HYPOTHALAMIC MONOAMINE LEVELS DURING EARLY AND LATE POSTNATAL PERIODSIN MALE AND FEMALE RATS

Physiological and biochemical variations in neurotransmitter (NT) syst ems might be correlated with brain functional and structural sex diffe rences. To determine the physiological significance of this correlatio n, we measured the hypothalamic levels of serotonin (5HT) and its meta bolite 5-hydroxyindolacetic acid (5HIAA), dopamine (DA) and norepineph rine (NE) by radioenzymatic methods in male and female rats during ear ly (1-5 days) and late (7-25 days) postnatal periods. Results showed: (a) Differences in NT levels during both postnatal periods, (b) Change s in an opposite direction between NE and DA levels and (c) A clear se x difference in 5HT levels, particularly on day 10. These data suggest that monoaminergic metabolism may be an important factor contributing to hormonal and environmental-induced changes (morphological and beha vioural), that occur during brain sexual differentiation.