CHANGES IN HYPOTHALAMIC NORADRENALINE, DOPAMINE AND SEROTONIN UPTAKE AFTER OESTRADIOL ADMINISTRATION TO RATS

Abstract Instituto Latinoamericano de Fisiología de la Reproducción (ILAFIR), CC10, San Miguel 1663, PBA, Argentina (Received 1 September 1976) Ever since the initial observations demonstrating the importance of central monoaminergic mechanisms in the control of ovulation (Sawyer, Markee & Townsend, 1949) evidence has accumulated that gonadotrophin and prolactin secretion and sexual behaviour can be changed by altering monoamine receptor activity in the brain, particularly in the hypothalamus. It has also become apparent that the central effects of sex steroids can be partly explained via changing activity of central monoaminergic neurones. A variety of transport mechanisms for their respective neurotransmitters have been described in peripheral and central neurones and considerable evidence indicates that the removal of the released transmitter from the synaptic cleft constitutes a major mechanism to terminate neurotransmission (Iversen, 1971). High concentrations (10−4 to 10−5 mol/l) of oestradiol and progesterone added in vitro have been found to decrease noradrenaline, dopamine