Centella asiatica (L.) Urb. Extract ameliorates branched-chain amino acid (BCAA) metabolism in acute reserpine-induced stress zebrafish model via 1H Nuclear Magnetic Resonance (NMR)-based metabolomics approach

Depression is a common mental disorder that can adversely affect psychosocial function and quality of life. However, the exact aetiology and pathogenesis of depression are still unclear. Stress plays a major role in the pathogenesis of depression. The use of currently prescribed antidepressants has many side effects. Centella asiatica (C. asiatica) has shown promising antidepressant activity in rodent models. Here, we developed a reserpine-induced zebrafish stress-like model and performed behavioural analysis, cortisol measurement and ¹H-Nuclear Magnetic Resonance (¹H NMR) spectroscopy-based metabolomics analysis to test the anti-stress activity of ethanolic extract of C. asiatica (RECA). A significant increase in total distance travelled (F_(8,8) = 8.905, p = 0.0054) and a reduction in freezing duration (F_{(9, 9)} = 10.38, p = 0.0018) were found in the open field test (OFT). Asiaticoside, one of tested C.asiatica's triterpenoid gives a significant increase in contact duration (F_(5,5) = 142.3, (p = 0.0330) at 2.5 mg/kg). Eight biomarkers were found, i.e. ß-hydroxyisovaleric acid, leucine, threonine, scylloinositol, lactate, betaine, valine, choline and l-fucose, to be responsible for the class separation between stress and RECA-treated groups. Metabolic pathway alteration in zebrafish brain upon treatment with RECA was identified as valine, leucine and isoleucine biosynthesis, while alanine, aspartate, glutamate and glycerophospholipid metabolism was involved after fluoxetine treatment.

Label-free quantitative proteomic analysis of reserpine-induced depression in mice intervened by berberine

Proteomic analysis of reserpine-induced depression and the effects of berberine on this were investigated to delineate the possible underlying mechanism. Reserpine was used for the model of behavioral depression. Model mice were treated with berberine. Mice brain proteomic analysis was carried out by label-free nano LC-ESI-OrbiTrap MS/MS technology. The data were processed by Maxquant software. The differentially-expressed proteins were evaluated on GO and KEGG analysis, and key protein expression was validated by Western blot analysis. A total of 278 differentially-expressed proteins were identified. Reserpine could cause cerebral injury and depressive disorder in mice, the mechanism of which is related to steroid hormone biosynthesis, chemical carcinogenesis, nucleotide excision repair and the retinoic acid-inducible gene I-like (RIG-I-like) receptor signaling. Berberine treatments involve 3 distinct proteins in the RIG-I-like receptor signaling. RIG-I was validated, which was over-expressed in the model group and negative in the normal and administration groups. RIG-I mediated neuroinflammation could participate in the process of depression and RIG-I may become a target for berberine against depression.

Effects of bee venom and dopamine-loaded nanoparticles on reserpine-induced Parkinson's disease rat model

Parkinson's disease (PD) is a progressive chronic neurodegenerative condition characterized by the loss of dopaminergic neurons within the substantia nigra. Current PD therapeutic strategies are mainly symptomatic and can lead to motor complications overtime. As a result, alternative medicine may provide an effective adjuvant treatment for PD as an addition to or as a replacement of the conventional therapies. The aim of this work was to evaluate the effects of Bee Venom (BV) and dopamine (DA)-loaded nanoparticles in a reserpine-induced animal model of PD. After inducing PD with reserpine injection, different groups of male rats were treated with L-Dopa, BV, DA-nanoparticles. Our findings showed that BV and DA-nanoparticles administration restored monoamines, balanced glutamate/GABA levels, halted DNA fragmentation, decreased pro-inflammatory mediators (IL-1β and TNF-α), and elevated anti-inflammatory mediators (PON1) and neurotropic factor (BDNF) levels in comparison with conventional therapy of PD. Furthermore, in a reserpine-induced PD rat model, the ameliorative effects of BV were significantly superior to that of DA-nanoparticles. These findings imply that BV and DA-nanoparticles could be useful as adjuvant treatments for PD.

Tryptophan lessens reserpine induced anxiety, depression and memory impairment by modulating oxidative stress and serotonergic activity

Reserpine (Res)-induced depletion of monoamines and altered neurotransmission and produces oxidative stress. Tryptophan (TRP) regulated the serotonin neurotransmission. Because systemically injected Res induced behavioral deficits and oxidative stress, while, dietary components prevented these adverse effects, we used TRP a pharmacological tool to prevent Res- induced changes in behavior, memory impairments, oxidative stress and regulation of serotonin neurotransmission in rats. Anxiolytic, antidepressant, cognitive functions, lipid peroxidation, antioxidant enzymes serotonin metabolism were studied in Res and vehicle treated animals following administration of 50 and 100 mg/ml/kg of tryptophan. Following administration of TRP [50 and 100mg/ml/kg], Res induced anxiety-and/or depression like behaviors normalized. Res-induced impaired cognitive function and increased acetylcholinesterase activity also improved following administration of TRP at both doses. Res induced increased brains' malondialdehyde (MDA) and decreased antioxidant enzymes activity also normalized by TRP. Res-induced decreased 5-HT metabolism also regulated by administration of TRP at both doses. In conclusion it can be recommended that administration/supplementation of TRP in daily life can aid in battling the anxiety, depression, modulating serotonergic activity and oxidative stress. Study also exhibits the anti-acetylcholinesterase role of TRP which may be possible reason for improved cognition following stress situation.

Effects of CATECHIN on reserpine-induced vacuous chewing movements: behavioral and biochemical analysis

This study evaluated the effect of (+)-catechin, a polyphenolic compound, on orofacial dyskinesia (OD) induced by reserpine in mice. The potential modulation of monoaminoxidase (MAO) activity, tyrosine hydroxylase (TH) and glutamic acid decarboxylase (GAD67) immunoreactivity by catechin were used as biochemical endpoints. The interaction of catechin with MAO-A and MAO-B was determined in vitro and in silico. The effects of catechin on OD induced by reserpine (1 mg/kg for 4 days, subcutaneously) in male Swiss mice were examined. After, catechin (10, 50 or 100 mg/kg, intraperitoneally) or its vehicle were given for another 20 days. On the 6th, 8th, 15th and 26th day, vacuous chewing movements (VCMs) and locomotor activity were quantified. Biochemical markers (MAO activity, TH and GAD67 immunoreactivity) were evaluated in brain structures. In vitro, catechin inhibited both MAO isoforms at concentrations of 0.34 and 1.03 mM being completely reversible for MAO-A and partially reversible for MAO-B. Molecular docking indicated that the catechin bound in the active site of MAO-A, while in the MAO-B it interacted with the surface of the enzyme in an allosteric site. In vivo, reserpine increased the VCMs and decreased the locomotor activity. Catechin (10 mg/kg), decreased the number of VCMs in the 8th day in mice pre-treated with reserpine without altering other behavioral response. Ex vivo, the MAO activity and TH and GAD67 immunoreactivity were not altered by the treatments. Catechin demonstrated a modest and transitory protective effect in a model of OD in mice.

Chronic Pregabalin Treatment Ameliorates Pain, but not Depressive-Like Behaviors, in a Reserpine-Induced Myalgia Model in Rats

BACKGROUND

Anticonvulsants are often prescribed as coanalgesics for pathologies presenting chronic pain, such as chronic neuropathic pain and fibromyalgia. These pathologies are associated with a wide range of comorbidities: chronic fatigue, cognitive impairment, sleep disturbances, and mood disorders. Pregabalin, an anticonvulsant used to treat fibromyalgia syndrome, has been proven to improve pain and fatigue symptoms. However, most studies have not considered the analytic effect of this drug on comorbid depressive-like symptoms in this syndrome.

OBJECTIVES

The main study objective was to examine the role of pregabalin in depressive symptomatology comorbid to chronic widespread pain using a reserpine-induced myalgia model.

STUDY DESIGN

A randomized, controlled, animal study.

SETTING

Research and data analyses were performed at the GESADA laboratory, Department of Human Anatomy and Embryology, University of Valencia, Spain.

METHODS

Forty-six Sprague-Dawley male rats were used. Acute chronic pregabalin administration was tested for depressive-like behaviors (Forced Swimming and Novelty-Suppressed Feeding Tests) and for alteration of pain thresholds (tactile allodynia, Electronic Von Frey test; and mechanical hyperalgesia, Randall and Selitto test). The same procedures were followed with duloxetine as a positive control.

RESULTS

Pregabalin significantly improved depressive-like behaviors in acute, but not chronic treatment, and significantly ameliorated pain thresholds.

LIMITATIONS

Lack of histological and electrophysiological tests.

CONCLUSIONS

Pregabalin is not effective in depressive-like symptoms associated with chronic pain but might play an acute antidepressive-like role given its antinociceptive effect.

Developmental neurotoxicity of reserpine exposure in zebrafish larvae (Danio rerio)

Reserpine is widely used for treatment of hypertension and schizophrenia. As a specific inhibitor of monoamine transporters, reserpine is known to deplete monoamine neurotransmitters and cause decreased movement symptoms. However, how zebrafish larvae respond to reserpine treatment is not well studied. Here we show that swimming distance and average velocity are significantly reduced after reserpine exposure under various stimulatory conditions. Using liquid chromatograph-mass spectrometer analysis, decreased levels of monoamines (e.g. dopamine, noradrenaline, and serotonin) were detected in reserpine-treated larvae. Moreover, reserpine treatment significantly reduced the number of dopaminergic neurons, which was identified with th (Tyrosine Hydroxylase) in situ hybridization in the preoptic area. Interestingly, dopaminergic neuron development-associated genes, such as otpa, otpb, wnt1, wnt3, wnt5 and manf, were downregulated in reserpine treated larvae. Our data indicates that 2 mg/L reserpine exposure induces dopaminergic neuron damage in the brain, demonstrating a chemical induced depression-like model in zebrafish larvae for future drug development.

Evaluation of the Xpa-Deficient Transgenic Mouse Model for Short-Term Carcinogenicity Testing: 9-Month Studies with Haloperidol, Reserpine, Phenacetin, and D-Mannitol

As part of the international evaluation program coordinated by ILSI/HESI, the potential of DNA repair deficient Xpa- /- mice and the double knockout Xpa- /- .p53+ /- mice for short term carcinogenicity assays was evaluated. For comparison also wild-type C57BL/6 mice (WT) were included in these studies. Four test compounds were administered to groups of 15 male and 15 female Xpa- /- mice, Xpa- /- .p53+ /- mice and WT mice for 39 weeks. The model compounds investigated were haloperidol, reserpine (nongenotoxic rodent carcinogens, putative human noncarcinogens), phenacetin (genotoxic rodent carcinogen, suspected human carcinogen), and D-mannitol (noncarcinogen in rodents and humans). The test compounds were administered as admixture to rodent diet at levels up to 25 mg/kg diet for haloperidol, 7.5 mg/kg diet for reserpine, 0.75% for phenacetin, and 10% for D-mannitol. These levels included the maximum tolerable dose (MTD). Survival was not affected with any of the test compounds. Haloperidol, reserpine and D-mannitol were negative in the carcinogenicity assay with Xpa- /- and Xpa- /- .p53+ /- mice, showing low and comparable tumor incidences in controls and high-dose animals. The results obtained with phenacetin may be designated equivocal in Xpa- /- .p53+ /- mice, based on the occurrence of a single rare tumor in the target organ (kidney) accompanied by a low incidence of hyperplastic renal lesions and a high incidence of karyomegaly. These results are in agreement with the currently known carcinogenic potential of the 4 test compounds in humans.

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 0.7 mg/kg subcutaneous (s.c.)), every other day for 3 days), which was administered after (experiment 1) and before (experiment 2) magnesium (Mg) supplementation (40 mg/kg/mL, peroral (p.o.)). In experiment 1, Mg was administered for 28 days before reserpine treatment, while in experiment 2, it was initiated 24 h 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.

Molecular, Neurochemical, and Behavioral Hallmarks of Reserpine as a Model for Parkinson's Disease: New Perspectives to a Long-Standing Model

The administration of reserpine to rodents was one of the first models used to investigate the pathophysiology and screening for potential treatments of Parkinson's disease (PD). The reserpine model was critical to the understanding of the role of monoamine system in the regulation of motor and affective disorders, as well as the efficacy of current PD treatments, such as L-DOPA and dopamine agonists. Nevertheless, with the introduction of toxin-induced and genetic models of PD, reserpine became underused. The main rationale to this drawback was the supposed absence of reserpine construct validity with PD. Here, we highlight classical and recent experimental findings that support the face, pharmacological, and construct validity of reserpine PD model and reason against the current rationale for its underuse. We also aim to shed a new perspective upon the model by discussing the main challenges and potentials for the reserpine model of PD.

Attenuation of reserpine-induced pain/depression dyad by gentiopicroside through downregulation of GluN2B receptors in the amygdala of mice

Epidemiological studies demonstrate that pain frequently occurs comorbid with depression. Gentiopicroside (Gent) is a secoiridoid compound isolated from Gentiana lutea that exhibits analgesic properties and inhibits the expression of GluN2B-containing N-methyl-D-aspartate (NMDA) receptors in the anterior cingulate cortex of mice. However, the effects of Gent on the reserpine-induced pain/depression dyad and its underlying mechanisms are unclear. Reserpine administration (1 mg/kg subcutaneous daily for 3 days) caused a significant decrease in the nociceptive threshold as evidenced by the reduced paw withdrawal latency in response to a radiant heat source and mechanical allodynia. Behavioral detection indicated a significant increase in immobility time during a forced swim test, as well as decreased time in the central area and total travel distance in an open field test. Furthermore, reserpinized animals exhibited increased oxidative stress. Systemic Gent administration dose-dependently ameliorated the behavioral deficits associated with reserpine-induced pain/depression dyad. At the same time, the decrease in biogenic amine levels (norepinephrine, dopamine, and serotonin) was integrated with the increase in caspase-3 levels and GluN2B-containing NMDA receptors in the amygdala of the reserpine-injected mice. Gent significantly reversed the changes in the levels of biogenic amines, caspase-3, and GluN2B-containing NMDA receptors in amygdala. However, Gent did not affect the expression of GluN2A-containing NMDA receptors. The inhibitory effects of Gent on oxidative stress were occluded by simultaneous treatment of GluN2B receptors antagonist Ro25-6981. Our study provides strong evidence that Gent inhibits reserpine-induced pain/depression dyad by downregulating GluN2B receptors in the amygdala.

The effect of adenosine A(2A) receptor antagonists on hydroxyl radical, dopamine, and glutamate in the striatum of rats with altered function of VMAT2

It has been shown that a decreased vesicular monoamine transporter (VMAT2) function and the disruption of dopamine (DA) storage is an early contributor to oxidative damage of dopamine neurons in Parkinson's disease (PD). In our previous study, we demonstrated that adenosine A(2A) receptor antagonists suppressed oxidative stress in 6-hydroxydopamine-treated rats suggesting that this effect may account for neuroprotective properties of drugs. In the present study, rats were injected with reserpine (10 mg/kg sc) and 18 h later the effect of the adenosine A(2A) receptor antagonists 8-(3-chlorostyryl)caffeine (CSC) and 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385) on extracellular DA, glutamate and hydroxyl radical formation was studied in the rat striatum using in vivo microdialysis. By disrupting VMAT2 function, reserpine depleted DA stores, and increased glutamate and hydroxyl radical levels in the rat striatum. CSC (1 mg/kg) but not ZM 241385 (3 mg/kg) increased extracellular DA level and production of hydroxyl radical in reserpinised rats. Both antagonists decreased the reserpine-induced increase in extracellular glutamate. L-3,4-Dihydroxyphenylalanine (L-DOPA) (25 mg/kg) significantly enhanced extracellular DA, had no effect on reserpine-induced hydroxyl radical production and decreased extracellular glutamate concentration. CSC but not ZM 241385 given jointly with L-DOPA increased the effect of L-DOPA on extracellular DA and augmented the reserpine-induced hydroxyl radical production. CSC and ZM 241385 did not influence extracellular glutamate level, which was decreased by L-DOPA. It seems that by decreasing the MAO-dependent DA metabolism rate, CSC raised cytosolic DA and by DA autoxidation, it induced hydroxyl radical overproduction. Thus, the methylxanthine A(2A) receptor antagonists bearing properties of MAO-B inhibitor, like CSC, may cause a risk of oxidative stress resulting from dysfunctional DA storage mechanism in early PD.

Effects on neuroendocrinoimmune network of Lizhong Pill in the reserpine induced rats with spleen deficiency in traditional Chinese medicine

AIM OF THE STUDY

Lizhong Pill, composed of radix Ginseng (Panax ginseng C.A. Meyer), rhizoma Zingiberis (Zingiber officinale Roscoe), rhizoma Atractylodis Macrocephalae (Atractylodes macrocephala Koidz.) and radix Glycytthizae (Glycyrrhiza uralensis Fisch.), is a classical herbal product for curing spleen deficiency in traditional Chinese medicine (TCM), and reserpine treated rats show similar signs to TCM spleen deficiency pattern. This paper is aimed to explore the regulatory effect on neuroendocrinoimmune network by Lizhong Pill in reserpine induced TCM spleen deficiency rats.

MATERIALS AND METHODS

100 healthy adult male SD rats, with a mean weight of 200 g, were randomly divided into five groups in average: control group, reserpine treated group, atropine treated group, treatment groups with Lizhong Pill at high dose and low dose (equal to the dosage of crude drugs for 4 g/kg/d and 8 g/kg/d). Rats in reserpine treated group were induced by intraperitoneal injection of reserpine at 0.5 mg/kgd for 4 weeks. The levels of IL-1, IL-6 and gastrin were measured with radioimmunoassay, TNF-α and IFN-γ in serum were measured with ELISA, the level of vasoactive intestinal peptide (VIP) and substance P (SP) in small intestine were determined with radioimmunoassay, and the TNF-α and TGF-β positive cells in small intestine were detected by immunohistological staining. Data were analyzed with SAS 9.1 software package.

RESULTS

The rats in reserpine treated group, body weight, concentrations of IFN-γ, IL-1 and TNF-α in serum, expression of TGF-β in small intestine, VIP in small intestine decreased (P<0.05), and the level of IL-6 in serum, expression of TNF-α, SP in small intestine and gastrin were increased (P<0.05). Administration of Lizhong Pill at high dose could increase the body weights at day 21, and the weights of rats in Lizhong Pill groups were much higher compared to reserpine treated group. At high dose of Lizhong Pill could increase the level of TNF-α in serum. Lizhong Pill at high dose and low dose could reverse the changes of IL-1, IL-6 and IFN-γ, gastrin, expression of TGF-β and TNF-α, VIP and SP in small intestine.

CONCLUSIONS

The rats treated with reserpine, with similar signs to TCM spleen deficiency, show neuroendocrinoimmune disorders, and the restoration of the neuroendocrinoimmune disorders might be the part of mechanism of Lizhong Pill for reinforcing TCM spleen deficiency.

Further evidence for an involvement of nociceptin/orphanin FQ in the pathophysiology of Parkinson's disease: a behavioral and neurochemical study in reserpinized mice

The contribution of nociceptin/orphanin FQ (N/OFQ) to reserpine-induced Parkinsonism was evaluated in mice. A battery of motor tests revealed that reserpine caused dose-dependent and long-lasting motor impairment. Endogenous N/OFQ sustained this response because N/OFQ peptide (NOP) receptor knockout (NOP(-/-) ) mice were less susceptible to the hypokinetic action of reserpine than wild-type (NOP(+/+) ) animals. Microdialysis revealed that reserpine elevated glutamate and reduced GABA levels in substantia nigra reticulata, and that resistance to reserpine in NOP(-/-) mice was accompanied by a milder increase in glutamate and lack of inhibition of GABA levels. To substantiate this genetic evidence, the NOP receptor antagonist 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H benzimidazol-2-one (J-113397) simultaneously reduced akinesia and nigral glutamate levels in reserpinized NOP(+/+) mice, being ineffective in NOP(-/-) mice. Moreover, repeated J-113397 administration in reserpinized mice resulted in faster recovery of baseline motor performance which was, however, accompanied by a loss of acute antiakinetic response. The short-term beneficial effect of J-113397 was paralleled by normalization of nigral glutamate levels, whereas loss of acute response was paralleled by loss of the ability of J-113397 to inhibit glutamate levels. We conclude that endogenous N/OFQ contributes to reserpine-induced Parkinsonism, and that sustained NOP receptor blockade produces short-term motor improvement accompanied by normalization of nigral glutamate release.

Effect of Hibiscus rosa sinensis on reserpine-induced neurobehavioral and biochemical alterations in rats

Effect of methanolic extract of Hibiscus rosa sinensis (100-300 mg/kg) was studied on reserpine-induced orofacial dyskinesia and neurochemical alterations. The rats were treated with intraperitoneal reserpine (1 mg/kg, ip) for 3 days every other day. On day 5, vacuous chewing movements and tongue protrusions were counted for 5 min. Reserpine treated rats significantly developed vacuous chewing movements and tongue protrusions however, coadministration of Hibiscus rosa sinensis roots extract (100, 200 and 300 mg/kg, per orally) attenuated the effects. Biochemical analysis of brain revealed that the reserpine treatment significantly increased lipid peroxidation and decreased levels of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GSH), an index of oxidative stress process. Coadministration of extract significantly reduced the lipid peroxidation and reversed the decrease in brain SOD, CAT and GSH levels. The results of the present study suggested that Hibiscus rosa sinensis had a protective role against reserpine-induced orofacial dyskinesia and oxidative stress.

Hypothermia-related testicular toxicity of reserpine in mice

Local cooling of the testis was reported to cause testicular abnormality, but there is no information regarding the effect of whole body cooling, such as hypothermia on spermatogenesis. We investigated whether hypothermia would cause testicular toxicity in mice. Male mice were administered with a single intraperitoneal dose of 100mg/kg of reserpine. The rectal temperature decreased to 29 degrees C 6h post dosing and thereafter sustained at lower values (24-25 degrees C) until 96 h post dosing. The histopathological examination of the testis showed nuclear vacuolation of round spermatids at stages I-V in mice examined 24, 48, 72 and 96 h post dosing. The lesions were more severe in the groups examined 72 and 96 h post dosing than in the groups examined 24 and 48 h post dosing. These results suggested that hypothermia condition at lower than 30 degrees C and sustained for more than 18 h could induce nuclear vacuolation of round spermatids at stages I-V in the testis. In order to demonstrate that the testicular lesion in the reserpine-treated mice was induced by hypothermia, mice were given a single intraperitoneal dose of 100mg/kg of reserpine, and each dosed group was housed under different environmental conditions for 72 h; one consisted of housing the mice individually at room temperature, and the other consisted of housing the mice individually under heated condition. In the mice administered with reserpine and housed at room temperature, hypothermia below 30 degrees C with a minimal of 26 degrees C was observed for 66 h. In contrast, the mice administered with reserpine and housed under heated condition maintained the rectal temperature of 33-36 degrees C. Nuclear vacuolation of round spermatids at stages I-V in the testis was observed in reserpine-treated mice maintained at room temperature, but not in reserpine-treated mice kept under heated condition. These data strongly indicated that nuclear vacuolation of round spermatids at stages I-V observed in reserpine-treated mice was related to hypothermia.

Effect of acute administration of hydroalcohol extract of Ilex paraguariensis St Hilaire (Aquifoliaceae) in animal models of Parkinson's disease

Ilex paraguariensis St Hilaire (Aquifoliaceae) is a plant widely cultivated in South America and with various reputed medicinal properties that can be attributed to phenolic constituents of the leaves: caffeine, theophylline and theobromine, besides the flavonoids, quercetin and rutin. This study examined the antiparkinsonian activity of the hydroalcohol extract of Ilex paraguariensis in models of protection against cerebral injury induced by MPTP and reversal of the catatonia induced by reserpine in mice. The hydroalcohol extract prevented MPTP-induced hypolocomotion at doses of 250 and 500 mg/kg at the all time points observed and also prevented the reserpine-induced catalepsy at the same doses. The extract potentiated the effect of apomorphine in preventing catatonia, suggesting a non-dopaminergic activity, probably through antagonism of adenosine. In biochemical studies the hydroalcohol extract caused a significant decrease in the NO levels, exhibited a DPPH-scavenging ability and was effective in preventing the oxidation of deoxyribose. The results obtained suggest that the hydroalcohol extract of Ilex paraguariensis may have an antiparkinsonian profile in animal models, probably through its antioxidant activity and antagonist action on adenosine A(2A) receptors.

The sea urchin embryo, an invertebrate model for mammalian developmental neurotoxicity, reveals multiple neurotransmitter mechanisms for effects of chlorpyrifos: therapeutic interventions and a comparison with the monoamine depleter, reserpine

Lower organisms show promise for the screening of neurotoxicants that might target mammalian brain development. Sea urchins use neurotransmitters as embryonic growth regulatory signals, so that adverse effects on neural substrates for mammalian brain development can be studied in this simple organism. We compared the effects of the organophosphate insecticide, chlorpyrifos in sea urchin embryos with those of the monoamine depleter, reserpine, so as to investigate multiple neurotransmitter mechanisms involved in developmental toxicity and to evaluate different therapeutic interventions corresponding to each neurotransmitter system. Whereas reserpine interfered with all stages of embryonic development, the effects of chlorpyrifos did not emerge until the mid-blastula stage. After that point, the effects of the two agents were similar. Treatment with membrane permeable analogs of the monoamine neurotransmitters, serotonin and dopamine, prevented the adverse effects of either chlorpyrifos or reserpine, despite the fact that chlorpyrifos works simultaneously through actions on acetylcholine, monoamines and other neurotransmitter pathways. This suggests that different neurotransmitters, converging on the same downstream signaling events, could work together or in parallel to offset the developmental disruption caused by exposure to disparate agents. We tested this hypothesis by evaluating membrane permeable analogs of acetylcholine and cannabinoids, both of which proved effective against chlorpyrifos- or reserpine-induced teratogenesis. Invertebrate test systems can provide both a screening procedure for mammalian neuroteratogenesis and may uncover novel mechanisms underlying developmental vulnerability as well as possible therapeutic approaches to prevent teratogenesis.

Protective effects of amylin on reserpine-induced gastric damage in the rat

Here we show that the vasoactive peptide amylin protects against reserpine-induced gastric injury in the rat, resulting in lower score of gastric lesions. Hepatocyte growth factor (HGF), its c-Met receptor and cyclooxygenase-2 (COX-2) expression, usually increased in course of reserpine-induced gastric damage, was decreased in rats treated with amylin. Pretreatment with the specific amylin receptor antagonist AC187 abrogated the gastroprotective effects of amylin and restored high expression levels of HGF, c-Met and COX-2. Our data suggest that protective effects of amylin upon the gastric mucosa are specific and eventually involve modulation of HGF, c-Met and COX-2 expression.

[Effect of dry aspen bark extract on the motor function of gastrointestinal tract in mice]

Experiments on mice (both intact and those with reserpine induced gastric ulcers) showed that dry aspen bark (DAB) extract stimulated the motor gastric activity. The DAB preparation produced a moderate purgative effect.

Report of the IWGT working group on strategies and interpretation of regulatory in vivo tests I. Increases in micronucleated bone marrow cells in rodents that do not indicate genotoxic hazards

In vivo genotoxicity tests play a pivotal role in genotoxicity testing batteries. They are used both to determine if potential genotoxicity observed in vitro is realised in vivo and to detect any genotoxic carcinogens that are poorly detected in vitro. It is recognised that individual in vivo genotoxicity tests have limited sensitivity but good specificity. Thus, a positive result from the established in vivo assays is taken as strong evidence for genotoxic carcinogenicity of the compound tested. However, there is a growing body of evidence that compound-related disturbances in the physiology of the rodents used in these assays can result in increases in micronucleated cells in the bone marrow that are not related to the intrinsic genotoxicity of the compound under test. For rodent bone marrow or peripheral blood micronucleus tests, these disturbances include changes in core body temperature (hypothermia and hyperthermia) and increases in erythropoiesis following prior toxicity to erythroblasts or by direct stimulation of cell division in these cells. This paper reviews relevant data from the literature and also previously unpublished data obtained from a questionnaire devised by the IWGT working group. Regulatory implications of these findings are discussed and flow diagrams have been provided to aid in interpretation and decision-making when such changes in physiology are suspected.

Effect of BR-16A (Mentat), a polyherbal formulation on drug-induced catalepsy in mice

Parkinson's disease (PD) is a neurodegenerative disease characterized by the selective loss of dopamine (DA) neurons of the substantia nigra pars compacta (SNc). The events, which trigger and/or mediate the loss of nigral DA neurons, however, remain unclear. Neuroleptic-induced catalepsy has long been used as an animal model for screening drugs for Parkinsonism. Administration of haloperidol (1 mg/kg, ip) or reserpine (2 mg/kg, ip) significantly induced catalepsy in mice. BR-16A (50 and 100 mg/kg, po), a polyherbal formulation or ashwagandha (50 and 100 mg/kg, po), significantly reversed the haloperidol or reserpine-induced catalepsy. The results indicate that BR-16A or ashwagandha has protective effect against haloperidol or reserpine-induced catalepsy and provide hope that BR-16A could be used in preventing the drug-induced extrapyramidal side effects and may offer a new therapeutic approach to the treatment of Parkinson's disease.

D2 dopamine receptors colocalize regulator of G-protein signaling 9-2 (RGS9-2) via the RGS9 DEP domain, and RGS9 knock-out mice develop dyskinesias associated with dopamine pathways

Regulator of G-protein signaling 9-2 (RGS9-2), a member of the RGS family of G GTPase accelerating proteins, is expressed specifically in the striatum, which participates in antipsychotic-induced tardive dyskinesia and in levodopa-induced dyskinesia. We report that RGS9 knock-out mice develop abnormal involuntary movements when inhibition of dopaminergic transmission is followed by activation of D2-like dopamine receptors (DRs). These abnormal movements resemble drug-induced dyskinesia more closely than other rodent models. Recordings from striatal neurons of these mice establish that activation of D2-like DRs abnormally inhibits glutamate-elicited currents. We show that RGS9-2, via its DEP domain (for Disheveled, EGL-10, Pleckstrin homology), colocalizes with D2DRs when coexpressed in mammalian cells. Recordings from oocytes coexpressing D2DR or the m2 muscarinic receptor and G-protein-gated inward rectifier potassium channels show that RGS9-2, via its DEP domain, preferentially accelerates the termination of D2DR signals. Thus, alterations in RGS9-2 may be a key factor in the pathway leading from D2DRs to the side effects associated with the treatment both of psychoses and Parkinson's disease.

Adrenomedullin modulates COX-2 and HGF expression in reserpine-injuried gastric mucosa in the rat

Here we show the increased hepatocyte growth factor (HGF) and cyclooxygenase-2 (COX-2) expression in gastric mucosa of rats which have developed a reserpine-induced ulcer. Such an increase of HGF and COX-2 expression was blunted in rats pretreated with adrenomedullin. Pretreatment with adrenomedullin and the adrenomedullin22-52 fragment did not result in changes of HGF and COX-2 expression, compared to the reserpine and adrenomedullin treated group. Pretreatment with adrenomedullin and the calcitonin gene-related peptide8-37 fragment (CGRP8-37) increased HGF and COX-2 expression, compared to the reserpine and adrenomedullin treated group. Our results suggest that the inhibitory effect of adrenomedullin on the expression of HGF and COX-2 is mediated by CGRP receptors.

Beneficial effects of vitamin C and vitamin E on reserpine-induced oral dyskinesia in rats: Critical role of striatal catalase activity

Oral dyskinesias are implicated in a series of neuropathologies and have been associated to an increase in oxidative stress. Several antioxidants, including vitamin E, decrease reserpine-induced oral dyskinesia (OD) in rodents and we have described a protective role of striatal catalase against the development of OD. The aim of this study was to verify the effects of vitamin C alone or in combination with vitamin E on reserpine-induced OD as well as to determine a possible role of catalase in the antidyskinetic property of these vitamins. Different doses of vitamin C attenuated reserpine-induced increase in OD. A similar treatment with an effective dose of vitamin C concomitant to an effective dose of vitamin E potentiated the antidyskinetic effect of both vitamins when administered alone. The administration of these vitamins alone produced an increase in striatal catalase activity that likewise was potentiated by their combined administration. In addition, the antidyskinetic property of vitamin E and vitamin C was abolished by a concomitant treatment with the catalase inhibitor aminotriazole. These results indicate a beneficial effect of these vitamins and reinforce the critical role of striatal catalase against the development of oral dyskinesias.

Effects of gabaergic drugs on reserpine-induced oral dyskinesia

Recently we have described the antidyskinetic property of the GABA mimetic drugs valproic acid and topiramate on reserpine-induced oral dyskinesia. In this respect, oral dyskinesia has been associated with important neuropathologies. The present study investigates the effects of different doses of the GABA(A) agonist tetrahydroisoxazolopyridine (THIP), of the GABA(B) agonist baclofen as well as of the GABA(A) modulator diazepam on the manifestation of reserpine-induced orofacial dyskinesia. Male Wistar rats received two injections of vehicle or of 1mg/kg reserpine separated by 48 h. Twenty-four hours later, animals were acutely treated with vehicle or THIP (2, 4 or 8 mg/kg), baclofen (1, 2 or 4 mg/kg) or diazepam (1, 2 or 4 mg/kg) and were observed for quantification of oral dyskinesia and open-field general activity. In order to verify the effects of these drugs per se on spontaneous oral movements, male Wistar rats were acutely treated with vehicle, 8 mg/kg THIP, 4 mg/kg baclofen or 4 mg/kg diazepam and observed for quantification of oral dyskinesia. The two highest doses of THIP or of baclofen abolished the manifestation of reserpine-induced oral dyskinesia while the lowest dose of baclofen attenuated it. Diazepam did not modify reserpine-induced oral dyskinesia at any dose tested. The highest doses of these drugs did not modify spontaneous oral movements. Reserpine-induced decrease in open-field general activity was not modified by any of the doses of THIP and diazepam or by the two lowest doses of baclofen. The highest dose of baclofen potentiated the increase in the duration of immobility induced by reserpine. These results reinforce the involvement of GABAergic hypofunction in the expression of oral dyskinesias, and support the potential therapeutic use of THIP and baclofen in the treatment of oral dyskinesias.

Effects of topiramate on oral dyskinesia induced by reserpine

Recently, we have described the antidyskinetic property of the GABA mimetic drug valproic acid on reserpine-induced oral dyskinesia, an animal model that has been related to tardive as well as acute dyskinesias, which are associated with important neuropathologies. The present study investigates the effects of different doses of the GABA mimetic anticonvulsant topiramate on the manifestation of reserpine-induced orofacial dyskinesia. Female EPM-M1 mice received two injections of control solution or of 0.5 mg/kg reserpine separated by 48 h. Twenty-four hours after the second reserpine or control solution injection, animals were acutely treated with control solution or topiramate (1, 3, 10 or 30 mg/kg) and were observed for quantification of oral dyskinesia or general activity in an open-field. In order to verify the effects of topiramate per se on oral dyskinesia or general activity, female EPM-M1 mice were acutely treated with control solution or 1, 3, 10 or 30 mg/kg topiramate and observed for quantification of oral dyskinesia and general activity. The highest dose of topiramate completely abolished the manifestation of reserpine-induced oral dyskinesia whereas the doses of 3 and 10 mg/kg significantly attenuated it. None of the doses of the anticonvulsant modified spontaneous locomotion frequency or oral movements, whereas spontaneous rearing frequency was decreased by 3, 10 and 30 mg/kg topiramate. The highest dose of topiramate did not modify general activity in reserpine-treated mice. These results support the potential therapeutic use of topiramate in the treatment of oral dyskinesias.

Effects of age on reserpine-induced orofacial dyskinesia and possible protection of diphenyl diselenide

Acute reserpine administration produces persistent oral dyskinesia in rats, an alleged animal model of tardive dyskinesia. The pathophysiology of the syndrome remains unclear, but experimental evidence suggests that neurodegeneration in the basal ganglia caused by oxidative stress plays a pivotal role in TD development. In this paper, the authors examined whether diphenyl diselenide, an organochalcogen with antioxidant properties, changes the behavioral and neurochemical effect of acute reserpine administration in old rats. The basal vacuous chewing movements (VCMs) and facial twitching (FT) duration was higher in old rats (15 months of age), when compared with adult rats (3 months of age; 0.01). Basal thiobarbituric acid-reactive species (TBARS) levels were increased only in the cortex of old rats, when compared to adult animals (p < .05). Reserpine injection (1mg/kg, s.c. for 3 days every other day) caused a significant increase on the tongue protusion (TP) frequency (p < .01) and facial twitching duration (p < .01) in old rats. Diphenyl diselenide (10 mg/kg, i.p. for 4 days, starting the day before reserpine) reversed only reserpine-induced TP increase (p < .01). Reserpine caused a significant increase in striatal TBARS levels (p < .01) and diselenide reversed (p < .01) the effect of reserpine on TBARS levels in the striatum. In subcortical parts, isolated reserpine or diselenide administration significantly increased (p < .01) the levels of TBARS, while simultaneous treatment with reserpine and diselenide reverted this effect (p < .01). The results of the present study confirmed the effects of age on orofacial dyskinesia. Diphenyl diselenide, an organochalcogen with antioxidant properties, showed modest effects on reserpine-induced orofacial dyskinesia. However, additional studies are still necessary to establish whether this compound can be considered an effective antioxidant in other models of neurotoxicity.

Reduction of Vascular Noradrenaline Sensitivity by AT 1 Antagonists Depends on Functional Sympathetic Innervation

Blockade of angiotensin II type-1 (AT 1 ) receptors has been shown to reduce the magnitude of the blood pressure response to noradrenaline in pithed rats via an unidentified mechanism. Dose-response curves were established for the noradrenaline-induced (10 −12 to 10 −7 mol/kg) increase of diastolic blood pressure in pithed rats treated with tubocurarine, propranolol, and atropine. Candesartan (1 mg/kg) increased the ED 50 of the noradrenaline response (1.3±0.1 nmol/kg) up to 20-fold. Vasopressor responsiveness to noradrenaline was attenuated specifically, whereas the vasopressin-induced increase in diastolic blood pressure was maintained. Specific involvement of AT 1 receptors was confirmed by equivalent actions of losartan. Blockade of norepinephrine transporter or α 2 -adrenoceptors using desipramine or rauwolscine reduced the losartan-induced shifts in the ED 50 values of noradrenaline by 63% and 21%, respectively. Combined blockade of norepinephrine transporter and α 2 -adrenoceptors eliminated the influence of losartan on noradrenaline sensitivity ( ED 50 5.5±1.3 versus 5.6±1.2 nmol/kg), a result also observed after sympathetic denervation by reserpine ( ED 50 7.1±0.8 versus 7.8±0.8 nmol/kg). Our experiments show that the reduction of vascular noradrenaline sensitivity by AT 1 blockade is dependent on the intact functioning of both neuronal noradrenaline uptake via norepinephrine transporter and presynaptic α 2 -mediated autoinhibition, exclusively provided by the sympathetic innervation. These newly identified mechanisms may contribute to the antihypertensive and protective actions of AT 1 blockers.

Effect of adrenomedullin on c-Met receptor expression after reserpine-induced gastric damage in the rat

Here, we show an increase in c-Met receptor expression during reserpine-induced gastric damage in the rat, as assessed by immunohistochemistry. Pretreatment of animals with adrenomedullin prevented this increase in c-Met expression. c-Met immunoreactivity was localized in gastric glands. c-Met immunoreactivity was associated with increased phosphorylation of c-Met receptor and extracellular signal-regulated kinase (ERK(1/2)). Our results suggest that both adrenomedullin and c-Met act as parallel defence mechanisms during pharmacologically induced gastric mucosa injury.

Reversal of Reserpine-Induced Orofacial Dyskinesia and Cognitive Dysfunction by Quercetin

Tardive dyskinesia (TD) is a serious neurological syndrome associated with long-term administration of neuroleptics to humans and experimental animals. The pathophysiology of this disabling and commonly irreversible movement disorder is still obscure. It may be caused by a loss of dopaminergic cells or may be due to free radicals as a product of high synaptic dopamine levels. Quercetin is a bioflavonoid with strong antioxidant properties. Repeated treatment with reserpine (1.0 mg/kg) on each other day for a period of 5 days (days 1, 3 and 5) significantly induced vacuous chewing movements (VCMs) and tongue protrusions (TPs) in rats. Chronic treatment with quercetin for a period of 4 weeks to reserpine-treated animals significantly and dose dependently (50 and 100 mg/kg) reduced the reserpine-induced VCMs and TPs. Reserpine-treated animals also showed poor retention of memory in elevated plus-maze task paradigm. Chronic quercetin administration significantly reversed reserpine-induced retention deficits. Biochemical analysis revealed that chronic reserpine treatment significantly induced lipid peroxidation and decreased the glutathione (GSH) levels in the brains of rats. Chronic reserpine-treated rats showed decreased levels of antioxidant defense enzymes, superoxide dismutase (SOD) and catalase. Chronic administration of quercetin dose dependently (50-100 mg/kg) and significantly reduced the lipid peroxidation and restored the decreased GSH levels by chronic reserpine treatment. It also significantly reversed the reserpine-induced decrease in brain SOD and catalase levels in rats. The results of the present study clearly indicated that quercetin has a protective role against reserpine-induced orofacial dyskinesia and memory impairment. Consequently, the use of quercetin as a therapeutic agent for the treatment of TD should be considered.

FK506 as effective adjunct to L-dopa in reserpine-induced catalepsy in rats

Reserpine-induced catalepsy is a widely accepted animal model of Parkinson's disease. In the present study reserpine (2.5 mg/kg, ip) 20 hr and alpha-mehyl-para-tyrosine (AMPT; 200 mg/kg, ip), one hour before the experiment induced significant catalepsy in rats as assessed by bar test. There was a significant increase in the time spent on the bar in bar test as compared to the control untreated rats. L-dopa (100 mg/kg, ip) and carbidopa (10 mg/kg, ip) combination, a conventional therapy was less effective in reversing reserpine-induced catalepsy. Pretreatment with FK506, a neuroprotectant (0.5-2 mg/kg, po) not only dose dependently reduced the catalepsy in reserpine-treated rats but a lower dose (1 mg/kg) potentiated the motor stimulant actions of sub threshold dose of L-dopa (100 mg/kg, ip) and carbidopa (10 mg/kg, ip) combination. Anticataleptic effect of FK506 was blocked dose dependently by specific D2 receptor blocker sulpiride (25-100 mg/kg, ip). In conclusion, the findings of the present study suggest that FK506 has an indirect modulatory action on the dopamine D2 receptors. FK506 being a neuroprotectant, could be used as an effective adjunct to L-dopa for the treatment of neuroleptic-induced extrapyramidal side effects.

Quercetin potentiates L-Dopa reversal of drug-induced catalepsy in rats: possible COMT/MAO inhibition

L-Dopa plus carbidopa treatment remains the first-line therapy in Parkinson's disease. The use of catechol-O-methyltransferase (COMT) and/or monoamine oxidase (MAO) inhibitors as an adjunct to L-dopa therapy has yielded varying degrees of success. Quercetin, a flavonoid present in many plants, is reported to inhibit COMT and MAO activities, the key enzymes involved in the metabolism of dopamine. In the present study we have studied the effect of quercetin on the L-dopa plus carbidopa combination against perphenazine and reserpine-induced catalepsy in rats. Neuroleptic-induced catalepsy is a widely accepted animal model for testing the drugs used in parkinsonism. Catalepsy in rats was induced by administration of perphenazine (5 mg/kg i.p.) or reserpine (2.5 mg/kg i.p.) + alpha-methyl-P-tyrosine (200 mg/kg i.p.). Catalepsy in animals was assessed by using the bar test. The quercetin dose (25-100 mg/kg, p.o.) dependently reversed perphenazine- as well as reserpine-induced catalepsy. When quercetin was combined with a subthreshold dose of L-dopa plus carbidopa, the anticatatonic effect was potentiated. Pretreatment with a central COMT inhibitor, 3,5-dinitrocatechol (OR-486) (10 mg/kg p.o.), or a MAO-B inhibitor, selegiline (5 mg/kg i.p.), also potentiated the actions of threshold dose of quercetin against perphenazine- or reserpine-induced catalepsy. On the other hand adenosine (100 mg/kg i.p.), which is known to decrease the release of catecholamines through an action on presynaptic A(1) receptors, partly reversed the protective effect of quercetin against perphenazine-induced catalepsy. Quercetin through its COMT and MAO enzyme-inhibiting properties might potentiate the anticatatonic effect of L-dopa plus carbidopa treatment. The results of the present study strongly suggest that quercetin could serve as an effective adjunct to L-dopa therapy in Parkinson's disease.

Effects of adrenomedullin on the contraction of gastric arteries during reserpine-induced gastric ulcer

Adrenomedullin (100 ng/kg, s.c.) prevents reserpine-induced damage of gastric mucosa. In the model of in vitro gastric arteries from reserpine-treated rats, adrenomedullin pre-treatment resulted in a decrease of the vasoconstriction in response to 5-hydroxytryptamine. In contrast, adrenomedullin pre-treatment of rat with intact gastric mucosa did not affect the vasoconstriction to 5-hydroxytryptamine. In the presence of the NOS inhibitor N(G)-nitro-L-arginine, the responsiveness to 5-hydroxytryptamine in gastric arteries from rats treated with reserpine + adrenomedullin was enhanced to the same level of rats treated with reserpine alone. The anti-ulcer effect of adrenomedullin could therefore be related, at least in part, to an increase of blood flow at the gastric mucosa, by a mechanism involving nitric oxide.

Pharmacological properties of the anti-Parkinson drug rasagiline; modification of endogenous brain amines, reserpine reversal, serotonergic and dopaminergic behaviours

Rasagiline [N-propargyl-1R(+)-aminoindan; TVP1012] is a potent irreversible monoamine oxidase (MAO) inhibitor with selectivity for type B of the enzyme, which is being developed for treatment of Parkinson's disease. In this study we examined effects of rasagiline on CNS monoamine levels, modification of behavioural response to L-tryptophan, fluoxetine and L-DOPA, and reversal of reserpine syndrome. Reserpine-induced ptosis was reversed by rasagiline at doses above 2 mg x kg(-1) i.p., which inhibit MAO-A as well as MAO-B, but not at MAO-B-selective doses. However, combination of rasagiline (10 mg x kg(-1) i.p.) with L-DOPA or L-tryptophan (50 mg x kg(-1) i.p.), or rasagiline (10 mg x kg(-1) p.o.) with fluoxetine (10 mg x kg(-1) p.o.), did not induce the behavioural hyperactivity syndrome which is seen following inhibition of both MAO-A and MAO-B by tranylcypromine together with the monoamine precursors. Following oral administration, levels of noradrenaline (NA), 5-hydroxytryptamine (5-HT) and dopamine (DA) were unaffected in hippocampus and striatum after single doses of rasagiline up to 2 mg x kg(-1). Following chronic oral administration (21 days, one dose daily), levels of NA, 5-HT and DA in hippocampus and striatum were unaffected by rasagiline at doses up to 1 mg x kg(-1). Rasagiline does not modify CNS monoamine tissue levels or monoamine-induced behavioural syndromes at doses which selectively inhibit MAO-B but not MAO-A.

The mitochondrial toxin 3-nitropropionic acid aggravates reserpine-induced oral dyskinesia in rats

The effects of a previous long-term administration of the mitochondrial toxin 3-nitropropionic acid were studied on an animal model of tardive dyskinesia, i.e., the frequency of spontaneous tongue protrusions in rats repeatedly treated with reserpine. 3-Nitropropionic acid (10 or 15 mg/kg i.p., every other day for 17 days) potentiated the increase in tongue-protrusion frequency induced by reserpine (1 mg/kg, s.c., every other day for 3 days) but did not modify reserpine-induced increase in immobility duration and decrease in locomotion frequency. These results support the notion that neurotoxic events are associated with the development of tardive dyskinesia.

Nitecapone and selegiline as effective adjuncts to L-DOPA in reserpine-induced catatonia in mice

Reserpine-induced catatonia is a widely accepted animal model of Parkinson's disease. In the present study, reserpine (5 mg/kg i.p.) and alpha-methylpara-tyrosine (AMPT) (200 mg/kg i.p.) induced catatonia in mice 20 h and 1 h before the experiment, respectively, as assessed using the rota-rod and bar tests after reserpine treatment. There was a significant decrease in fall-off time in the rota-rod test and a significant increase in time spent on the bar in the bar test as compared to the untreated control mice. Combination therapy with L-DOPA (100 mg/kg i.p.) and carbidopa (10 mg/kg i.p.) was less effective in reversing catatonia as compared to higher doses of L-DOPA (200 mg/kg i.p.) and carbidopa (20 mg/kg i.p.), which showed intense hyperactivity in reserpinized mice. Pretreatment with nitecapone (30 mg/kg i.p.), a COMT inhibitor, or selegiline (10 mg/kg i.p.), a MAO-B inhibitor potentiated the motor stimulant actions of subthreshold doses of the L-DOPA (100 mg/kg i.p.) and carbidopa (10 mg/kg i.p.) combination. Amantadine (40 mg/kg i.p.), but not bromocriptine, potentiated the effects of L-DOPA treatment. The NMDA antagonistic action of amantadine may have beneficial effects. It is concluded that COMT and MAO-B enzymes play an important role in the metabolism of dopamine and administration of a COMT or MAO-B inhibitor may prove to be a better adjunct to L-DOPA therapy than a dopamine receptor agonist in Parkinson's disease.

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 7). Effects of reserpine in 2- and 4-weeks studies

To assess the efficacy of different period of treatment for evaluating male reproductive toxicity in rats, reserpine was subcutaneously administered on a daily basis to male Sprague-Dawley rats at dosages of 0.05, 0.1 or 0.2 mg/kg for 2 weeks or at dosages of 0.05 or 0.1 mg/kg for 4 weeks. At the end of the administration period the animals were sacrificed and sperm counts, organ weights and histopathological changes in the reproductive organs were examined. The sperm number in the caudal epididymis and genital organ weights were not affected by reserpine with either 2- or 4-weeks treatment. In the 4-weeks study, histopathological examination of the testes revealed retention of step 19 spermatids in the seminiferous tubules of stages IX to XII and decreased secretory content of the prostate in the 0.05 and 0.1 mg/kg groups. In the 2-weeks study, although no distinct histopathological changes were observed in the 0.05 mg/kg group, decreased secretory content of the prostate, apoptosis of spermatocytes in the seminiferous tubules of stage VII and cell debris of the epididymis were observed in the 0.1 and 0.2 mg/kg groups. These results suggested that 2-weeks treatment with reserpine is sufficient for detection of testicular toxicity, although higher dosage levels are appropriate than for 4-weeks treatment.

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 8). Effects of daily subcutaneous administration of reserpine on spermatogenesis for 2 and 4 weeks

To obtain information on the validity and the limitations of 2-weeks repeated-dose toxicity studies to detect effects on the male genital organs of rats, reserpine was administered daily at 0.05 and 0.1 mg/kg by subcutaneous injection to Crj:CD(SD)IGS male rats for 2 and 4 weeks (2-weeks and 4-weeks studies). In the 2-weeks study, suppression of body weight gain was observed in the reserpine 0.1 mg/kg group. In the 4-weeks study, suppression of body weight gain and a decrease in prostate weight were observed in the reserpine 0.1 mg/kg group. Slight to moderate retention of step 19 spermatids in the seminiferous tubules (stages IX-XI) was observed in a few animals of both the reserpine 0.05 and 0.1 mg/kg groups in both the 2- and 4-weeks studies. However, seminiferous tubule atrophy with degeneration of germ sells was observed sporadically not only in the reserpine groups but also in the control group, and this change might have been the cause of the spermatid retention. Therefore, we were unable to reach a clear conclusion with regard to whether it is possible to detect reserpine toxicity on spermatogenesis in rats after 2-weeks administration.

Microdialysates of amines and metabolites from core nucleus accumbens of freely moving rats are altered by dizocilpine

In vivo microdialysis combined with high performance liquid chromatography (HPLC) with electrochemical detection, was used to study the effect of MK-801 (0.1 mg/kg i.p.) on extracellular concentrations of dopamine (DA) 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), norepinephrine (NE) and DOPAC/DA ratio in intact, 6-hydroxydopamine (6-OHDA)-lesioned, DSP4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzyl-amine hydrochloride)-lesioned and reserpine-treated rats. The results revealed high basal DA (0.735+/-0.05 fmol/microl), DOPAC (195.93+/-20.18 fmol/microl) and NE (0.585+/-0.01 fmol/microl), low 5-HT (0.334+/-0.032 fmol/microl) and high DOPAC/DA ratio (265.11+/-20.73) in intact cACC. 6-OHDA alone (8 microg/2 microl) depleted DA (-66%), DOPAC (-65%), and NE (-62%). On the other hand, in desipramine (DMI)-pretreated rats, 6-OHDA induced a large depletion of DA (-94%), DOPAC (-97%) and reduced DOPAC/DA ratio (-73%), but increased NE to 142% of intact and 369% of 6-OHDA-lesioned rats. DSP4 (50 mg/kg) decreased NE (-97%), DOPAC (-75%) and DOPAC/DA ratio (-69%). Reserpine (5 mg/kg s.c.) significantly decreased DOPAC (-84%), DOPAC/DA ratio (-81%), 5-HT (-69%) and NE (-86%), but nonsignificantly increased DA. In the intact rats, MK-801 did not change DA, but increased DOPAC and DOPAC/DA ratio. In 6-OHDA-lesioned rats, MK-801 increased DA, whereas in 6-OHDA+DMI rats MK-801 additionally increased DOPAC and DOPAC/DA ratio. DSP4 and reserpine reduced the ability of MK-801 to increase DOPAC and DOPAC/DA ratio. MK-801 did not change NE concentration in dialysates collected from intact rats, but increased that from 6-OHDA+DMI-lesioned rats. In DSP4-lesioned and reserpine-treated rats, MK-801 increased NE but to a level lower than that observed in the intact rats. These results suggest that systemic administration of a low dose of MK-801, which induces profound locomotor stimulation without stereotypy, increases DOPAC and DOPAC/DA ratio in the cACC of intact rats, whereas it additionally increases the depleted DA and NE concentrations especially in 6-OHDA-lesioned rats pretreated with DMI.

Effects of chemically- and environmentally-induced hypothermia on micronucleus induction in rats

We investigated micronucleus induction in rats treated with chlorpromazine and reserpine, drugs that induce hypothermia. We administered chlorpromazine (31.3--250mg/kg) or reserpine (500--2000 mg/kg) intraperitoneally and measured temperature rectally. Chlorpromazine at 62.5-250mg/kg and reserpine at all doses significantly decreased rectal temperature, although the hypothermic response was weaker than previously reported in mice. Only chlorpromazine at 250mg/kg decreased rectal temperature transiently to <33 degrees C for 20h and induced a statistically significant increase in micronucleated polychromatic erythrocyte frequency. When rats treated with reserpine at 500mg/kg were exposed to an environmental temperature of 16 degrees C for 6, 12, or 24h to keep their body temperature under 33 degrees C, only the 24h treatment group significantly induced micronuclei. In addition, relatively large micronuclei (diameter of micronucleus> or = 1/4 diameter of cytoplasm) accounted for 33.0% of the induced micronuclei, suggesting that hypothermia affected the mitotic apparatus. The hypothermic response to chlorpromazine and reserpine was weaker in rats than in mice, and it was correspondingly more difficult to induce micronuclei in rats with those drugs.

Enhanced levels of endogenous cannabinoids in the globus pallidus are associated with a reduction in movement in an animal model of Parkinson's disease

In recent years, cannabinoid receptors and their endogenous ligands (endocannabinoids) have been identified within the brain. The high density of CB1 cannabinoid receptors within the basal ganglia suggests a potential role for endocannabinoids in the control of voluntary movement and in basal ganglia-related movement disorders such as Parkinson's disease. However, whether endocannabinoids play a role in regulating motor behavior in health and disease is unknown. Here we report the presence in two regions of the basal ganglia, the globus pallidus and substantia nigra, of the endocannabinoids 2-arachidonoylglycerol (2AG) and anandamide. The levels of the latter compound are approximately threefold higher than those previously reported in any other brain region. In the reserpine-treated rat, an animal model of Parkinson's disease, suppression of locomotion is accompanied by a sevenfold increase in the levels of the 2AG in the globus pallidus, but not in the other five brain regions analyzed. Stimulation of locomotion in the reserpine-treated rat by either of the two selective agonists of D2 and D1 dopamine receptors, quinpirole and R-(+/-)-3-allyl-6-chloro-7, 8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (Cl-APB), respectively, results in the reduction of both anandamide and 2AG levels in the globus pallidus. Finally, full restoration of locomotion in the reserpine-treated rat is obtained by coadministration of quinpirole and the selective antagonist of the cannabinoid CB1 receptor subtype, SR141716A. These findings indicate a link between endocannabinoid signaling in the globus pallidus and symptoms of Parkinson's disease in the reserpine-treated rat, and suggest that modulation of the endocannabinoid signaling system might prove useful in treating this or other basal ganglia-related movement disorders.

The group II metabotropic glutamate receptor agonist, DCG-IV, alleviates akinesia following intranigral or intraventricular administration in the reserpine-treated rat

1. This study examined whether activation of group II metabotropic glutamate (mGlu) receptors in the substantia nigra pars reticulata (SNr) could reverse akinesia in a rodent model of Parkinson's disease (PD). 2. Male Sprague Dawley rats, stereotaxically cannulated above either the SNr or third ventricle, were rendered akinetic by injection of reserpine (5 mg kg-1 s.c.). Eighteen hours later, the rotational behaviour induced by unilateral injection of the group II mGlu receptor agonist, (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV), was examined. 3. Following intranigral injection, DCG-IV (0.125-0.75 nmol in 0.1 microliter) produced a dose-dependent increase in net contraversive rotations (n = 6-8 animals per dose), reaching a maximum of 395 +/- 51 rotations 60 min-1 after 0.75 nmol. The effects of DCG-IV (0.5 nmol) were inhibited by 63.0 +/- 9.0% following 30 min pre-treatment with the group II mGlu receptor antagonist, (2S)-alpha-ethylglutamic acid (EGLU; 100 nmol in 0.2 microliter; n = 6). 4. Following intraventricular injection, DCG-IV (0.125-1.5 nmol in 2 microliters) produced a dose-dependent increase in bilateral locomotor activity (n = 6-7 animals per dose), reaching a maximum of 180 +/- 21 locomotor units 30 min-1 after 0.5 nmol. Pre-treatment with EGLU (200 nmol in 2 microliters) inhibited the effects of DCG-IV (0.5 nmol) by 68.2 +/- 12.3% (n = 5). 5. These data show that activation of group II mGlu receptors in the SNr provides relief of akinesia in the reserpinized rat model of PD. The reversal seen following intraventricular administration supports the likely therapeutic benefit of systemically-active group II mGlu receptor agonists in PD.

The adrenergic receptor agonist, clonidine, potentiates the anti-parkinsonian action of the selective kappa-opioid receptor agonist, enadoline, in the monoamine-depleted rat

1. The treatment of Parkinson's disease relies predominantly upon dopamine replacement therapy, usually with l-dihydroxyphenylalanine (L-DOPA). However, side-effects of long-term treatment, such as L-DOPA-induced dyskinesias can be more debilitating than the disease itself. Non-dopaminergic treatment strategies might therefore be advantageous. 2. The aim of this study was to investigate the potential anti-parkinsonian efficacy of the kappa-opioid receptor agonist, enadoline, and the alpha-adrenoreceptor agonist, clonidine, both alone or in combination, in the reserpine-treated rat model of Parkinson's disease. 3. Rats were treated with reserpine (3 mg kg-1), and experiments carried out 18 h later, at which time they exhibited profound akinesia (normal animals 1251+/-228 mobile counts h-1, reserpine-treated animals 9+/-2 mobile counts h-1). Both enadoline and clonidine increased locomotion in reserpine-treated rats in a dose-dependent manner. The maximum locomotor-stimulating effect of enadoline alone was seen at a dose of 0.2 mg kg-1 (208+/-63 mobile counts h-1). The maximum effect of clonidine was seen at a dose of 2 mg kg-1 (536+/-184 mobile counts h-1). 4. Co-administration of enadoline (0.1 mg kg-1) and clonidine (0.01 - 0.1 mg kg-1) at sub-threshold doses, synergistically increased locomotion. 5. The synergistic stimulation of locomotion in the reserpine-treated rat involved activation of kappa-opioid receptors and a combination of both alpha1 and alpha2-adrenoreceptors. 6. The results presented suggest a need for further studies on the potential of stimulating kappa-opioid and/or alpha-adrenoreceptors as a therapy for Parkinson's disease. Furthermore, the studies may offer potential mechanistic explanations of the ability of alpha2-adrenergic receptor antagonist to reduce L-DOPA-induced dyskinesia in Parkinson's disease.

Accumulation of membranes and photoreceptor degeneration in mouse retina

Ultrastructural response of photoreceptors to 10 days of treatment with reserpine and bromocryptine, and to 10 days of illumination, was studied. Treatment with isoproterenol was also applied in some experiments with continuous illumination. Treatment with bromocryptine and reserpine induced elongation of rod outer segments and accumulation of membranes in the subretinal space. Increased incidence of apoptosis but not of autophagocytosis was observed in both cases. Continuous illumination with or without treatment with isoproterenol was found to induce intracellular accumulation of membranes, autophagocytosis and apoptosis. Incidence of apoptosis was slightly decreased in the case of isoproterenol application. We conclude that intracellular or extracellular accumulation of membranes can function as the apoptotic trigger in photoreceptors. Triggering of apoptosis was not dependent on autophagocytosis. Possible role of membrane peroxidation in photoreceptor cell death is discussed.

Effects of single and multiple treatments with L-dihydroxyphenylalanine (L-DOPA) on dopamine receptor-G protein interactions and supersensitive immediate early gene responses in striata of rats after reserpine treatment or with unilateral nigrostriatal lesions

We studied effects of L-dihydroxyphenylalanine (L-DOPA) treatment in rats following reserpine treatment or unilateral 6-hydroxydopamine (6-OHDA) injections into medial forebrain bundle. Quantitative in situ hybridization for mRNA's coding for the zinc finger immediate early gene (IEG) zif/268 or Jun family IEG jun b revealed that single L-DOPA injections accentuated IEG expression 3- to 7-fold in the dopamine (DA)-depleted striatum. This increased IEG response did not derive from any alterations in DA receptor-G protein coupling, assayed by DA stimulation of 35S-guanosine-5' (gamma-thio) triphosphate (35S-GTP-gamma-S) binding to striatal sections. Reserpine treatment increased both basal and maximal striatal DA-stimulated 35S-GTP-gamma-S binding. The augmented IEG responses to single L-DOPA treatments involved dependency on both D1 and D2 receptors and acutely to N-methyl-D-aspartate (NMDA) channels. Repetitive L-DOPA treatments yielded persistently elevated (zif/268) or additionally up-regulated (jun b) IEG response in the denervated striatum and down-regulated IEG responses in the control striatum. Degraded L-DOPA responses and appearance of involuntary movements after chronic L-DOPA use in advanced Parkinson's disease may derive from these IEG changes.