| Abstract |
Marijuana is the most commonly used illegal substance in the world, with adolescents being particularly vulnerable to its use and abuse. According to research findings, chronic exposure to cannabis and synthetic cannabinoids during adolescence increases the risk of using other addictive substances in adulthood. The purpose of the present study is to determine the effects of chronic administration of the cannabinoid receptor agonist WIN 55, 212-2 during adolescence and adulthood on the reward-facilitating effects of cocaine in adult rats. For this purpose, male Sprague-Dawley rats were divided into two groups and received chronic WIN 55, 212-2 (0, 0.1, 1 mg/kg, i.p.) injections, one group in adolescence (postnatal day 30-51) and the other in adulthood (postnatal day 65-86). Rats were then assessed for potential alterations of cocaine’s (0, 2.5, & 10mg/kg, i.p.) reward-facilitating effects by using the curve-shift variant of the intracranial self-stimulation (ICSS) procedure. The results of the present study show that rats that were exposed to the 1 mg/kg WIN 55,212-2 dose in adolescence showed an increase in ICSS threshold compared to the control group and the group that was received the 0.1 mg/kg dose of WIN 55,212-2. Moreover 1 mg/kg of WIN 55,212-2 produced a decrease of the asymptotic rate of responding compared to the control group both in adolescence and adulthood during ICSS acquisition. Administration of cocaine (0, 2.5, and 10 mg / kg, i.p.) to drug-naïve rats caused a dose-dependent decrease of ICSS threshold in both experimental groups. Furthermore, 2.5 mg of cocaine produced a significantly greater decrease in ICSS threshold of rats that were exposed to 1 mg/kg WIN 55,212-2 in both adolescence (greater) and adulthood (minor) compared to the control group. The dose of 10 mg/kg of cocaine slightly decreased ICSS threshold of rats that were exposed to 1 mg/kg WIN 55,212-2 in both adolescence and adulthood compared to the control group, but this effect was not statistically significant. Overall, the present results reveal that chronic cannabinoid exposure can affect (increase) the reward-facilitating effects of other addictive substances, such as cocaine, which may explain some cases where cannabis is a gateway drug for other, more harmful, addictive substances.
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Οι επιδράσεις της χρόνιας χορήγησης κανναβινοειδών σε επίμυς κατά την εφηβεία και την ενήλικη ζωή, στις ενισχυτικές δράσεις της κοκαΐνης στον ενήλικο επίμυ
