A Role for the Ovaries in Maturational Processes of Hypothalamic Neurons Containing Luteinizing Hormone- Releasing Hormone*

Abstract

The role of the ovaries in the maturation of the hypothalamic LHRH neuron has been investigated. Female rats were castrated at 4 weeks of age, and the subcellular distribution as weLl as the content of LHRH in the hypothalamic homogenates was analyzed 2.5, 12, and 20 weeks after ovariectomy. Hypothalami were homogenized in an isoosmotic sucrose solution, and a 900 X g supernatant fluid was prepared. Free granules and synaptosomes containing LHRH were separated by means of continuous sucrose density gradient centrifugation. In hypothalamic homogenates of intact immature female rats, 35% of the LHRH was associated with free granules and 65% was associated with synaptosomes; in homogenates of adult rats, 57% of the LHRH was associated with free granules and 43% was associated with synaptosomes. Ovariectomy did not alter the postnatal changes in the fractional distribution of LHRH between these two subcellular compartments The LHRH content of the hypothalamus as well as the amount of LHRH sequestered in free ...