Effects of 8-OH-DPAT on open field performance of young and aged rats prenatally exposed to diazepam: a tool to rveal 5-HT1a receptor function

Central GABAergic and serotoninergic systems interact with one another and are implicated in controlling different behaviours. Agentle early long-lasting handling can prevent the deficits in locomotion and exploration in open field (O.F.) in 3-month-old male ratsprenatally exposed to diazepam (DZ). Purpose of this study was to extend the research to older handled rats prenatally exposed to DZ andto assess the activity of 5-HT1A receptors (Rs), evaluating the performance in O.F. at 3 and 18 months of age following 8-OH-DPATadministration. A single daily s.c. injection of DZ (1.5 mg/kg) from gestation day 14 to gestation day 20 induced in aged, but not inyoung rats, a decrease in total distance travelled (TDT) and in rearing frequency (RF) and an increase of transitions from the periphery tothe centre of the arena (CNT) and in the time spent in the centre of the arena (CAT), compared to controls. 8-OH-DPAT (0.150 mg/kgs.c.), given 1 h before testing, increased TDT and decreased RF, CNT and CAT in both vehicle- and DZ-exposed young rats. In aged ratsprenatally exposed to DZ, 8-OH-DPAT induced an increase in TDT and a slight decrease in RF, CNT and CAT. These findings indicatethat the effects of handling and of 8-OH-DPAT in prenatally DZ-exposed rats are age-dependent and suggest that O.F. test can represent avalid tool to identify the changes in 5-HT1A Rs activity following drug treatment