Mirtazapine attenuates the expression of nicotine-induced locomotor sensitization in rats

Mirtazapine decreased cocaine-induced c-fos expression and dopamine release in rats

Introduction

Chronic cocaine exposure induces an increase in dopamine release and an increase in the expression of the Fos protein in the rat striatum. It has been suggested that both are necessary for the expression of cocaine-induced alterations in behavior and neural circuitry. Mirtazapine dosing attenuated the cocaine-induced psychomotor and reinforcer effects.

Methods

The study evaluates the effect of chronic dosing of mirtazapine on cocaine-induced extracellular dopamine levels and Fos protein expression in rats. Male Wistar rats received cocaine (10 mg/Kg; i.p.) during the induction and expression of locomotor sensitization. The mirtazapine (30 mg/Kg; MIR), was administered 30 minutes before cocaine during the cocaine withdrawal. After each treatment, the locomotor activity was recorded for 30 minutes. Animals were sacrificed after treatment administration. Dopamine levels were determined by high-performance liquid chromatographic (HPLC) in the ventral striatum, the prefrontal cortex (PFC), and the ventral tegmental area (VTA) in animals treated with mirtazapine and cocaine. The quantification of c-fos immunoreactive cells was carried out by stereology analysis.

Results

Mirtazapine generated a decrease in cocaine-induced locomotor activity. In addition, mirtazapine decreased the amount of cocaine-induced dopamine and the number of cells immunoreactive to the Fos protein in the striatum, PFC, and VTA.

Discussion

These data suggest that mirtazapine could prevent the consolidation of changes in behavior and the cocaine-induced reorganization of neuronal circuits. It would explain the mirtazapine-induced effects on cocaine behavioral sensitization. Thus, these data together could support its possible use for the treatment of patients with cocaine use disorder.

Evaluation of multitarget drugs on the expression of cocaine-induced locomotor sensitization in male rats: A comparative study

Purpose

- Cocaine use disorder (CUD) is a complex disease. Several studies have shown the efficacy of multitarget drugs used to treat CUD. Here we compare the efficacy of mirtazapine (MIR), pindolol (PIN), fluoxetine (FLX), risperidone (RIS), trazodone (TRZ), ziprasidone (ZPR), ondansetron (OND), yohimbine (YOH), or prazosin (PRZ), to reduce long-term cocaine-induced locomotor activity and the expression of cocaine-induced locomotor sensitization in rats.

Methods

- The study consists of four experiments, which were divided into four experimental phases. Induction (10 days), cocaine withdrawal (30 days), expression (10 days), and post-expression phase (10 days). Male Wistar rats were daily dosed with cocaine (10 mg/kg; i.p.) during the induction and post-expression phases. During drug withdrawal, the MIR, PIN, FLX, RIS, TRZ, ZPR, OND, YOH, or PRZ were administered 30 min before saline. In the expression, the multitarget drugs were administered 30 min before cocaine. After each administration, locomotor activity for each animal was recorded for 30 min.During the agonism phase, in experiment four, 8-OH-DPAT, DOI, CP-809-101, SR-57227A, or clonidine (CLO) was administered 30 min before MIR and 60 min before cocaine. After each administration, locomotor activity for each animal was recorded for 30 min.

Results

-MIR, FLX, RIS, ZPR, OND, or PRZ attenuated the cocaine-induced locomotor activity and cocaine locomotor sensitization. PIN, TRZ, and YOH failed to decrease cocaine locomotor sensitization. At the optimal doses used, PIN, FLX, RIS, TRZ, ZPR, OND, YOH, or PRZ failed to attenuate long-term cocaine locomotor activation. MIR generated a decrease in cocaine-induced locomotor activity of greater magnitude and duration than the other multitarget drugs evaluated.

Conclusion

- At the optimal doses of multitarget drugs evaluated, MIR was the multitarget drug that showed the greatest long-term cocaine-induced behavior effects compared to other multitarget drugs.

Mirtazapine attenuates the cocaine-induced locomotor sensitization in male and female C57BL/6J and BALBA/cJ mouse

BACKGROUND

Clinical studies have described the efficacy of various therapeutic approaches. Results are inconsistent and clinical application is limited. Clinical trials have suggested that individual variability in the response to pharmacological therapies and sex affects the efficacy of some antidepressant drugs. Mouse strain-dependent variability influenced the response to antidepressant drugs. Some mouse strains respond faster and better to antidepressants than other mouse strains. We recently reported a series of preclinical studies that showed that dosing of mirtazapine, a noradrenergic and serotonergic antidepressant, in male and female Wistar rats decreased cocaine-induced locomotor activity and attenuated the induction and expression of cocaine-induced locomotor sensitization. Therefore, the aim of this study was to evaluate the mirtazapine effects, on cocaine-induced locomotor activity and cocaine-induced locomotor sensitization in male and female mice of the C57BL/6J and BALB/cJ strains, which differ in sensitivity to the cocaine motor effects and response to antidepressant drugs.

METHODS

Male and female BALB/cJ and C57BL/6J inbred mice (20-25 g) were daily dosed with 10 mg/kg of cocaine during the induction and expression of locomotor sensitization. During drug withdrawal, cocaine was withdrawn, and the groups received daily mirtazapine (30 mg/kg, i.p.) or saline. Mirtazapine was administered 30 min before cocaine. After each administration, locomotor activity for each animal was recorded for 30 min in transparent Plexiglass activity chambers.

RESULTS

Cocaine-induced locomotor activity were greater in C57BL/6J strain mice than BALB/cJ strain mice during the induction and expression phase of locomotor sensitization. The female mice of both strains showed a higher cocaine locomotor response than males and mirtazapine significantly decreased cocaine-induced locomotor activity, as well as the induction and expression of locomotor sensitization, regardless of mouse strain or sex.

CONCLUSION

The results suggest mirtazapine may be considered an effective therapeutic option to treat cocaine use disorder in men and women with very diverse genetic backgrounds.

Prenatal and Postnatal Cocaine Enhances the Induction and Expression of Locomotor Sensitization to Nicotine in Male Rats

INTRODUCTION

Several studies mention that early consumption of cannabis, alcohol, or even cocaine is related to an increase in the prevalence of daily consumption of tobacco in adulthood. However, other factors, such as genetic comorbidity, social influences, and even molecular, neurochemical, and behavioral alterations induced by prenatal and postnatal cocaine exposure, could also explain these observations, since these factors together increase the vulnerability of the offspring to the reinforcing effects of nicotine. The objective of this study was to determine the effect of prenatal and postnatal exposure to cocaine on nicotine-induced locomotor sensitization in young and adult rats.

AIMS AND METHODS

The study was divided into two stages: prenatal and postnatal. In the prenatal stage, a group of pregnant female Wistar rats was administered cocaine daily from day GD0 to GD21 (cocaine preexposure group), and another group of pregnant female rats was administered saline daily (saline preexposure group). Of the litters resulting from the cocaine preexposed and saline preexposed pregnant female groups, in the postnatal stage, only the male rats were used for the recording of the locomotor activity induced by different doses of nicotine (0.2, 0.4, and 0.6 mg/kg) during the induction and expression of locomotor sensitization at different postnatal ages (30, 60, 90, and 120 days).

RESULTS

Prenatal and postnatal cocaine exposure enhanced nicotine-induced locomotor activity and locomotor sensitization.

CONCLUSIONS

This suggests that prenatal and postnatal cocaine exposure can result in increased vulnerability to other drugs of abuse, such as nicotine, in humans.

IMPLICATIONS

Several studies have shown that the abuse of a drug, such as cannabis, alcohol, or even cocaine, at an early age can progress to more severe levels of use of other drugs, such as nicotine, to adulthood. Our data are consistent with this hypothesis, since prenatal and postnatal cocaine exposure enhanced the nicotine-induced increase in locomotor activity and locomotor sensitization. This suggests that prenatal and postnatal exposure to cocaine enhances the drug's salience.

Challenge exposure to whole cigarette smoke condensate upregulates locomotor sensitization by stimulating α4β2 nicotinic acetylcholine receptors in the nucleus accumbens of rats

Nicotine, the primary addictive substance in tobacco, produces the psychomotor, rewarding, and reinforcing effects of tobacco dependence by stimulating nicotinic acetylcholine receptors (nAChRs) in the brain. The present study determined that α4β2 nAChRs regulate locomotor sensitization by altering dopamine concentration in the nucleus accumbens (NAc) after systemic challenge exposure to whole cigarette smoke condensate (WCSC). Rats were administered subcutaneous injection of WCSC (0.2 mg/kg nicotine/day) for 7 consecutive days and then re-exposed to WCSC after 3 days of withdrawal. Challenge exposure to WCSC significantly increased locomotor activity. This increase was decreased by the subcutaneous injection of the α4β2 nAChR antagonist, DHβE (3 mg/kg), but not by the intraperitoneal injection of the α7 nAChR antagonist, MLA (5 mg/kg). In parallel with a decrease in locomotor activity, blockade of α4β2 nAChRs with DHβE decreased dopamine concentration in the NAc which was elevated by challenge exposure to WCSC. These findings suggest that challenge WCSC leads to the expression of locomotor sensitization by elevating dopamine concentration via stimulation of α4β2 nAChRs expressed in neurons of the NAc in rats.

Mirtazapine-induced decrease in cocaine sensitization is enhanced by environmental enrichment in rats

Several studies have reported that mirtazapine attenuated the induction and expression of cocaine-induced locomotor sensitization. Animals placed in enriched housing environments have shown a decrease in cocaine-induced locomotor activity and sensitization. In addition, it has been suggested that a pharmacological treatment combined with a behavioral intervention increases the efficacy of the former. Thus, the objective of this study was to determine if dosing of mirtazapine in an enriched housing environment enhanced the mirtazapine-induced decrease on the induction and expression of cocaine-induced locomotor sensitization. Wistar male rats were dosed with cocaine (10 mg/kg, i.p.). During the drug-withdrawal phase, mirtazapine (30 mg/kg, i.p.) was administered under standard and enriched housing environmental conditions. The environmental enrichment consisted of housing the animals in enclosures with plastic toys, tunnels, and running wheels. After each administration, locomotor activity for each animal was recorded for 30 min. The study found that treatment with mirtazapine in an enriched housing environment produced an enhanced and persistent attenuation of the induction and expression of cocaine-induced locomotor sensitization. Additionally, it reduced the duration of cocaine-induced locomotor activity in the expression phase of locomotor sensitization. Dosing of mirtazapine in an enriched housing environment enhanced the effectiveness of mirtazapine to decrease cocaine-induced locomotor sensitization. This suggests the potential use of enriched environments to enhance the effect of mirtazapine.

Mirtazapine decreased induction and expression of cocaine + nicotine-induced locomotor sensitisation in rats

Objectives: Concurrent abuse of cocaine and nicotine is considered a public health problem. To date, no effective therapy has been known to reduce the reinforcing effects of concurrent use of cocaine and nicotine. Mirtazapine, an antagonist of the α₂-adrenoceptor and the 5-HT_2A/C and the 5-HT₃ receptors has proven effective in reducing the cocaine, nicotine and methamphetamine behavioural effects in humans and animals. Our study evaluated the effect of mirtazapine on enhancing locomotor activity during the induction and expression of locomotor sensitisation induced by a cocaine + nicotine mixture.Methods: Wistar rats were dosed with cocaine, nicotine or cocaine + nicotine combination. Mirtazapine (30 mg/kg, i.p.) was administered during the extinction phase.Results: Mirtazapine decreased cocaine + nicotine-induced locomotor activity and induction and expression of locomotor sensitisation. In addition, we found that co-administration of mecamylamine and mirtazapine significantly enhanced the effect of mirtazapine on cocaine + nicotine-induced locomotor activity during induction and expression of behavioural sensitisation.Conclusions: Our results suggest that mirtazapine demonstrated efficacy in decreasing the psycho-stimulant effects of concurrent use of cocaine and nicotine.

Effect of 4-Fluoro-N-(4-Sulfamoylbenzyl) Benzene Sulfonamide on Acquisition and Expression of Nicotine-Induced Behavioral Sensitization and Striatal Adenosine Levels

Introduction

Behavioral sensitization is a phenomenon that develops from intermittent exposure to nicotine and other psychostimulants, which often leads to heightened locomotor activity and then relapse. Sulfonamides that act as carbonic anhydrase inhibitors have a documented role in enhancing dopaminergic tone and normalizing neuroplasticity by stabilizing glutamate release.

Objective

The aim of the current study was to explore synthetic sulfonamides derivative 4-fluoro-N-(4-sulfamoylbenzyl) benzene-sulfonamide (4-FBS) (with documented carbonic anhydrase inhibitory activity) on acquisition and expression of nicotine-induced behavioral sensitization.

Methods

In the acquisition phase, selected 5 groups of mice were exposed to saline or nicotine 0.5mg/kg intraperitoneal (i.p) for 7 consecutive days. Selected 3 groups were administered with 4-FBS 20, 40, and 60 mg/kg p.o. along with nicotine. After 3 days of the drug-free period, ie, day 11, a challenge dose of nicotine was injected to all groups except saline and locomotor activity was recorded for 30 minutes. In the expression phase, mice were exposed to saline and nicotine only 0.5 mg/kg i.p for 7 consecutive days. After 3 days of the drug-free period, ie, day 11, 4-FBS at 20, 40, and 60 mg/kg were administered to the selected groups, one hour after drug a nicotine challenge dose was administered, and locomotion was recorded. At the end of behavioral experiments, all animals were decapitated and the striatum was excised and screened for changes in adenosine levels, using HPLC-UV.

Results

Taken together, our findings showed that 4-FBS in all 3 doses, in both sets of experiments significantly attenuated nicotine-induced behavioral sensitization in mice. Additionally, 4-FBS at 60mg/kg significantly lowered the adenosine level in the striatum.

Conclusion

The behavioral and adenosine modulation is promising, and more receptors level studies are warranted to explore the exact mechanism of action of 4-FBS.

Mirtazapine reduces the expression of cocaine-induced locomotor sensitization in male and female Wistar rats

BACKGROUND

Epidemiological studies have described that women are more vulnerable to the reinforcing effects of cocaine. In animals, the findings are similar: female rats show higher levels of cocaine self-administration and increased cocaine-induced locomotor activity. In contrast, women with depression respond better to treatment with antidepressants, however their therapeutic response to tetracyclic antidepressants is lower. Several studies have shown that mirtazapine-a tetracyclic antidepressant-decreases the behavioral effects of cocaine in male rats. The objective of this study was to evaluate the efficacy of daily dosing of mirtazapine on cocaine-induced locomotor activity and sensitization in naive female rats compared to male rats.

METHODS

Male and female Wistar rats were daily dosed with 10 mg/kg of cocaine. During extinction, cocaine was withdrawn and the groups received daily mirtazapine (30 mg/kg, i.p.) or saline. Tamoxifen was administered during the antagonism phase. After each administration, locomotor activity for each animal was recorded for 30 min in transparent Plexiglass activity chambers.

RESULTS

In this study, a higher cocaine locomotor response was found in females than in males and the mirtazapine was equally effective in decreasing cocaine-induced locomotor activity and the expression of locomotor sensitization in male and female rats. In addition, co-administration of mirtazapine and tamoxifen enhanced the efficacy of mirtazapine in female rats.

CONCLUSION

The results suggest that mirtazapine may be considered an effective therapeutic option for the treatment of cocaine use disorder in men and women.

Prenatal and postnatal cocaine exposure enhances the induction and expression of locomotor sensitization to cocaine in rats

Prenatal and postnatal exposure to cocaine can affect the development and function of the central nervous system in offspring. It also produces changes in cocaine-induced dopamine release and increases cocaine self-administration and cocaine-induced conditioned place preference. Further, prenatal cocaine exposure involves greater risk for development of a substance use disorder in adolescents. Therefore, the objective of this study was to determine the effect of prenatal and postnatal cocaine exposure on locomotor sensitization in rats. A group of pregnant female Wistar rats were administered daily from day GD0 to GD21 with cocaine (cocaine pre-exposure group) and another group pregnant female rats were administered daily with saline (saline pre-exposure group). During lactation (PND0 to PND21) pregnant rats also received cocaine administration or saline, respectively. Of the litters resulting of the cocaine pre-exposed and saline pre-exposed pregnant female groups, only the male rats were used for the recording of the locomotor activity induced by different doses of cocaine (1, 5, 10, 20 and 40 mg/Kg/day) during the induction and expression of locomotor sensitization at different postnatal ages (30, 60, 90 and 120 days), representative of adolescence and adult ages. The study found that prenatal and postnatal cocaine exposure enhanced locomotor activity and locomotor sensitization, and such increase was dose- and age-dependent. This suggests that prenatal and postnatal cocaine exposure can result in increased vulnerability to cocaine abuse in young and adult humans.

Mirtazapine attenuates nicotine-seeking behavior in rats

BACKGROUND

Nicotine is the major psychoactive component of tobacco. A number of pharmacological therapies have been evaluated, with poor results. Given the lack of success of these therapies, several authors have proposed alternative therapeutic strategies. One of these is the use of antidepressant drugs that may have a specific effect on the neural pathways or receptors underlying nicotine addiction. Mirtazapine is an antagonist of α₂ NE receptors (noradrenergic receptor), 5-HT_2A/C and 5-HT₃ receptors and has demonstrated efficacy in reducing behavioral effects induced by drugs of abuse in human and animal models.

AIMS

In this study, we evaluated the effect of chronic dosing of mirtazapine during extinction on the re-acquisition of nicotine-seeking in rodents.

METHODS

We used the nicotine self-administration paradigm to assess the effects of mirtazapine on rats trained to self-administer nicotine under a pharmacological fixed-ratio schedule. Mirtazapine (30 mg/kg, i.p.) was administered during extinction.

RESULTS

In this work, we found that mirtazapine attenuates the re-acquisition of nicotine-seeking responses.

CONCLUSIONS

These results support the use of mirtazapine in clinical controlled trials as a useful therapy that prolongs and increases rates of preventing relapse into nicotine intake in humans.

Cocaine + nicotine mixture enhances induction and expression of behavioral sensitization in rats

BACKGROUND

Psychoactive substance abuse is a health problem worldwide. Has been reported a high prevalence of use of tobacco and cocaine, either separately or in combination. Clinical and animal studies have suggested that the concurrent use of cocaine and nicotine reinforces the potency of one or both drugs and that nicotine may enhance the reinforcing effects of cocaine. Our study evaluated the combined effects of cocaine and nicotine on locomotor activity during the induction and expression phases of locomotor sensitization-a physiological mechanism that plays an important role in establishing some of the defining characteristics of drug abuse.

METHODS

We used Wistar rats which were dosed with cocaine, nicotine or cocaine and nicotine combination and recorded their locomotor activity in different phases of the experiment.

RESULTS

We found that a daily dose of cocaine combined with nicotine enhanced cocaine- and nicotine-induced locomotor activity, as well as induction and expression of locomotor sensitization. Moreover, we found that pretreatment with nicotine enhanced the locomotor sensitization expression.

CONCLUSION

These results suggest that concurrent use of cocaine and nicotine may result in co-abuse of these drugs.

Effects of the antidepressant mirtazapine and zinc on nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors (nAChRs) and zinc are associated with regulation of mood and related disorders. In addition, several antidepressants inhibit muscle and neuronal nAChRs and zinc potentiates inhibitory actions of them. Moreover, mirtazapine (a noradrenergic, serotonergic and histaminergic antidepressant) inhibits muscarinic AChRs and its effects on nAChRs are unknown. Therefore, we studied the modulation of muscle α1β1γd nAChRs expressed in oocytes and native α7-containing nAChRs in hippocampal interneurons by mirtazapine and/or zinc, using voltage-clamp techniques. The currents elicited by ACh in oocytes (at -60 mV) were similarly inhibited by mirtazapine in the absence and presence of 100 μM zinc (IC₅₀ ∼15 μM); however, the ACh-induced currents were stronger inhibited with 20 and 50 μM mirtazapine in the presence of zinc. Furthermore, the potentiation of ACh-induced current by zinc in the presence of 5 μM mirtazapine was 1.48 ± 0.06, and with 50 μM mirtazapine zinc potentiation did not occur. Interestingly, in stratum radiatum interneurons (at -70 mV), 20 μM mirtazapine showed less inhibition of the current elicited by choline (Ch) than at 10 μM (0.81 ± 0.02 and 0.74 ± 0.02 of the Ch-induced current, respectively). Finally, the inhibitory effects of mirtazapine depended on membrane potential: 0.81 ± 0.02 and 0.56 ± 0.05 of the control Ch-induced current at -70 and -20 mV, respectively. These results indicate that mirtazapine interacts with muscle and neuronal nAChRs, possibly into the ion channel; that zinc may increase the sensitivity of nAChRs to mirtazapine; and that mirtazapine decreases the sensitivity of nAChRs to zinc.