Repeated treatment with a low dose of reserpine as a progressive model of Parkinson's disease

Animal models of early-stage Parkinson's disease and acute dopamine deficiency to study compensatory neurodegenerative mechanisms

Parkinson's disease is a common neurodegenerative disease characterized by a widely variety of motor and non-motor symptoms. While the motor deficits are only visible following a severe dopamine depletion, neurodegenerative process and some non-motor symptoms are manifested years before the motor deficits. Importantly, chronic degeneration of dopaminergic neurons leads to the development of compensatory mechanisms that play roles in the progression of the disease and the response to anti-parkinsonian therapies. The identification of these mechanisms will be of great importance for improving our understanding of factors with important contributions to the disease course and the underlying adaptive process. To date, most of the data obtained from animal models reflect the late, chronic, dopamine-depleted states, when compensatory mechanisms have already been established. Thus, adequate animal models with which researchers are able to dissect early- and late-phase mechanisms are necessary. Here, we reviewed the literature related to animal models of early-stage PD and pharmacological treatments capable of inducing acute dopamine impairments and/or depletion, such as reserpine, haloperidol and tetrodotoxin. We highlighted the advantages, limitations and the future prospective uses of these models, as well as their applications in the identification of novel agents for treating this neurological disorder.

Desipramine rescues emotional memory deficit induced by low doses of reserpine

Emotional memory deficit is a well-known complication in early Parkinson's disease. However, its molecular mechanism is still not well known. To address this issue, we examined the cue-related fear-conditioning task and long-term potentiation (LTP) of the thalamus to the lateral amygdala in rats treated with low doses of reserpine (Res). We found that low-dose Res treatment impaired emotional memory and LTP. We also found that exogenous upregulation of norepinephrine (NE) ameliorated the impairment of LTP by facilitating β-adrenergic receptors. Finally, acute treatment with NE or desipramine rescued the impaired emotional memory induced by a low-dose of Res. These results imply a pivotal role for NE in synaptic plasticity and associative fear memory in rats treated with low doses of Res and suggest that desipramine is a potential candidate for treating Parkinson's disease-related emotional memory deficit.

Carvacrol prevents impairments in motor and neurochemical parameters in a model of progressive parkinsonism induced by reserpine

Parkinson's disease (PD) is a neurodegenerative disease characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra pars compact (SNpc), with consequent depletion of dopamine in the striatum, which gives rise to the characteristic motor symptoms of PD. Although its etiology is unknown, several studies have suggested that oxidative stress plays a critical function in the pathophysiology of PD, and antioxidant agents could be helpful to slown down the dopaminergic neurodegeneration. Carvacrol (CA) is a phenolic monoterpene found in essential oils of many aromatic plants that presents antioxidant and neuroprotective effects. This study aimed to assess the effect of CA in a reserpine (RES)-induced rat model of PD. Male Wistar rats received 15 s.c. injections of 0.1 mg/kg RES or vehicle, every other day, concomitantly to daily i.p. injections of CA (12.5 or 25 mg/kg) or vehicle. Across the treatment, the animals were submitted to behavioral evaluation in the catalepsy test (performed daily), open field test (7th day) and assessment of vacuous chewing movements (12th, 20th and 30th days). Upon completion of behavioral tests, rats were perfused and their brains underwent tyrosine hydroxylase (TH) immunohistochemical analysis. Our results showed that CA (12.5 e 25 mg/kg) prevented the increase in catalepsy behavior and number of vacuous chewing movements, but failed to revert the decreased open-field locomotor activity induced by RES. In addition, CA in both doses prevented the decrease in TH immunostaining induced by RES in the SNpc and dorsal striatum. Taken together, our results suggest that CA shows a protective effect in a rat model of PD, preventing motor and neurochemical impairments induced by RES. Thus, the use of CA as a promising new strategy for the prevention and/or treatment of PD may be considered.

Multiple Administration of Endogenous Amines TIQ and 1MeTIQ Protects Against a 6-OHDA-Induced Essential Fall of Dopamine Release in the Rat Striatum: In Vivo Microdialysis Study

Parkinson’s disease (PD) represents one of the neurodegenerative disorders which are caused by degeneration of dopaminergic neurons in the nigrostriatal pathway. Different toxins, e.g., 6-hydroxydopamine (6-OHDA), are used to model PD in animals. 6-OHDA is a neurotoxin which damages catecholaminergic neurons via production of oxygen radicals. Tetrahydroisoquinolines (TIQs) are endogenous amines which are present in the mammalian brain. Some of them, like TIQ and 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ), demonstrate neuroprotective properties. These compounds act as reversible MAO inhibitors and this way block free radical formation. To continue our previous experiments, we evaluated the effect of acute and chronic treatment with TIQ and 1MeTIQ on locomotor/exploratory activity and the release of dopamine as well as its metabolite 3-methoxytyramine (3-MT) in the striatum of unilaterally 6-OHDA-lesioned and sham-operated rats using in vivo microdialysis methodology. Additionally, the changes in the concentration of tyrosine hydroxylase in the substantia nigra were measured. A unilateral 6-OHDA lesion in the substantia nigra produces a strong reduction in the release of dopamine (approx. 70%) and 3-MT (approx. 50%) in the rat striatum. This effect was completely inhibited by multiple administration of TIQ and 1MeTIQ. The results obtained from the in vivo microdialysis study suggest that multiple treatment with both endogenous amines, TIQ and 1MeTIQ, protects dopaminergic neurons against a 6-OHDA-induced deficit of dopamine release. Furthermore, these amines were able to maintain physiological functions of striatal dopamine neurons damaged by a unilateral 6-OHDA lesion.

Passiflora cincinnata Extract Delays the Development of Motor Signs and Prevents Dopaminergic Loss in a Mice Model of Parkinson's Disease

Passiflora cincinnata Masters is a Brazilian native species of passionflower. This genus is known in the American continent folk medicine for its diuretic and analgesic properties. Nevertheless, few studies investigated possible biological effects of P. cincinnata extracts. Further, evidence of antioxidant actions encourages the investigation of possible neuroprotective effects in animal models of neurodegenerative diseases. This study investigates the effect of the P. cincinnata ethanolic extract (PAS) on mice submitted to a progressive model of Parkinson's disease (PD) induced by reserpine. Male (6-month-old) mice received reserpine (0.1 mg/kg, s.c.), every other day, for 40 days, with or without a concomitant treatment with daily injections of PAS (25 mg/kg, i.p.). Catalepsy, open field, oral movements, and plus-maze discriminative avoidance evaluations were performed across treatment, and immunohistochemistry for tyrosine hydroxylase was conducted at the end. The results showed that PAS treatment delayed the onset of motor impairments and prevented the occurrence of increased catalepsy behavior in the premotor phase. However, PAS administration did not modify reserpine-induced cognitive impairments. Moreover, PAS prevented the decrease in tyrosine hydroxylase immunostaining in the substantia nigra pars compacta (SNpc) induced by reserpine. Taken together, our results suggested that PAS exerted a neuroprotective effect in a progressive model of PD.

Spontaneously Hypertensive Rats (SHR) Are Resistant to a Reserpine-Induced Progressive Model of Parkinson's Disease: Differences in Motor Behavior, Tyrosine Hydroxylase and α-Synuclein Expression

Reserpine is an irreversible inhibitor of vesicular monoamine transporter-2 (VMAT2) used to study Parkinson’s disease (PD) and screening for antiparkinsonian treatments in rodents. Recently, the repeated treatment with a low-dose of reserpine was proposed as a progressive model of PD. Rats under this treatment show progressive catalepsy behavior, oral movements and spontaneous motor activity decrement. In parallel, compared to Wistar rats, spontaneously hypertensive rats (SHR) are resistant to acute reserpine-induced oral dyskinesia. We aimed to assess whether SHR would present differential susceptibility to repeated reserpine-induced deficits in the progressive model of PD. Male Wistar and SHR rats were administered 15 subcutaneously (s.c.) injections of reserpine (0.1 mg/kg) or vehicle, every other day and motor activity was assessed by the catalepsy, oral movements and open field tests. Only reserpine-treated Wistar rats presented increased latency to step down in the catalepsy test and impaired spontaneous activity in the open field. On the other hand, there was an increase in oral movements in both reserpine-treated strains, although with reduced magnitude and latency to instauration in SHR. After a 15-day withdrawn period, both strains recovered from motor impairment, but SHR animals expressed reduced latencies to reach control levels. Finally, we performed immunohistochemistry for tyrosine hydroxylase (TH) and α-synuclein (α-syn) 48 h after the last injection or 15 days after withdrawn. Reserpine-treated animals presented a reduction in TH and an increase in α-syn immunoreactivity in the substantia nigra and dorsal striatum (dSTR), which were both recovered after 15 days of withdraw. Furthermore, SHR rats were resistant to reserpine-induced TH decrement in the substantia nigra, and presented reduced immunoreactivity to α-syn in the dSTR relative to Wistar rats, irrespective of treatment. This effect was accompanied by increase of malondaldhyde (MDA) in the striatum of reserpine-treated Wistar rats, while SHR presented reduced MDA in both control and reserpine conditions relative to Wistar strain. In conclusion, the current results show that SHR are resilient to motor and neurochemical impairments induced by the repeated low-dose reserpine protocol. These findings indicate that the neurochemical, molecular and genetic differences in the SHR strain are potential relevant targets to the study of susceptibility to PD.

Cannabidiol Prevents Motor and Cognitive Impairments Induced by Reserpine in Rats

Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa that presents antipsychotic, anxiolytic, anti-inflammatory, and neuroprotective effects. In Parkinson's disease patients, CBD is able to attenuate the psychotic symptoms induced by L-DOPA and to improve quality of life. Repeated administration of reserpine in rodents induces motor impairments that are accompanied by cognitive deficits, and has been applied to model both tardive dyskinesia and Parkinson's disease. The present study investigated whether CBD administration would attenuate reserpine-induced motor and cognitive impairments in rats. Male Wistar rats received four injections of CBD (0.5 or 5 mg/kg) or vehicle (days 2-5). On days 3 and 5, animals received also one injection of 1 mg/kg reserpine or vehicle. Locomotor activity, vacuous chewing movements, and catalepsy were assessed from day 1 to day 7. On days 8 and 9, we evaluated animals' performance on the plus-maze discriminative avoidance task, for learning/memory assessment. CBD (0.5 and 5 mg/kg) attenuated the increase in catalepsy behavior and in oral movements - but not the decrease in locomotion - induced by reserpine. CBD (0.5 mg/kg) also ameliorated the reserpine-induced memory deficit in the discriminative avoidance task. Our data show that CBD is able to attenuate motor and cognitive impairments induced by reserpine, suggesting the use of this compound in the pharmacotherapy of Parkinson's disease and tardive dyskinesia.

Novel multifunctional dopamine D2/D3 receptors agonists with potential neuroprotection and anti-alpha synuclein protein aggregation properties

Our ongoing drug development endeavor to design compounds for symptomatic and neuroprotective treatment of Parkinson's disease (PD) led us to carry out a structure activity relationship study based on dopamine agonists pramipexole and 5-OHDPAT. Our goal was to incorporate structural elements in these agonists in a way to preserve their agonist activity while producing inhibitory activity against aggregation of α-synuclein protein. In our design we appended various catechol and related phenol derivatives to the parent agonists via different linker lengths. Structural optimization led to development of several potent agonists among which (-)-8a, (-)-14 and (-)-20 exhibited potent neuroprotective properties in a cellular PD model involving neurotoxin 6-OHDA. The lead compounds (-)-8a and (-)-14 were able to modulate aggregation of α-synuclein protein efficiently. Finally, in an in vivo PD animal model, compound (-)-8a exhibited efficacious anti-parkinsonian effect.

Breathing in Parkinsonism in the Rat

Parkinsonism is underlain by dopamine (DA) deficiency in the mid-brain, a neurotransmitter innately involved with respiratory regulation. However, the state of respiration in parkinsonism is an unsettled issue. In this study we seek to determine ventilation and its responses to hypoxia in a reserpine--alpha-methyl-tyrosine model of parkinsonism in the rat. We also attempted to differentiate between the role of discrete brain and carotid body DA stores in the modulation of the hypoxic ventilatory response (HVR). To this end we used domperidone, a peripheral D2 receptor antagonist, and levodopa, a central D2 receptor agonist. The HVRs to acute 12% and 8% hypoxia were studied in a whole body plethysmograph in the same rats before and after the induction of parkinsonic symptoms in conscious rats. We found that resting ventilation and the HVR were distinctly reduced in parkinsonism. The reduction was particularly evident in the peak hypoxic hyperpneic augmentation. Domperidone, which enhanced ventilation in the control healthy condition, failed to reverse the reduced parkinsonic HVR. In contrast, levodopa, which did not appreciably affected ventilation in the healthy condition, caused the parkinsonic HVR to return to and above the baseline healthy level. The findings demonstrate the predominance of a lack of the central DA stimulatory element and minimize the role of carotid body DA in the ventilatory impediment of parkinsonism. In conclusion, the study provides the pathophysiological savvy concerning the respiratory insufficiency of parkinsonism, a sequela which carries a risk of chronically impaired blood oxygenation, which may drive the disease worsening.

Genetic evidence for chromosome 4 loci influencing learning and memory

The Lewis (LEW) and SHR (Spontaneously Hypertensive Rats) inbred rat strains differ in several anxiety/emotionality and learning/memory-related behaviors. We aimed to search quantitative trait locus (QTL) that influence these behaviors and confirm their effects in a congenic rat strain SLA16 (SHR.LEW.Anxrr16). LEW females and SHR males were intercrossed to produce F2 rats (96/sex), which were all tested in the plus-maze discriminative avoidance task (PMDAT), open-field (OF), object recognition (OR), spontaneous alternation (SA) and fear conditioning (FC). All animals were genotyped for microsatellite markers located on chromosome (Chr) 4. Behavioral and genotypic data were used to perform factor and QTL analyses. Also, to confirm the QTL effects, we tested male and female SLA16 rats and their isogenic control SHR in the same behavioral tests. A factor analysis of the F2 population revealed a correlation between anxiety/emotionality related behaviors and learning/memory in both sexes. QTL analysis revealed two significant QTL in males and three in females, on behavioral parameters in the PMDAT, OF and FC. Four QTL found herein were confirmed in SLA16 rats. The SLA16 strain displayed lower levels of anxiety/emotionality, higher locomotor activity and deficits in learning/memory in comparison with SHR strain. The Chr 4 contains genes influencing anxiety/emotionality and learning/memory behaviors and the SLA16 strain represents a valuable tool in the search for them. The use of the SLA16 strain as a genetic model for studying behavioral phenomena and their implications for psychiatric disorders are discussed.

Nitric oxide pathway activity modulation alters the protective effects of (-)Epigallocatechin-3-gallate on reserpine-induced impairment in rats

Reserpine (RES) has been reported to increase the brain's neural oxidative stress and cause cognitive dysfunction. Having powerful antioxidative properties, green tea catechins, especially (-)epigallocatechin-3-gallate (EGCG), are able to protect against many oxidative injuries. In this study, we examined the protecting properties of EGCG on RES-induced impairment of short-term memory in three-month-old male Wistar rats. RES (1mg/kg i.p.) induced memory impairment (p<0.001) as evaluated by the social recognition task. EGCG treatment (100mg/kg i.p. for 7days, starting 6days before RES injection) was able to improve the impaired memory caused by RES. RES treatment increased the nitric oxide (NO) level and lipid peroxidation (LPO) production, and decreased the antioxidation power in hippocampi. EGCG treatment was able to counteract the RES-induced NO level and LPO production, as well as enhanced the hippocampal antioxidation power in RES-treated rats. In order to examine the implication of NO pathway activity in RES treatment, either NO precursor (L-arginine; L-A) or NO synthase inhibitor (L-NAME; L-N) was co-pretreated with EGCG; NO precursor treatment eliminated the protective effect of EGCG, in contrast to that NO synthase inhibitor treatment significantly increased the EGCG effects on cognitive and biochemical protection in RES-treated rats. These results suggested that the NO pathway was implicated, at least in part, in the RES-induced impairment, as well as in the protective effect of EGCG in treating RES-induced impairment of memory. The above evidence provides a clinically relevant value for EGCG in preventing RES-induced cognitive dysfunction.

Behavioral and neurochemical effects induced by reserpine in mice

RATIONALE

Reserpine, a monoamine-depleting agent, which irreversibly and non-selectively blocks the vesicular monoamine transporter, has been used as an animal model to study several neurological disorders, including tardive dyskinesia and Parkinson's disease.

OBJECTIVE

The purpose of this study was to examine if motor deficits induced by reserpine in mice could be related to alterations in the expression of dopaminergic system proteins such as tyrosine hydroxylase (TH) and dopamine transporter (DAT) and in the activity of monoamine oxidase (MAO).

METHODS

Mice received either vehicle or reserpine (0.1, 0.5, or 1 mg/kg, s.c.) for four consecutive days. Two, 20, or 60 days after reserpine withdrawal, behavioral, and neurochemical changes were evaluated.

RESULTS

Reserpine at a dose of 0.5 and 1 mg/kg increased vacuous chewing movements (VCMs) and reduced locomotion. Behavioral changes were accompanied by reduction in TH immunoreactivity in the striatum evaluated on days 2 and 20 after the last injection of 1 mg/kg reserpine. Furthermore, negative correlations were found between VCM and MAO-A or MAO-B on day 2 and TH striatal immunoreactivity on day 20 after the last injection of 1 mg/kg reserpine. A positive correlation was observed between VCMs and DAT immunoreactivity in the substantia nigra on day 2 after the last injection of 0.5 mg/kg reserpine.

CONCLUSIONS

These findings suggest that the pharmacological blockage of vesicular monoamine transporter (VMAT) by reserpine caused neurochemical and behavioral alterations in mice.

Drugs of abuse and Parkinson's disease

The term "drug of abuse" is highly contextual. What constitutes a drug of abuse for one population of patients does not for another. It is therefore important to examine the needs of the patient population to properly assess the status of drugs of abuse. The focus of this article is on the bidirectional relationship between patients and drug abuse. In this paper we will introduce the dopaminergic systems of the brain in Parkinson's and the influence of antiparkinsonian drugs upon them before discussing this synergy of condition and medication as fertile ground for drug abuse. We will then examine the relationship between drugs of abuse and Parkinson's, both beneficial and deleterious. In summary we will draw the different strands together and speculate on the future merit of current drugs of abuse as treatments for Parkinson's disease.

Polymorphism in the Vesicular Monoamine Transporter 2 Gene Decreases the Risk of Parkinson's Disease in Han Chinese Men

Background. Polymorphisms rs363371 and rs363324 in the vesicular monoamine transporter 2 (VMAT2) gene have been associated with risk of PD in an Italian population, and our aim is to investigate the association between the two single-nucleotide polymorphisms and PD in Han Chinese. Methods. 561 Han Chinese PD patients and 491 healthy age- and gender-matched controls were genotyped using Ligase detection reaction (LDR) method. Result. Both of patient and control groups showed similar genotype frequencies between patients and controls at both rs363371 and rs363324, as well as similar minor A allele frequencies at rs363371 (P = 0.452) and rs363324 (P = 0.413). None of the observed haplotypes showed a significant association with PD. Subgroup analysis by gender and age at onset revealed a significant association between the A allele of rs363371 and PD in Han Chinese males relative to healthy controls (OR 0.799, 95%  CI 0.665 to 0.959, P = 0.016), and this association remained significant after adjusting for age (OR 0.785, 95%  CI 0.652 to 0.945, P = 0.011). Conclusion. These results suggest that polymorphism of VMAT2 locus is associated with risk of PD in Han Chinese overall but that the A allele at rs363371 may protect against PD in Han Chinese males.

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.

(-) 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.

Antidepressant-like effect of tetrahydroisoquinoline amines in the animal model of depressive disorder induced by repeated administration of a low dose of reserpine: behavioral and neurochemical studies in the rat

Animal models are widely used to study antidepressant-like effect in rodents. However, it should be mentioned that pharmacological models do not always take into account the complexity of the disease process. In the present paper, we demonstrated that repeated but not acute treatment with a low dose of reserpine (0.2 mg/kg i.p.) led to a pharmacological model of depression which was based on its inhibitory effect on the vesicular monoamine transporter 2, and monoamines depleting action in the brain. In fact, we observed that chronic treatment with a low dose of reserpine induced a distinct depressive-like behavior in the forced swim test (FST), and additionally, it produced a significant decrease in the level of dopamine, noradrenaline, and serotonin in the brain structures. 1,2,3,4-Tetrahydroisoquinoline (TIQ) and its close methyl derivative, 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) are exo/endogenous amines present naturally in the mammalian brain which demonstrated a significant antidepressant-like effect in the FST and the reserpine model of depression in the rat. Both compounds, TIQ and 1MeTIQ, administered chronically in a dose of 25 mg/kg (i.p.) together with reserpine completely antagonized reserpine-produced depression as assessed by the immobility time and swimming time. Biochemical data were in agreement with behavioral experiments and demonstrated that chronic treatment with a low dose of reserpine in contrast to acute administration produced a significant depression of monoamines in the brain structures and impaired their metabolism. These neurochemical effects obtained after repeated reserpine (0.2 mg/kg i.p.) in the brain structures were completely antagonized by joint TIQ or 1MeTIQ (25 mg/kg i.p.) administration with chronic reserpine. A possible molecular mechanism of action of TIQ and 1MeTIQ responsible for their antidepressant action is discussed. On the basis of the presented behavioral and biochemical studies, we suggest that both compounds may be effective for the therapy of depression in clinic as new antidepressants which, when administered peripherally easily penetrate the blood–brain barrier, and as endogenous compounds may not have adverse side effects.

Revealing interaction between sulfobutylether-β-cyclodextrin and reserpine by chemiluminescence and site-directed molecular docking

The host-guest interaction between sulfobutylether-β-cyclodextrin (SBE-β-CD) and reserpine (RSP) is described using flow injection-chemiluminescence (FI-CL) and site-directed molecular docking methods. It was found that RSP could inhibit the CL intensity produced by a luminol/SBE-β-CD system. The decrease in CL intensity was logarithmic over an RSP concentration range of 0.03 to 700.0 nM, giving a regression equation of ∆I = 107.1lgCRES  + 186.1 with a detection limit of 10 pM (3σ). The CL assay was successfully applied in the determination of RSP in injection, saliva and urine samples with recoveries in the range 93.5-106.1%. Using the proposed CL model, the binding constant (KCD-R ) and the stoichiometric ratio of SBE-β-CD/RSP were calculated to be 7.4 × 10(6)  M(-1) and 1 : 1, respectively. Using molecular docking, it was confirmed that luminol binds to the small cavity of SBE-β-CD with a nonpolar interaction, while RSP targeted the larger cavity of SBE-β-CD and formed a 1 : 1 complex with hydrogen bonds. The proposed new CL method has the potential to become a powerful tool for revealing the host-guest interaction between CDs and drugs, as well as monitoring drugs with high sensitivity.

Protective effect of nebivolol on reserpine-induced neurobehavioral and biochemical alterations in rats

Reserpine-induced orofacial dyskinesia is a model that shares some mechanists' aspects with tardive dyskinesia whose pathophysiology has been related to oxidative stress. The present study was aimed to explore neuroprotective effects of nebivolol, an antihypertensive agent, on reserpine-induced neurobehavioral and biochemical alterations in rats. Reserpine (1mg/kg, s.c.) was used to induce neurotoxicity. Administration of reserpine for 3 days every other day significantly increased the vacuous chewing movements (VCMs), tongue protrusions (TPs) and reduced the locomotor activity in rats. Pre-treatment with nebivolol (5 and 10mg/kg, p.o. for 5 days) showed dose dependant decrease in VCMs and TP induced by reserpine. Nebivolol also showed significant improvement in locomotor activity. Reserpine significantly increased lipid peroxidation and reduced the levels of defensive antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD) and reduced glutathione (GSH) in rat brain. Nebivolol reversed these effects of reserpine on oxidative stress indices; indicating amelioration of oxidative stress in rat brains. The results of the present study indicated that nebivolol has a protective role against reserpine-induced orofacial dyskinesia. Thus, the use of nebivolol as a therapeutic agent for the treatment of tardive dyskinesia may be considered.

Gallic acid decreases vacuous chewing movements induced by reserpine in rats

Involuntary oral movements are present in several diseases and pharmacological conditions; however, their etiology and efficient treatments remain unclear. Gallic acid is a natural polyphenolic acid found in gall nuts, sumac, oak bark, tea leaves, grapes and wine, with potent antioxidant and antiapoptotic activity. Thus, the present study investigated the effects of gallic acid on vacuous chewing movements (VCMs) in an animal model induced by reserpine. Rats received either vehicle or reserpine (1mg/kg/day, s.c.) during three days, followed by treatment with water or different doses of gallic acid (4.5, 13.5 or 40.5mg/kg/day, p.o.) for three more days. As result, reserpine increased the number of VCMs in rats, and this effect was maintained for at least three days after its withdrawal. Gallic acid at two different doses (13.5 and 40.5mg/kg/day) has reduced VCMs in rats previously treated with reserpine. Furthermore, we investigated oxidative stress parameters (DCFH-DA oxidation, TBARS and thiol levels) and Na(+),K(+)-ATPase activity in striatum and cerebral cortex, however, no changes were observed. These findings show that gallic acid may have promissory use in the treatment of involuntary oral movements.

Acute treatment with bis selenide, an organic compound containing the trace element selenium, prevents memory deficits induced by reserpine in rats

Taking into account the promising pharmacological actions of (Z)-2,3-bis(4-chlorophenylselanyl) prop-2-en-1-ol) (bis selenide), an organic compound containing the trace element selenium, and the constant search for drugs that improve the cognitive performance, the objective of the present study was to investigate whether bis selenide treatment ameliorates memory deficits induced by reserpine in rats. For this aim, male adult rats received a single subcutaneous injection of reserpine (1 mg/kg), a biogenic amine-depleting agent used to induce memory deficit. After 24 h, bis selenide at doses of 25 and 50 mg/kg was administered to rats by intragastric route, and 1 h later, the animals were submitted to behavior tasks. The effects of acute administration of bis selenide on memory were evaluated by social recognition, step-down passive avoidance, and object recognition paradigms. Exploratory and locomotor activities of rats were determined using the open-field test. Analysis of data revealed that the social memory disruption caused by reserpine was reversed by bis selenide at both doses. In addition, bis selenide, at the highest dose, prevented the memory deficit resulting from reserpine administration to rats in step-down passive avoidance and object recognition tasks. No significant alterations in locomotor and exploratory behaviors were found in animals treated with reserpine and/or bis selenide. Results obtained from distinct memory behavioral paradigms revealed that an acute treatment with bis selenide attenuated memory deficits induced by reserpine in rats.