[Functional relationships between the midbrain tegmentum and the supraoptico-hypophyseal neurosecretory system of the...

Bilateral electrolytic destruction of the paramedian midbrain caudal tegmentum caused the appearance in the internal part of the hypothalamic supraoptic nucleus of neurosecretory cells with low functional activity and degenerating forms (dark-stained and pycnomorphic cells); in the posterior hypophysis the destructed gigantic terminal varicosities (Herring bodies) were revealed; the posterior hypophysis contained a subnormal amount of neurosecret; the vasopressin-antidiuretic hormone level in blood plasma was reduced. Painful stimulation of animals with the destructed midbrain tegmentum revealed the functional insufficiency of the supraoptic hypophyseal neurosecretory system (SHNS). The results obtained permit considering that the paramedian midbrain tegmentum exerts a modulating influence upon the SHNS function during stress.