Effect of pre- and postnatal nicotine exposure on vasopressinergic system in rats.

Timed pregnant Sprague-Dawley rats were infused subcutaneously either with nicotine (NIC, 6 mg kg-1 day-1; n=17) or saline (control, n=15) on the 3rd day of gestation, via Alzet osmotic pumps, for 28 days. After the parturition, the pups of both, control and NIC infused dams, were each randomly divided into 2 groups and placed to be nursed as following: (1) control dams nursing pups born to control mother (control group); (2) control dams nursing pups born to NIC-infused mother (prenatal NIC group); (3) NIC-infused dams nursing pups born to control mother (postnatal NIC group); (4) NIC-infused dams nursing pups born to NIC-infused mother (pre- and postnatal NIC group). Vasopressin (VP) was measured by RIA in plasma, neurointermediate lobe (NIL) and hypothalamus (HT) in the pups of both sexes, at the following age: 0 (within 24 h after birth); 1, 2, 3, 4 and 6 weeks. At the age of 3, 4 and 6 weeks, the isolated NILs were individually superfused and VP was measured as a basal release and the response to a 10-min 56 mM potassium stimulation. A marked suppression in the activity of VP-ergic system was observed in both sexes of offspring exposed to NIC prenatally, being first detectable at the age of 3 weeks, when the HT-NIL system becomes fully developed. However, the significant changes were observed at the age of 6 weeks: decreased serum VP concentration, lower VP contents in the HT and NIL, and suppressed VP release, basal and stimulated, from the isolated NIL. Postnatal exposure to nicotine was ineffective.