Endocrinology, Vol 96, 57-62, Copyright © 1975 by Endocrine Society

ARTICLES

A daily signal for the LH surge in the rat

SJ Legan and FJ Karsch

We have demonstrated that a brief step-like increment in circulating estradiol concentrations to approximately 100 pg/ml, achieved by SC insertion of Silastic capsules containing estradiol-17 beta and their withdrawal after 29 1/2 hr, elicited a daily LH surge on 4 consecutive afternoons in rats ovariectomized 2 weeks previously. Since the duration of this stimulus was similar to that of the preovulatory increment in serum estradiol concentrations, it was postulated that the endogenous estrogen signal in intact rats might also trigger repetitive LH surges if ovulation and formation of corpora lutea were prevented. To test this hypothesis, rats were ovariectomized at 10:00 AM on proestrus (day 1) and blood samples were obtained at 12:30 and 5:00 PM on days 1 to 4. Although an LH surge occurred on proestrus, no subsequent LH discharges were observed. The absence of an LH surge on consecutive days could not be attributed to a difference between the endogenous estradiol stimulus and the exogenous stimulus which elicited repetitive LH surges in long-term ovariectomized rats. Rather, it was determined that in recently ovariectomized rats, in contrast to long- term ovariectomized rats, a daily LH surge occurred only if elevated serum estradiol concentrations were maintained. Thus, by leaving implants in place, an LH discharge was elicited on 10 consecutive days. These results support the concept that a neural signal for the LH surge is emitted each day throughout the estrous cycle of the rat, and that prolonged maintenance of elevated circulating estradiol concentrations is essential for the expression of these signals.

This article has been cited by other articles:

				C. A. Christian and S. M. Moenter Vasoactive Intestinal Polypeptide Can Excite Gonadotropin-Releasing Hormone Neurons in a Manner Dependent on Estradiol and Gated by Time of Day Endocrinology, June 1, 2008; 149(6): 3130 - 3136. [Abstract] [Full Text] [PDF]

				C. A. Christian and S. M. Moenter Estradiol Induces Diurnal Shifts in GABA Transmission to Gonadotropin-Releasing Hormone Neurons to Provide a Neural Signal for Ovulation J. Neurosci., February 21, 2007; 27(8): 1913 - 1921. [Abstract] [Full Text] [PDF]

				Z. Shi, K. E. Valdez, A. Y. Ting, A. Franczak, S. L. Gum, and B. K. Petroff Ovarian Endocrine Disruption Underlies Premature Reproductive Senescence Following Environmentally Relevant Chronic Exposure to the Aryl Hydrocarbon Receptor Agonist 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Biol Reprod, February 1, 2007; 76(2): 198 - 202. [Abstract] [Full Text] [PDF]

				B. H. Miller, S. L. Olson, J. E. Levine, F. W. Turek, T. H. Horton, and J. S. Takahashi Vasopressin Regulation of the Proestrous Luteinizing Hormone Surge in Wild-Type and Clock Mutant Mice Biol Reprod, November 1, 2006; 75(5): 778 - 784. [Abstract] [Full Text] [PDF]

				B. N. Karman and S. A. Tischkau Circadian Clock Gene Expression in the Ovary: Effects of Luteinizing Hormone Biol Reprod, October 1, 2006; 75(4): 624 - 632. [Abstract] [Full Text] [PDF]

				C. A. Christian, J. L. Mobley, and S. M. Moenter Diurnal and estradiol-dependent changes in gonadotropin-releasing hormone neuron firing activity PNAS, October 25, 2005; 102(43): 15682 - 15687. [Abstract] [Full Text] [PDF]

				J. T. Smith, M. J. Cunningham, E. F. Rissman, D. K Clifton, and R. A. Steiner Regulation of Kiss1 Gene Expression in the Brain of the Female Mouse Endocrinology, September 1, 2005; 146(9): 3686 - 3692. [Abstract] [Full Text] [PDF]

				E. N. Ottem, J. G. Godwin, S. Krishnan, and S. L. Petersen Dual-Phenotype GABA/Glutamate Neurons in Adult Preoptic Area: Sexual Dimorphism and Function J. Neurosci., September 15, 2004; 24(37): 8097 - 8105. [Abstract] [Full Text] [PDF]

				H.-W. Tsai, P. S. LaPolt, A. P. Olcott, and J. K.H. Lu Temporal Changes Occur in the Neuroendocrine Control of Gonadotropin Secretion in Aging Female Rats: Role of Progesterone Biol Reprod, September 1, 2004; 71(3): 845 - 852. [Abstract] [Full Text] [PDF]

				K. L. Britt, P. G. Stanton, M. Misso, E. R. Simpson, and J. K. Findlay The Effects of Estrogen on the Expression of Genes Underlying the Differentiation of Somatic Cells in the Murine Gonad Endocrinology, August 1, 2004; 145(8): 3950 - 3960. [Abstract] [Full Text] [PDF]

				M. M. Mahoney, C. Sisk, H. E. Ross, and L. Smale Circadian Regulation of Gonadotropin-Releasing Hormone Neurons and the Preovulatory Surge in Luteinizing Hormone in the Diurnal Rodent, Arvicanthis niloticus, and in a Nocturnal Rodent, Rattus norvegicus Biol Reprod, April 1, 2004; 70(4): 1049 - 1054. [Abstract] [Full Text] [PDF]

				P. E. Chappell, R. S. White, and P. L. Mellon Circadian Gene Expression Regulates Pulsatile Gonadotropin-Releasing Hormone (GnRH) Secretory Patterns in the Hypothalamic GnRH-Secreting GT1-7 Cell Line J. Neurosci., December 3, 2003; 23(35): 11202 - 11213. [Abstract] [Full Text] [PDF]

				B. K. Petroff, C. R. Croutch, D. M. Hunter, M. E. Wierman, and X. Gao 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) Stimulates Gonadotropin Secretion in the Immature Female Sprague-Dawley Rat Through a Pentobarbital- and Estradiol-Sensitive Mechanism but Does Not Alter Gonadotropin-Releasing Hormone (GnRH) Secretion by Immortalized GnRH Neurons In Vitro Biol Reprod, June 1, 2003; 68(6): 2100 - 2106. [Abstract] [Full Text] [PDF]

				H.-W. Tsai and S. J. Legan Loss of Luteinizing Hormone Surges Induced by Chronic Estradiol Is Associated with Decreased Activation of Gonadotropin-Releasing Hormone Neurons Biol Reprod, April 1, 2002; 66(4): 1104 - 1110. [Abstract] [Full Text] [PDF]

				J.-I. Park, H.-J. Park, H.-S. Choi, K. Lee, W.-K. Lee, and S.-Y. Chun Gonadotropin Regulation of NGFI-B Messenger Ribonucleic Acid Expression during Ovarian Follicle Development in the Rat Endocrinology, July 1, 2001; 142(7): 3051 - 3059. [Abstract] [Full Text] [PDF]

				K. Krajnak, K. L. Rosewell, and P. M. Wise Fos-Induction in Gonadotropin-Releasing Hormone Neurons Receiving Vasoactive Intestinal Polypeptide Innervation Is Reduced in Middle-Aged Female Rats Biol Reprod, April 1, 2001; 64(4): 1160 - 1164. [Abstract] [Full Text]

				C. B. Herath, G. Watanabe, S.-i. Katsuda, M. Yoshida, A. K. Suzuki, and K. Taya Exposure of Neonatal Female Rats to p-tert-Octylphenol Disrupts Afternoon Surges of Luteinizing Hormone, Follicle-Stimulating Hormone and Prolactin Secretion, and Interferes with Sexual Receptive Behavior in Adulthood Biol Reprod, April 1, 2001; 64(4): 1216 - 1224. [Abstract] [Full Text]

				H.-W. Tsai and S. J. Legan Chronic Elevation of Estradiol in Young Ovariectomized Rats Causes Aging-Like Loss of Steroid-Induced Luteinizing Hormone Surges Biol Reprod, February 1, 2001; 64(2): 684 - 688. [Abstract] [Full Text]

				V. Prevot, S. Bouret, D. Croix, G. Alonso, L. Jennes, V. Mitchell, A. Routtenberg, and J.-C. Beauvillain Growth-Associated Protein-43 Messenger Ribonucleic Acid Expression in Gonadotropin-Releasing Hormone Neurons during the Rat Estrous Cycle Endocrinology, May 1, 2000; 141(5): 1648 - 1657. [Abstract] [Full Text] [PDF]

				P. E. Chappell and J. E. Levine Stimulation of Gonadotropin-Releasing Hormone Surges by Estrogen. I. Role of Hypothalamic Progesterone Receptors Endocrinology, April 1, 2000; 141(4): 1477 - 1485. [Abstract] [Full Text] [PDF]

				T. L. McElhinny, C. L. Sisk, K. E. Holekamp, and L. Smale A Morning Surge in Plasma Luteinizing Hormone Coincides with Elevated Fos Expression in Gonadotropin-Releasing Hormone-Immunoreactive Neurons in the Diurnal Rodent, Arvicanthis niloticus Biol Reprod, October 1, 1999; 61(4): 1115 - 1122. [Abstract] [Full Text]

				F. Tejada, A. Cremades, M. Aviles, M. T. Castells, and R. Penafiel Hypokalemia alters sex hormone and gonadotropin levels: evidence that FSH may be required for luteinization Am J Physiol Endocrinol Metab, December 1, 1998; 275(6): E1037 - E1045. [Abstract] [Full Text] [PDF]

				K. Krajnak, M. L. Kashon, K. L. Rosewell, and P. M. Wise Sex Differences in the Daily Rhythm of Vasoactive Intestinal Polypeptide But Not Arginine Vasopressin Messenger Ribonucleic Acid in the Suprachiasmatic Nuclei Endocrinology, October 1, 1998; 139(10): 4189 - 4196. [Abstract] [Full Text] [PDF]

				K. Krajnak, M. L. Kashon, K. L. Rosewell, and P. M. Wise Aging Alters the Rhythmic Expression of Vasoactive Intestinal Polypeptide mRNA But Not Arginine Vasopressin mRNA in the Suprachiasmatic Nuclei of Female Rats J. Neurosci., June 15, 1998; 18(12): 4767 - 4774. [Abstract] [Full Text] [PDF]

				A. Mukherjee, J. Urban, P. Sassone-Corsi, and K. E. Mayo Gonadotropins Regulate Inducible Cyclic Adenosine 3',5'-Monophosphate Early Repressor in the Rat Ovary: Implications for Inhibin {alpha} Subunit Gene Expression Mol. Endocrinol., June 1, 1998; 12(6): 785 - 800. [Abstract] [Full Text]

				T. L. Horvath Suprachiasmatic Efferents Avoid Phenestrated Capillaries but Innervate Neuroendocrine Cells, Including Those Producing Dopamine Endocrinology, March 1, 1997; 138(3): 1312 - 1320. [Abstract] [Full Text] [PDF]

				V. Ramirez, D Dluzen, and D Lin Progesterone administration in vivo stimulates release of luteinizing hormone-releasing hormone in vitro Science, May 30, 1980; 208(4447): 1037 - 1039. [Abstract] [PDF]

				M. Stetson and M Watson-Whitmyre Nucleus suprachiasmaticus: the biological clock in the hamster? Science, January 16, 1976; 191(4223): 197 - 199. [Abstract] [PDF]