CHANGES IN HYPOTHALAMIC CALMODULIN CONCENTRATION INDUCED BY PERINATALHORMONE MANIPULATION IN THE RAT

Calmodulin (CaM) presence and concentration was determined (RIA) in th e rat hypothalamus (2, 6, 12, 24 h and 90 days after birth) in vehicle -treated animal (controls), in testosterone propionate (TP)-treated fe males (30 mu g/rat subcutaneously 1 h after birth) and in tamoxifen-tr eated males (200 mu g/rat subcutaneously 1 h after birth). CaM concent ration, either as total content/hypothalamus or as concentration per m g ww, was significantly higher in both male and female adult rats than in newborn subjects. CaM concentration/mg protein increased with age, being two times higher in adult males and greater than three times hi gher in adult females than in their respective newborns. Two, 12, and 24 h after birth CaM concentration was significantly lower in control females than in control males. This relation was reversed in adults in which CaM concentration was higher in females. The application of TP to the females and tamoxifen to the males, induced a significant decre ase in CaM/mg protein, both in the newborn (2 and 6 h) and in the adul t animals. In adults, treated females had CaM concentrations similar t o those found in control males. Our data suggest: first, a lasting eff ect of newborn hormonal treatment upon the CaM concentration in rat hy pothalamus; second, that CaM is preferentially synthesized in the adul t female hypothalamus, indicating an important role of this protein in female reproductive function. (C) 1998 Elsevier Science Inc.