Preovulatory injection of estradiol-17β : effect on noradrenaline activity in different parts of the rabbit oviduct

This paper compares noradrenaline content in the different parts of the oviduct in rabbits receiving or not a dose of estradiol-17 beta 24 h before human chorionic gonadotropin (HCG) and killed 60 h post HCG. 3,4-Dihydroxyphenylalanine assays were carried out in the oviduct after aromatic L-amino acid decarboxylase was inhibited by m-hydroxybenzylhydrazine (NSD 1015) in the same experimental conditions. Pauerstein et al. (1974) have shown that an intramuscular injection of 250 micrograms of estradiol-17 beta in rabbits 24 h before intravenous injection of 100 IU of HCG delays ovum transport at the ampullary-isthmic junction. The extent of this noradrenergic innervation suggested that estradiol could act at least partially through the noradrenergic systems. Our results show that estradiol-17 beta increased oviduct weight by water retention without modifying either the tyrosine hydroxylase activity or the noradrenaline content in any part of the oviduct and that, consequently, the estrogen-induced "tube locking" of ova was not mediated through the noradrenergic processes.