of VIP and gastrin in reserpine-induced GML rats.

The anti-hypertensive drug reserpine induces neuronal cell death through inhibition of autophagic flux

Reserpine is a well-known medicine for the treatment of hypertension and schizophrenia, but its administration can induce Parkinson's disease (PD)-like symptoms in humans and animals. Reserpine inhibits the vesicular transporter of monoamines and depletes the brain of monoamines such as dopamine. However, the cellular function of reserpine is not fully understood. In this report, we present one possible mechanism by which reserpine may contribute to PD-like symptoms. Reserpine treatment induced the formation of enlarged autophagosomes by inhibiting the autophagic flux and led to accumulation of p62, an autophagy adapter molecule. In particular, reserpine treatment increased the level of α-synuclein protein and led to accumulation of α-synuclein in autophagosomes. Treatment with rapamycin enhanced the effect of reserpine by further increasing the level of α-synuclein and neuronal cell death. Drosophila raised on media containing reserpine showed loss of dopaminergic neurons. Furthermore, cotreatment with reserpine and rapamycin aggravated the loss of dopaminergic neurons. Our results suggest that reserpine contributes to the loss of dopaminergic neurons by interfering with autophagic flux.

Resistance of Stenotrophomonas maltophilia to Fluoroquinolones: Prevalence in a University Hospital and Possible Mechanisms.

Objective: The purpose of this study was to investigate the clinical distribution and genotyping of Stenotrophomonas maltophilia, its resistance to antimicrobial agents, and the possible mechanisms of this drug resistance. Methods: S. maltophilia isolates were collected from clinical specimens in a university hospital in Northwestern China during the period between 2010 and 2012, and were identified to the species level with a fully automated microbiological system. Antimicrobial susceptibility testing was performed for S. maltophilia with the Kirby-Bauer disc diffusion method. The minimal inhibitory concentrations (MICs) of norfloxacin, ofloxacin, chloramphenicol, minocycline, ceftazidime, levofloxacin and ciprofloxacin against S. maltophilia were assessed using the agar dilution method, and changes in the MIC of norfloxacin, ciprofloxacin and ofloxacin were observed after the addition of reserpine, an efflux pump inhibitor. Fluoroquinolone resistance genes were detected in S. maltophilia using a polymerase chain reaction (PCR) assay, and the expression of efflux pump smeD and smeF genes was determined using a quantitative fluorescent (QF)-PCR assay. Pulsed-field gel electrophoresis (PFGE) was employed to genotype identified S. maltophilia isolates. Results: A total of 426 S. maltophilia strains were isolated from the university hospital from 2010 to 2012, consisting of 10.1% of total non-fermentative bacteria. The prevalence of norfloxacin, ciprofloxacin and ofloxacin resistance was 32.4%, 21.9% and 13.2% in the 114 S. maltophilia isolates collected from 2012, respectively. Following reserpine treatment, 19 S. maltophilia isolates positive for efflux pump were identified, and high expression of smeD and smeF genes was detected in two resistant isolates. gyrA, parC, smeD, smeE and smeF genes were detected in all 114 S. maltophilia isolates, while smqnr gene was found in 25.4% of total isolates. Glu-Lys mutation (GAA-AAA) was detected at the 151th amino acid of the gyrA gene, while Gly-Arg mutation (GGC-CGC) was found at the 37th amino acid of the parC gene. However, no significant difference was observed in the prevalence of gyrA or parC mutation between fluoroquinolone-resistant and -susceptible isolates (p> 0.05). The smqnr gene showed 92% to 99% heterogenicity among the 14 S. maltophilia clinical isolates. PFGE of 29 smqnr gene-positive S. maltophilia clinical isolates revealed 25 PFGE genotypes and 28 subgenotypes. Conclusions: Monitoring the clinical distribution and antimicrobial resistance of S. maltophilia is of great significance for the clinical therapy of bacterial infections. Reserpine is effective to inhibit the active efflux of norfloxacin, ciprofloxacin and ofloxacin on S. maltophilia and reduce MIC of fluoroquinolones against the bacteria. The expression of efflux pump smeD and smeF genes correlates with the resistance of S. maltophilia to fluoroquinolones.

The metabolism of histamine in rat hypothalamus and cortex after reserpine treatment

The effect of reserpine on histamine (HA) and tele-methylhistamine (Nτ-MHA) in hypothalamus and cortex of rats was analyzed and compared to catecholamines. IP injection of reserpine (5 mg/kg) confirmed the effectiveness of reserpine treatment on noradrenaline and dopamine levels. Our in-vitro experiment with synaptosomal/crude mitochondrial fraction from hypothalamus and cortex confirmed that while mono amine oxidase (MAO) is an efficient metabolic enzyme for catecholamines, HA is not significantly affected by its enzymatic action. HMT activity after reserpine, pargyline and L-histidine treatment showed no differences compared to the control values. However HDC was significantly increased in both hypothalamus and cortex. In this study, Ws/Ws rats with deficiency of mast cells were used to clarify aspects of HA metabolism in HAergic neurons by eliminating the contribution of mast cells.The irreversible MAO-B inhibitor Pargyline (65 mg/kg) failed to accumulate Nτ-MHA in the hypothalamus. However, when animals treated with reserpine and pargyline/reserpine were compared, the last group showed higher Nτ-MHA values (p < 0.01). Moreover, the precursor of HA, L-histidine (1 g/kg), produced an increase of HA in the hypothalamus to 166% and the cortex to 348%.In conclusion, our results suggest that the effect of reserpine on the HA pools in the brain might be different. The neuronal HA pools are more resistant to reserpine as compared to those of catecholamine. Moreover, the HAergic pool appears to be more resistant to depletion than mast cells' pool, and thus HDC/HMT activity and its localization may play a key role in the understanding of HA metabolism in brain after reserpine treatment.

Adenosine signaling in reserpine-induced depression in rats

A single, 6mg/kg intraperitoneal injection of reserpine increased floating time during forced swim testing 24h after administration in rats in five experiments. Although such behavioral depression traditionally is attributed to drug-induced depletion of brain monoamines, we examined the potential contribution of adenosine signaling, which is plausibly activated by reserpine treatment and contributes to behavioral depression in other paradigms. Whereas peripheral administration of the highly selective A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (0.5, 1.0, or 5.0mg/kg i.p.) 15min before swim testing failed to improve performance in reserpine-treated rats, swim deficits were completely reversed by 7mg/kg of the nonselective receptor antagonist caffeine. Performance deficits were also reversed by the nonselective A2 antagonist 3,7-dimethylxanthine (0, 0.5, 1.0mg/kg i.p.), and the highly selective A2A receptor antagonist (CSC: 8-(3chlorostyral)caffeine) (0.01, 0.1, or 1.0mg/kg i.p.) in a dose-dependent manner. The highly selective A2B antagonist alloxazine had no beneficial effect on swim performance at any dose under study (0.1, 1.0, and 5.0mg/kg i.p.).

Magnesium Supplementation Prevents and Reverses Experimentally Induced Movement Disturbances in Rats: Biochemical and Behavioral Parameters.

Reserpine administration results in a predictable animal model of orofacial dyskinesia (OD) that has been largely used to access movement disturbances related to extrapyramidal oxidative damage. Here, OD was acutely induced by reserpine (two doses of 0.7mg/kg subcutaneous (s.c.)), every other day for 3days), which was administered after (experiment 1) and before (experiment 2) magnesium (Mg) supplementation (40mg/kg/mL, peroral (p.o.)). In experiment 1, Mg was administered for 28days before reserpine treatment, while in experiment 2, it was initiated 24h after the last reserpine administration and was maintained for 10 consecutive days. Experiment 1 (prevention) showed that Mg supplementation was able to prevent reserpine-induced OD and catalepsy development. Mg was also able to prevent reactive species (RS) generation, thus preventing increase of protein carbonyl (PC) levels in both cortex and substantia nigra, but not in striatum. Experiment 2 (reversion) showed that Mg was able to decrease OD and catalepsy at all times assessed. In addition, Mg was able to decrease RS generation, with lower levels of PC in both cortex and striatum, but not in substantia nigra. These outcomes indicate that Mg is an important metal that should be present in the diet, since its intake is able to prevent and minimize the development of movement disorders closely related to oxidative damage in the extrapyramidal brain areas, such as OD.

(−) Epigallocatechin-3-gallate attenuates reserpine-induced orofacial dyskinesia and oxidative stress in rat striatum

Reserpine-induced orofacial dyskinesia (OD) has been used for decades as an animal model for human tardive dyskinesia (TD) because both of them have pathophysiology strongly associated with striatal oxidative stress. Green tea catechins, especially (−) epigallocatechin-3-gallate (EGCG), have potent antioxidative effects and are able to protect against various oxidative injuries. In this study, we examined the potential protective effects of EGCG on reserpine-induced behavioral and neurochemical dysfunction in rats. Reserpine treatment (1mg/kgs.c. one injection every other day, three injections total) induced significant increases (p<0.001) in the frequency of vacuous chewing movement (VCM) and tongue protrusion (TP) as well as the duration of facial twitching (FT). EGCG treatment (100mg/kgi.p. for 11days, starting 7days before the reserpine injections) was able to prevent most of the reserpine-induced OD. Also, EGCG treatment was able to reduce the reserpine-induced lipid peroxidation (LPO) production, and enhances the antioxidation power in the striatum of reserpine-treated rats. The above results indicate that EGCG has a protective role against reserpine-induced OD, probably via its powerful antioxidative properties. Thus, EGCG may possible have a clinically relevant therapeutic effect in preventing, delaying or even treating TD.

Alpha-Tocopherol Counteracts Cognitive and Motor Deficits Induced by Repeated Treatment with Reserpine

Previous studies showed that chronic administration of the monoamine depleting agent reserpine in low doses promotes progressive cognitive and motor impairments in rats, and this protocol has been used as a pharmacological progressive model of Parkinson's disease. These behavioral alterations are accompanied by increased brain oxidative stress. We aimed to verify the effects of the concomitant treatment with the antioxidant agent alpha-tocopherol on the motor and cognitive deficits induced by chronic reserpine in rats. Rats were repeatedly treated with 0.1 mg/kg reserpine with or without a concomitant treatment with 40 mg/kg alpha-tocopherol. Across the treatment, motor and cognitive performances were evaluated by the catalepsy and novel object recognition tests, respectively. As expected, reserpinetreated rats showed progressively increased duration of catalepsy together with short-term memory deficits in the object recognition test. Importantly, these detrimental outcomes due to reserpine treatment were prevented by concomitant daily administration of the antioxidant agent alpha-tocopherol. The results show a preventive role of alpha-tocopherol on behavioral alterations induced by repeated reserpine treatment. This is relevant to the investigation of possible neuroprotective interventions in Parkinson’s disease.

Effects of dopamine uptake inhibitor MRZ-9547 in animal models of Parkinson's disease.

MRZ-9547 (d-(2-(2-oxo-4(R)-phenylpyrrolidin-1-yl)-acetamide) is a drug acting at the dopamine transporter (DAT). In the present study, effects of MRZ-9547 alone and in combination with L-3,4-dihydroxyphenylalanine (L-DOPA) were investigated in rodent models predictive for efficacy in Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID). In rats pre-treated with haloperidol (0.2 mg/kg i.p.), MRZ-9547 (25-100 mg/kg i.p.) dose-dependently attenuated decrease in horizontal locomotion, activity in central zone, and rearings starting at 50 mg/kg i.p. In rats depleted of monoamines by α-methyl-p-tyrosine and reserpine treatment, MRZ-9547 attenuated hypolocomotion starting at 100 mg/kg i.p. At the doses 25-100 mg/kg i.p. the drug induced dose-dependent ipsilateral rotations in rats with unilateral 6-hydroxydopamine (6-OHDA)-induced nigrostriatal system lesions. However, MRZ-9547 enhanced contralateral rotation produced by L-DOPA given at an effective (25 mg/kg i.p.), but not at a sub-effective (6.25 mg/kg i.p.) dose. Microdialysis experiments revealed that MRZ-9547 penetrated well to the brain and did not show any pharmacokinetic interaction with L-DOPA. In unilaterally 6-OHDA-lesioned rats having developed abnormal involuntary movements (AIMs, a rodent correlate of LID) after chronic L-DOPA treatment, MRZ-9547 (50 mg/kg i.p.) did not significantly affect the AIMs expression. The results indicate that MRZ-9547 may by itself have antiparkinsonian activity at early stages of the disease, when some dopaminergic terminals are still intact. It may also enhance antiparkinsonian effect of L-DOPA. MRZ-9547 does not seem to influence the expression of LID in 6-OHDA-lesioned rats. The results support the use of MRZ-9547 in PD patients treated with L-DOPA.

Lack of dopaminergic inputs elongates the primary cilia of striatal neurons.

In the rodent brain, certain G protein-coupled receptors and adenylyl cyclase type 3 are known to localize to the neuronal primary cilium, a primitive sensory organelle protruding singly from almost all neurons. A recent chemical screening study demonstrated that many compounds targeting dopamine receptors regulate the assembly of Chlamydomonas reinhardtii flagella, structures which are analogous to vertebrate cilia. Here we investigated the effects of dopaminergic inputs loss on the architecture of neuronal primary cilia in the rodent striatum, a brain region that receives major dopaminergic projections from the midbrain. We first analyzed the lengths of neuronal cilia in the dorsolateral striatum of hemi-parkinsonian rats with unilateral lesions of the nigrostriatal dopamine pathway. In these rats, the striatal neuronal cilia were significantly longer on the lesioned side than on the non-lesioned side. In mice, the repeated injection of reserpine, a dopamine-depleting agent, elongated neuronal cilia in the striatum. The combined administration of agonists for dopamine receptor type 2 (D2) with reserpine attenuated the elongation of striatal neuronal cilia. Repeated treatment with an antagonist of D2, but not of dopamine receptor type 1 (D1), elongated the striatal neuronal cilia. In addition, D2-null mice displayed longer neuronal cilia in the striatum compared to wild-type controls. Reserpine treatment elongated the striatal neuronal cilia in D1-null mice but not in D2-null mice. Repeated treatment with a D2 agonist suppressed the elongation of striatal neuronal cilia on the lesioned side of hemi-parkinsonian rats. These results suggest that the elongation of striatal neuronal cilia following the lack of dopaminergic inputs is attributable to the absence of dopaminergic transmission via D2 receptors. Our results provide the first evidence that the length of neuronal cilia can be modified by the lack of a neurotransmitter's input.

Prevalence and Antimicrobial Resistance of Enterococcus Species: A Hospital-Based Study in China

Objective: to investigate the prevalence and antimicrobial resistance of Enterococcus species isolated from a university hospital, and explore the mechanisms underlying the antimicrobial resistance, so as to provide clinical evidence for the inappropriate clinical use of antimicrobial agents and the control and prevention of enterococcal infections. Methods: a total of 1,157 enterococcal strains isolated from various clinical specimens from January 2010 to December 2012 in the General Hospital of Ningxia Medical University were identified to species level with a VITEK-2 COMPACT fully automated microbiological system, and the antimicrobial susceptibility of Enterococcus species was determined using the Kirby-Bauer disc diffusion method. The multiple-drug resistant enterococcal isolates were screened from the clinical isolates of Enterococcus species from the burns department. The minimal inhibitory concentration (MIC) of Enterococcus species to the three fluoroquinolones, including ciprofloxacin, gatifloxacin and levofloxacin was determined with the agar dilution method, and the changes in the MIC of Enterococcus species to the three fluoroquinolones following reserpine treatment were evaluated. The β-lactam, aminoglycoside, tetracycline, macrolide, glycopeptide resistance genes and the efflux pump emeA genes were detected in the enterococcal isolates using a polymerase chain reaction (PCR) assay. Results: the 1,157 clinical isolates of Enterococcus species included 679 E. faecium isolates (58.7%), 382 E. faecalis isolates (33%), 26 E. casseliflavus isolates (2.2%), 24 E. avium isolates (2.1%), and 46 isolates of other Enterococcus species (4%). The prevalence of antimicrobial resistance varied significantly between E. faecium and E. faecalis, and ≤1.1% of these two Enterococcus species were found to be resistant to vancomycin, teicoplanin or linezolid. In addition, the Enterococcus species isolated from different departments of the hospital exhibited various resistances to the same antimicrobial agent, while reserpine treatment reduced the resistance of Enterococcus species to ciprofloxacin, gatifloxacin and levofloxacin. The β-lactamase gene TEM, aminoglycoside-modifying-enzyme genes aac(6')-aph(2"), aph(3')-III, ant(6)-I and ant(2")-I, tetracycline resistance gene tetM, erythromycin resistance gene ermB, vancomycin resistance gene vanA and the enterococcal multidrug resistance efflux emeA gene were detected in 77%, 62%, 26%, 13%, 36%, 31%, 66%, 5% and 55% of the 100 multiple-drug resistant enterococcal isolates. Conclusions: similar to previous findings, E. faecium and E. faecalis are predominant conditionally pathogenic bacteria that cause hospital-acquired infections that can cause urinary and respiratory system infections. Multiple and high-level antimicrobial resistance is highly prevalent in the hospital isolates of Enterococcus species. Reserpine treatment inhibits the active efflux of Enterococcus species to ciprofloxacin, gatifloxacin and levofloxacin in vitro and reduces the MIC of Enterococcus species to these three fluoroquinolones. The presence of the enterococcal multidrug resistance efflux emeA gene is associated with the resistance to antibiotics in Enterococcus species. The monitoring of the prevalence and antimicrobial resistance of Enterococcus species is of great significance to guide the control and prevention of enterococcal infections.

5-HT7 Receptors and Tryptophan Hydroxylase in Lymphocytes of Rats: Mitogen Activation, Physical Restraint or Treatment with Reserpine

Objectives: Serotonin (5-HT)₇ receptors in lymphocytes play a relevant role as modulators of T cell functions and might be modified by stress protocols. The aims of this work were to evaluate: (i) the presence of 5-HT₇ receptors in specific lymphocyte populations, (ii) the probable modifications of them by inflammatory stress with mitogen and (iii) the effects of physical and pharmacological stress. Methods: Blood lymphocytes were isolated by density gradients and differential adhesion to plastic. Concanavalin A (Con A) was systemically administered (500 μg/kg) or added to lymphocyte cultures (2.5 μg/ml, final volume 200 μl). Physical restraint was performed in Plexiglass boxes for 5 h per day for 5 days. Reserpine administration was 2.5 mg/kg for 3 days. Immunocytochemical labeling of CD4+, CD8+ and 5-HT₇ receptors, and also tryptophan hydroxylase cells was performed. mRNA of 5-HT₇ receptors was evaluated by RT-PCR. Controls were included for each protocol. Results: Con A treatment or culture exposure increased the number of lymphocytes expressing 5-HT₇ receptors or tryptophan hydroxylase, as compared to absence of the mitogen. Receptors were present in 12-16% of total rat lymphocytes, in ∼10% of CD4+ and in ∼5% of CD8+ cells from control rats. CD4+ decreased, and CD8+ and 5-HT₇ cells increased after physical restraint. Reserpine treatment elevated CD8+ and 5-HT₇ cells. Con A and physical restraint, but not reserpine treatment, significantly augmented 5-HT₇ receptor mRNA in lymphocytes. Conclusions: Rat lymphocytes, expressing tryptophan hydroxylase, could synthesize 5-HT, functioning as a direct autocrine modulator. The modifications of CD4+, CD8+ and 5-HT₇ receptors in lymphocytes by three stress protocols could have an impact on immune responses. In addition, the differential distribution of 5-HT₇ receptors indicates potential specific physiopathological roles.

The effects of Phα1β, a spider toxin, calcium channel blocker, in a mouse fibromyalgia model

This study investigated the effects of Phα1β, pregabalin and diclofenac using an animal model of fibromyalgia (FM). Repeated administration of reserpine (0.25 mg/kg sc) once daily for three consecutive days significantly decreased thermal hyperalgesia, mechanical allodynia, and dopamine and serotonin content in the brain on the 4th day. Phα1β and pregabalin treatment completely reverted the mechanical allodynia and thermal hyperalgesia induced by reserpine treatment on the 4th day, but diclofenac was ineffective. Reserpine treatment significantly increased the immobility time in the forced swim test, which is indicative of depression in the animals. Phα1β, but not pregabalin, reduced the immobility time (56%), suggesting that Phα1β may control persistent pathological pain in FM.

The analgesic effect of tramadol in animal models of neuropathic pain and fibromyalgia

(±)-Tramadol hydrochloride (tramadol) is a widely used analgesic for the treatment of cancer pain and chronic pain. Although many animal studies have shown antinociceptive effects of tramadol in both acute and chronic pain, little is known about the effect of tramadol in putative animal models of fibromyalgia. In this study, we compared the antiallodynic effects of oral administration of tramadol in two kinds of rat chronic pain models, neuropathic pain induced by partial sciatic nerve ligation (PSL) and reserpine-induced myalgia (RIM). In PSL rats, the threshold for responses induced by tactile stimulation with von Frey filaments was significantly decreased seven days after the operation, suggesting that the operation induced tactile allodynia. Orally administered tramadol showed a potent and dose-dependent antiallodynic effect on PSL-induced allodynia. In RIM rats, the threshold was significantly decreased five days after reserpine treatment. Orally administered tramadol also attenuated reserpine-induced tactile allodynia. To explore the mechanism of the antiallodynic effect of tramadol in RIM rats, we investigated the effect of the opioid antagonist naloxone on the tramadol-induced analgesic effect in these rats. The effect of tramadol was partially antagonized by naloxone, suggesting that the opioid receptor is involved at least in part in the antiallodynic effect of tramadol in RIM rats. These data indicate that orally administered tramadol produced improvement in both PSL rats and RIM rats at similar doses and provide evidence that the opioid system is partly involved in the analgesic effect of tramadol in RIM rats.

Effect of Hypericum perforatum on different models of movement disorders in rats

The effects of Hypericum perforatum, a plant with antidepressant action, were evaluated in models of abnormal movements in rats, brought about by administration of fluphenazine or reserpine. The number of vacuous chewing movements (VCMs) and locomotor activity (the number of crossings and rears in the open field test) were measured. In experiment 1, rats received a single administration of fluphenazine enanthate (25 mg/kg, intramuscular) and/or daily treatment with H. perforatum (300 mg/kg, in place of drinking water) for 7 days. Fluphenazine increased VCMs and decreased locomotor activity. H. perforatum had no effect on either the number of VCMs or the locomotor activity. In experiment 2, rats received reserpine every 2 days for 6 days (0.5 mg/kg, subcutaneous) and/or H. perforatum (300 mg/kg, in place of drinking water) daily for 16 days beginning 10 days before the first administration of reserpine. Reserpine treatment increased VCMs and decreased locomotor activity. H. perforatum had no effect on either the number of VCMs or the number of rears but did prevent the effect of reserpine on the number of crossings. In conclusion, H. perforatum failed to protect against orofacial movements induced by fluphenazine or reserpine in rats.

Evidence for a Critical Role of Catecholamines for Cardiomyocyte Lineage Commitment in Murine Embryonic Stem Cells

Catecholamine release is known to modulate cardiac output by increasing heart rate. Although much is known about catecholamine function and regulation in adults, little is known about the presence and role of catecholamines during heart development. The present study aimed therefore to evaluate the effects of different catecholamines on early heart development in an in vitro setting using embryonic stem (ES) cell-derived cardiomyocytes. Effects of catecholamine depletion induced by reserpine were examined in murine ES cells (line D3, αPIG44) during differentiation. Cardiac differentiation was assessed by immunocytochemistry, qRT-PCR, quantification of beating clusters, flow cytometry and pharmacological approaches. Proliferation was analyzed by EB cross-section measurements, while functionality of cardiomyocytes was studied by extracellular field potential (FP) measurements using microelectrode arrays (MEAs). To further differentiate between substance-specific effects of reserpine and catecholamine action via α- and β-receptors we proved the involvement of adrenergic receptors by application of unspecific α- and β-receptor antagonists. Reserpine treatment led to remarkable down-regulation of cardiac-specific genes, proteins and mesodermal marker genes. In more detail, the average ratio of ∼40% spontaneously beating control clusters was significantly reduced by 100%, 91.1% and 20.0% on days 10, 12, and 14, respectively. Flow cytometry revealed a significant reduction (by 71.6%, n = 11) of eGFP positive CMs after reserpine treatment. By contrast, reserpine did not reduce EB growth while number of neuronal cells in reserpine-treated EBs was significantly increased. MEA measurements of reserpine-treated EBs showed lower FP frequencies and weak responsiveness to adrenergic and muscarinic stimulation. Interestingly we found that developmental inhibition after α- and β-adrenergic blocker application mimicked developmental changes with reserpine. Using several methodological approaches our data suggest that reserpine inhibits cardiac differentiation. Thus catecholamines play a critical role during development.

알츠하이머질환 모델동물인 Tg2576마우스의 행동, Aβ-42 침적, 신경성장인자 대사에 미치는 reserpine의 영향

Reserpine은 항고혈압제로서 알츠하이머질병의 증상을 나타내는 Caenorhabditis elegans에서 세포독성을 감소시켜 마비를 억제하고 수명을 연장시키는 것으로 알려져 있다. 본 연구에서는 이러한 reserpine의 효능을 포유동물에서 확인하기 위하여, 알츠하이머질병의 병리적 특성과 연관된 주요인자의 변화를 30일 동안 reserpine을 투여한 Tg2576 마우스에서 관찰하였다. 그 결과, 공격행동(aggressive behavior)은 vehicle 투여 그룹에 비하여 reserpine 투여 그룹에서 유의적으로 감소하였으나 사회적 접촉(social contact)은 유의적인 변화가 없었다. 뇌의 해마부분에서 알츠하이머질병의 원인 중 하나인 <TEX>$A{\beta}$</TEX>-42의 축적은 reserpine 투여 그룹에서 유의적으로 감소하였고, <TEX>$A{\beta}$</TEX>-42의 농도도 대조군에 비하여 reserpine 투여 그룹에서 감소하였다. 더불어, <TEX>${\gamma}$</TEX>-secretase의 구성단백질 중에서 PS-2, Pen-2, APH-1의 발현은 대조군에 비하여 reserpine 투여군에서 유의적으로 감소하였으나 NCT 발현은 변화가 없었다. 혈청에서 NGF의 농도는 Tg2576 마우스에서 감소하였다가 reserpine 투여한 그룹에서 유의적으로 증가하였으며, high affinity receptor의 신호전달과정에 포함된 단백질 중에서 reserpine 투여 그룹은 TrkA의 인산화가 증가하고 ERK 인산화는 감소되었다. 한편 low affinity receptor의 신호전달과정에서, <TEX>$p75^{NTR}$</TEX>과 Bcl-2의 발현은 vehicle 그룹에 비하여 reserpine 투여 그룹에서 유의적으로 발현이 증가하였으나 RhoA의 발현은 reserpine 투여 그룹에서 감소하였다. 따라서 이러한 결과는 reserpine은 포유동물 치매모델인 Tg2576 마우스에서 행동학적 변화, <TEX>$A{\beta}$</TEX>-42의 축적, NGF의 농도, NGF신호전달의 변화 등을 유도하며, 향후 치매치료제로서 가능성을 제시하고 있다. Reserpine, an anti-hypertensive drug, is able to positively modulate several phenotypes associated with <TEX>$A{\beta}$</TEX> toxicity in a Caenorhabditis elegans model of Alzheimer's disease (AD). We investigated into the therapeutic effects of reserpine on mammalian neurodegenerative disorders, and found that significant alteration of the key factors influencing AD was detected in Tg2576 mice after reserpine treatment for 30 days. The aggressive behavior of Tg2576 mice was significantly improved upon reserpine treatment, whereas their social contact was consistently maintained. Furthermore, the levels of <TEX>$A{\beta}$</TEX>-42 peptide in the hippocampus of the brain and blood serum were lower in the reserpine-treated group than in the vehicle-treated group. Among g-secretase components, the expression levels of PS-2, Pen-2, and APH-1 were slightly lower in reserpine-treated Tg2576 mice, although a significant change in nicastrin (NCT) expression was not detected. Furthermore, the serum level of nerve growth factor (NGF) increased in reserpine-treated Tg2576 mice compared with vehicle-treated mice. Among down-stream effectors of the NGF receptor TrkA signaling pathway, reserpine treatment induced elevation of TrkA phosphorylation and reduction of ERK phosphorylation. In addition, in the NGF receptor <TEX>$p75^{NTR}$</TEX> signaling pathway, the expression levels of <TEX>$p75^{NTR}$</TEX> and Bcl-2 were enhanced in reserpine-treated Tg2576 mice compared with vehicle-treated mice, whereas the expression level of RhoA declined. Overall, these results suggest that reserpine can help relieve AD pathogenesis in Tg2576 mice through downregulation of <TEX>$A{\beta}$</TEX>-42 deposition, alteration of <TEX>${\gamma}$</TEX>-secretase components, and regulation of NGF metabolism.

Effects of reserpine on reproduction and serotonin immunoreactivity in the stable fly Stomoxys calcitrans (L.)

Biogenic amines are known to play critical roles in key insect behaviors such as feeding and reproduction. This study documents the effects of reserpine on mating and egg-laying behaviors of the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), which is one of the most significant biting fly pests affecting cattle. Two sperm staining techniques were adapted successfully to reveal the morphology of stable fly sperm, for the first time, and determine successful mating in females through the assessment of sperm transfer. This approach was also applied to assess sperm transfer by males treated with different doses of reserpine. Mating or sperm transfer did not occur in flies during the first 3days after emergence. Thereafter, the percentage of females that mated increased with age. Reserpine treatment of males reduced sperm transfer in a dose-dependent manner. Older males were more sensitive to reserpine treatment than younger flies. Reserpine treatment of 5days old females reduced the number of eggs laid, but had no effect on egg-hatching rates. Results of immunoreactivity (IR) experiments indicated that serotonin in the neuronal processes innervating male testes was completely depleted by reserpine within 5h after treatment. This effect was transient as the serotonin immunoreactive signal was recovered in 33.3% of the males at 1day post-treatment and in 94.4% of the flies at 3days post-treatment. The results of this study concur with previous findings in other insect species and extend our knowledge of the critical roles biogenic amines play in mating and oviposition behaviors of the stable fly. The work could provide a foundation to further characterize the specific roles of individual biogenic amines and their receptors in stable fly reproduction.