Role of 5-HT7 receptors in the anxiety-like behavior in naloxone-induced withdrawal symptoms in mice

Pharmacological studies have implicated anxiety behavior in the withdrawal of opiates. There is evidence demonstrating the role of serotonergic system and recently the role of 5-HT7 receptor regulation has been shown in anxiety behavior. The aim of the present study was to evaluate the effects of 5-HT7 receptor agonists and antagonists on anxiety behavior related to morphine withdrawal in male mice. Morphine dependence was induced by repeated treatment with morphine within 5 consecutive days. The anxiety responses were measured after the last morphine administration. Morphine-dependent mice were pretreated with AS19 (3 and 10 mg/kg, i.p.), SB269970 (1 and 10 mg/kg, i.p.) or saline, and subsequently with naloxone (3 mg/kg, s.c), prior to testing in elevated plus-maze. The number of entries into the open arms and the time spent in the open arms were measured. The results showed that there were no significant differences in the number of entries into the open arms and the time spent in open areas of plus-maze between the experimental groups. It was concluded that neither SB269970 nor AS19 had any effect on anxiety behavior related to morphine. The 5-HT7 receptor had no significant role in the anxiety behavior related to morphine withdrawal.