Adolescent exposure to nicotine and/or the cannabinoid agonist CP 55,940 induces gender-dependent long lasting memory impairments and changes in brain nicotinic and CB1 cannabinoid receptors

We have analysed the long-term effects of adolescent (postnatal day 28-43) exposure of male and female rats to nicotine (NIC, 1.4 mg/kg/day) and/or the cannabinoid agonist CP 55,940 (CP, 0.4 mg/kg/day) on the following parameters measured in the adulthood: (1) the memory ability evaluated in the object location task (OL) and in the novel object test (NOT); (2) the anxiety-like behaviour in the elevated plus maze; and (3) nicotinic and CBI cannabinoid receptors in cingulated cortex and hippocampus. In the OL, all pharmacological treatments induced significant decreases in the DI of females, whereas no significant effects were found among males. In the NOT, NIC-treated females showed a significantly reduced DI, whereas the effect of the cannabinoid agonist (a decrease in the DI) was only significant in males. The anxiety-related behaviour was not changed by any drug. Both, nicotine and cannabinoid treatments induced a long-lasting increase in CBI receptor activity (CP-stimulated GTP gamma S binding) in male rats, and the nicotine treatment also induced a decrease in nicotinic receptor density in the prefrontal cortex of females. The results show gender-dependent harmful effects of both drugs and long-lasting changes in CBI and nicotinic receptors.