Endocrinology, Vol 104, 506-509, Copyright © 1979 by Endocrine Society

ARTICLES

Blockade of steroid-induced leuteinizing hormone release by selective depletion of anterior hypothalamic norepinephrine activity

JW Simpkins, JP Advis, CA Hodson and J Meites

Female Sprague-Dawley rats, weighing 200--225 g, were ovariectomized and, 10 days later, were given a single sc injection of 10 micrograms estradiol benzoate/100 g BW. Three days after estradiol benzoate treatment, animals received 50 micrograms progesterone (P)/100 g BW, resulting in a surge in LH release 7 and 9 h later. To determine the locus of the noradrenergic component of the P-induced LH surge, 6- hydroxydopamine (6-OH-DA), a neutrotoxin, was implanted into either the suprachiasmatic region or the median eminence (ME) 24 h before P administration. An implant of 6-OH-DA in the suprachiasmatic region decreased anterior hypothalamic norepinephrine concentration by 83%, anterior hypothalamic dopamine concentration by 24%, and eliminated the P-induced LH surge. ME implant of 6-OH-DA decreased norepinephrine concentration by 57% without affecting dopamine concentration, but was unable to alter the P. induced LH surge. These results indicate that the anterior hypothalamic noradrenergic system is necessary for the P- induced LH surge in ovariectomized rats and that noradrenergic nerve terminals in the ME are not involved in this process.

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				J. M. Goldman, A. S. Murr, A. R. Buckalew, and R. L. Cooper Suppression of the Steroid-Primed Luteinizing Hormone Surge in the Female Rat by Sodium Dimethyldithiocarbamate: Relationship to Hypothalamic Catecholamines and GnRH Neuronal Activation Toxicol. Sci., July 1, 2008; 104(1): 107 - 112. [Abstract] [Full Text] [PDF]