Pituitary ACTH Content in Rats After Partial or Total Interruption of Neural Afferents to the Medial Basal Hypothalamus

Abstract

The ACTH content of rat pltultarles was determined 4 weeks after partial or total interruption of neural connections of the medial basal hypothalamus (MBH). Complete deafferentation of the MBH resulted in a marked increase in pituitary ACTH content and a disappearance of the diurnal ACTH rhythm present in the sham-operated controls. Similar findings were obtained after the Interruption of the anterior connections of the MBH, leaving all other afferents intact. The severence of the dorsal, lateral and posterior connections of the MBH did not interfere with pituitary ACTH content, including the diurnal ACTH rhythm. It is concluded that the neural pathways reaching the MBH from anterior are essential for the maintenance of normal ACTH secretion.