EFFECTS OF PRENATAL MORPHINE ON HYPOTHALAMIC METABOLISM OF NEUROTRANSMITTERS AND GONADAL AND ADRENAL ACTIVITIES, DURING THE EARLY POSTNATAL-PERIOD IN THE RAT

It is noteworthy that exposure to opiates during fetal development res ults in permanent changes in adults related to morphological, behavior al and biochemical measures; however little is known concerning the ef fects of such drugs in early postnatal life. We investigated in newbor n rats the effects of prenatal morphine-exposure on both-the hypothala mic metabolism of norepinephrine (NE), serotonin (5 HT) and neuropepti de Y (NPY)-the activity of the hypothalamo-pituitary gonadal and adren al axes. In a previous study performed in newborns of untreated mother s, we reported some sex-dependent changes in the metabolism of NE, 5 H T and NPY in the hypothalamus and an early activation of the gonadosti mulating function and of the corticostimulating one. In control newbor ns from saline-treated mothers, a slight increase in the hypothalamic metabolism of NE (males) and 5 HT (males and females) was observed and it was comparable in both sexes. On the other hand, the hypothalamic content of NPY was unaffected in early postnatal period in newborn mal es as well as in females. These changes observed on hypothalamic metab olisms are temporally correlated with the early postnatal activation o f the corticostimulating function in neonates of both sexes and that o f the gonadostimulating one, mainly in males. Prenatal morphine exposu re altered the hypothalamic metabolism of 5 HT which was increased mai nly in newborn females but did not affect either the metabolism of NE or the NPY content of the hypothalamus. The more drastic effect of the prenatal morphine treatment is the atrophy and hypoactivity of the ad renals in newborns of both sexes at birth time and during the early po stnatal period. Tn contrast morphine did not impair postnatal surge of the plasma testosterone level in male pups as well as late and slight increase of plasma estradiol in female ones.