VASOACTIVE INTESTINAL PEPTIDE - LEVELS AND FUNCTIONAL RECEPTORS IN RAT-BRAIN BEFORE AND AFTER WEANING

The average level of VIP was found to be 17 pmol/g wet weight in the brain of the newborn rat. This level ramained constant during the first two weeks after birth then increased progressively to 40 pmol/g wet weight at 20 days, a value comparable to that found in adult animals. VIP was already able to stimulate brain membrane adenylate cyclase activity at birth. The stimulation with 10-6 M VIP allowed a 2.5-fold increase in basal activity in membranes from 1 to 14-days-old pups as compared to a 1.7-fold stimulation in membranes from adult brain. The apparent activation constant for VIP adenylate cyclase stimulation was 4.10-7 M at all ages. The efficiency of VIP activation amounted to as much as 70% of that of fluoride at birth and to 35% only of fluoride activation in brain membranes from adult rats. © 1979.