[Histochemical and morphometric evidence of the participation of dorsal hippocampal neurons in the antistress effect of melatonin].

The epiphyseal hormone melatonin (0.1 mg/kg) does not influence the functional state of pyramidal neurons in the dorsal hippocamp of intact rats, but decreases the swimming-stress-induced activation of these neurons. Removal of the pineal gland increased the functional activity of neurons in the intact rats and potentiated the stress-induced histochemical and morphometric changes.