RESUMO
Fencamfamine (FCF) is a psychostimulant classified as an indirect dopamine agonist. The conditioning place preference (CPP) paradigm was used to investigate the reinforcing properties of FCF. After initial preferences had been determined, animals were conditioned with FCF (1.75, 3.5, or 7.0 mg/kg; IP). Only at the dose of 3.5 mg/kg FCF produced a significant place preference. Pretreatment with SCH23390 (0.05 mg/kg; SC) or naloxone (1.0 mg/kg; SC) 10 min before FCF (3.5 mg/kg, IP) blocked both FCF-induced hyperactivity and CPP. Pretreatment with metoclopramide (10.0 mg/kg; IP) or pimozide (1.0 mg/kg, IP), respectively, 30 min or 4 h before FCF (3.5 mg/kg; IP), which blocked the FCF-induced locomotor activity, failed to influence place conditioning produced by FCF. In conclusion, the present study suggests that dopamine D1 and opioid receptors are related to FCF reinforcing effect, while dopamine D2 subtype receptor was ineffective in modifying FCF-induced CPP.
Assuntos
Estimulantes do Sistema Nervoso Central/farmacologia , Antagonistas dos Receptores de Dopamina D2 , Norbornanos/farmacologia , Receptores de Dopamina D1/antagonistas & inibidores , Receptores Opioides mu/antagonistas & inibidores , Reforço Psicológico , Animais , Benzazepinas/farmacologia , Ligação Competitiva/efeitos dos fármacos , Estimulantes do Sistema Nervoso Central/antagonistas & inibidores , Condicionamento Operante/efeitos dos fármacos , Metoclopramida/farmacologia , Naloxona/farmacologia , Norbornanos/antagonistas & inibidores , Pimozida/farmacologia , Ratos , Receptores de Dopamina D1/agonistas , Receptores de Dopamina D2/agonistas , Receptores Opioides mu/agonistasRESUMO
1. The effects of apomorphine (APO) administration on DA system activity were assessed by measuring dopamine metabolite levels (HVA) in several circumstances. 2. Pretreatment with IMI reduced the effect of APO on HVA levels. 3. Pretreatments with either IDE or DMI did not reduce the effect of APO on HVA levels. 4. Reductions of either NE and 5-HT levels after DSP4 and pCPA restored the effect of APO after IMI pretreatment.
Assuntos
Corpo Estriado/metabolismo , Imipramina/farmacologia , Norepinefrina/fisiologia , Receptores Dopaminérgicos/efeitos dos fármacos , Serotonina/fisiologia , Animais , Apomorfina/farmacologia , Benzilaminas/farmacologia , Corpo Estriado/efeitos dos fármacos , Fenclonina/farmacologia , Ácido Homovanílico/metabolismo , Técnicas In Vitro , Masculino , Norepinefrina/metabolismo , Piperidinas/farmacologia , Ratos , Ratos Endogâmicos , Serotonina/metabolismo , Antagonistas da Serotonina/farmacologiaRESUMO
Fencamfamine (FCF) is a psychostimulant classified as an indirect dopaminergic agonist. Circadian rhythms of some behavioral and neurochemical parameters were investigated in control rats and in rats which had been treated with a single dose of FCF across the 24-hr span. Rats were entrained to light/dark (LD) 12:12, lights on from 0700 to 1900. In behavioral experiments (performed in March) the rats were injected intraperitoneally with saline or FCF (3.5 mg/kg) at one of six times: 0900, 1300, 1700, 2100, 0100 or 0500. Fifteen minutes after treatment the duration of sniffing, rearing and locomotion was recorded during 120 min. Controls showed circadian rhythms for sniffing and rearing with acrophases at 2255 and 0118, respectively. In animals treated with FCF, only locomotion displayed significant circadian variation with acrophase at 1912. Two-way analysis of variance (ANOVA) showed a statistically significant circadian time-dependent effect of FCF on all behavioral parameters studied; the increase of sniffing, rearing and locomotion induced by FCF was higher in rats treated during the rest phase. In the biochemical studies (performed between March-June), rats were treated (i.p.) with saline or FCF (10 mg/kg) at one of four times: 0900, 1700, 2100 or 0100. The levels of homovanillic acid (HVA) in the striatum and tuberculum olfactorium, 5-hydroxyindolacetic acid (5-HIAA) in the cerebellum and 3-methoxy-4-hydroxypheniglycol (MHPG) in the frontal cortex were determined. Controls showed circadian rhythms for HVA (striatum), MHPG (frontal cortex) and 5-HIAA (cerebellum) with acrophases at 2233, 1955 and 1029, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)