Distribution of oxytocic and vasopressor activity in the rat diencephalon

Abstract

The oxytocic and vasopressor activity was studied in five 1 mm thick, horizontal sections of the rat diencephalon. The diencephalon was cut frozen in dry ice. The sections obtained from identical parts of the diencephalon of 10 rats were homogenized together in 0.9% NaCl solution acidified with glacial acetic acid. The homogenate was heated to 100 degrees C for 5 min and centrifuged. The oxytocic activity of extracts was determined in vitro by, the method of Holton using the rat myometrium. The vasopressor activity was determined in vivo recording blood pressure in the carotid artery of rat by the method of Dekańaski. Oxytocic activity was found in all five sections of diencephalon and vasopressor activity in only two sections. The first section included the median eminence and ventral hypothalamus together with the supraoptic nucleus, the second section included the the dorsal hypothalamus with paraventricular nucleus, the third section--the ventral thalamus, the fourth section--the middle part of thalamus, the fifth section--the dorsal thalamus.