Intraventricular administration of vasopressin and oxytocin effects the steady-state levels of serotonin, dopamine and norepinephrine in rat brain.

The effect of lysine-8-vasopressin (LVP) and oxytocin (OXT) has been studied on the steady-state level of serotonin (5-HT),dopamine(DA) and norepinephrine (NE) in various brain areas four hours after intraventricular microinjection of the neuropeptides. LVP (50 microU) diminished in content of 5-HT and NE in the mesencephalon, the content of 5-HT in the septum as well as the content of DA and NE in the dorsal hippocampus. OXT (500 microU), on the other hand, decreased the content of 5-HT, DA and Ne in the hypothalamus, as well as the content of DA in the mesencephalon. In contrast, the septal NW level was increased following OXT treatment. The data indicate that both LVP and OXT are capable of influencing the 5-HT and catecholamine levels as late as 4 h after their administration. Therefore, our findings support the previous notion that posterior pituitary neuropeptides affect behavioral processes via interacting with the cerebral monoaminergic neurotransmission.