Effect of hypothalamic deafferentation on hypophysial and other endocrine gland blood flows

The effects of partial or complete deafferentation of the medical basal hypothalamus (MBH) on blood flow through endocrine glands was evaluated using a modification of Sapirstein's indicator fractionation method. Adult female Wistar rats were distributed into three groups consisting of normal control animals (n = 12), animals in which rostral deafferentation (Rd) of the MBH was performed (n = 11), and animals in which complete deafferentation (Cd) of the MBH was done (n = 6). Three weeks after the surgical procedures, Cd reduced adenohypophysial weight by 30% and raised its blood flow levels by 80% compared to those values in the Rd and control groups. In contrast to the anterior pituitary, both Rd and Cd led to weight reduction of 22% in posterior lobes, and Cd was also accompanied by a 50% net blood flow decrease. No statistically significant differences were noted in pineal gland weights or decreases in blood perfusion rates in adrenal and thyroid glands. There were no body weight changes in experimental animals compared to values in the control groups. These results suggest that there may be a loss of vasomotor tone in the primary vascular beds of the adenohypophysial portal systems after deafferentation which elicits the 80% increase in adenohypophysial blood flow. This increased circulation may play a role in pituitary function(s) and should be included along with diminished neuroendocrine inputs in interpretations of results obtained after deafferentation procedures.