Endocrinology, Vol 120, 491-496, Copyright © 1987 by Endocrine Society

ARTICLES

Hormonal regulation of the peripubertal surge of insulin-like growth factor-I in the rat

DJ Handelsman, JA Spaliviero, CD Scott and RC Baxter

The marked increase in circulating insulin-like growth factor-I (IGF-I) levels during puberty observed in primates indicates an important functional relationship between hypothalamic-pituitary gonadal function and hormonal regulation of peripubertal circulating IGF-I levels. Recent studies demonstrating local production and secretion of gonadal peptides including IGF-I suggest that increased circulating IGF-I levels during puberty might be due to direct gonadal secretion of IGF-I or alternatively to indirect effects of increased gonadal steroid secretion on nongonadal tissues including the hypothalamus, pituitary, and liver. We therefore studied the effects of prepubertal castration on the pubertal IGF-I surge and demonstrate that castration provokes a further increase rather than ablation of the pubertal IGF-I surge in the rat. Furthermore, neonatal treatment with monosodium glutamate, a hypothalamic neurotoxin, abolishes the pubertal IGF-I surge when commenced on postnatal day 1 but not on day 5, whereas treatment with a GnRH antagonist commencing within 12 h of birth significantly reduces but does not abolish the pubertal IGF-I surge. We therefore propose that the pubertal IGF-I surge in the rat is not due to direct gonadal secretion of IGF-I or other gonadal hormones during puberty but may involve hypothalamic and/or hepatic programming by events during prenatal or very early postnatal life.

This article has been cited by other articles:

				R. Xiao, L. J Hennings, T. M Badger, and F. A Simmen Fetal programing of colon cancer in adult rats: correlations with altered neonatal growth trajectory, circulating IGF-I and IGF binding proteins, and testosterone J. Endocrinol., October 1, 2007; 195(1): 79 - 87. [Abstract] [Full Text] [PDF]

				S. S. Daftary and A. C. Gore IGF-1 in the Brain as a Regulator of Reproductive Neuroendocrine Function Experimental Biology and Medicine, May 1, 2005; 230(5): 292 - 306. [Abstract] [Full Text] [PDF]

				D. Vanderschueren, L. Vandenput, S. Boonen, M. K. Lindberg, R. Bouillon, and C. Ohlsson Androgens and Bone Endocr. Rev., June 1, 2004; 25(3): 389 - 425. [Abstract] [Full Text] [PDF]

				S. S. Daftary and A. C. Gore Developmental Changes in Hypothalamic Insulin-Like Growth Factor-1: Relationship to Gonadotropin-Releasing Hormone Neurons Endocrinology, May 1, 2003; 144(5): 2034 - 2045. [Abstract] [Full Text] [PDF]

				T. P. Combs, A. H. Berg, M. W. Rajala, S. Klebanov, P. Iyengar, J. C. Jimenez-Chillaron, M. E. Patti, S. L. Klein, R. S. Weinstein, and P. E. Scherer Sexual Differentiation, Pregnancy, Calorie Restriction, and Aging Affect the Adipocyte-Specific Secretory Protein Adiponectin Diabetes, February 1, 2003; 52(2): 268 - 276. [Abstract] [Full Text] [PDF]

				E. Carro, A. Nunez, S. Busiguina, and I. Torres-Aleman Circulating Insulin-Like Growth Factor I Mediates Effects of Exercise on the Brain J. Neurosci., April 15, 2000; 20(8): 2926 - 2933. [Abstract] [Full Text] [PDF]

				W. L. Dees, G. A. Dissen, J. K. Hiney, F. Lara, and S. R. Ojeda Alcohol Ingestion Inhibits the Increased Secretion of Puberty-Related Hormones in the Developing Female Rhesus Monkey Endocrinology, April 1, 2000; 141(4): 1325 - 1331. [Abstract] [Full Text] [PDF]

				D.L. Foster and S. Nagatani Physiological Perspectives on Leptin as a Regulator of Reproduction: Role in Timing Puberty Biol Reprod, February 1, 1999; 60(2): 205 - 215. [Abstract] [Full Text] [PDF]

				J. Frystyk, H. Gronbak, C. Skjarbak, A. Flyvbjerg, H. Orskov, and R. C. Baxter Developmental Changes in Serum Levels of Free and Total Insulin-Like Growth Factor I (IGF-I), IGF-Binding Protein-1 and -3, and the Acid-Labile Subunit in Rats Endocrinology, October 1, 1998; 139(10): 4286 - 4292. [Abstract] [Full Text] [PDF]

				R. L. Duerr, M. D. McKirnan, R. D. Gim, R. G. Clark, K. R. Chien, and J. Ross Jr Cardiovascular Effects of Insulin-Like Growth Factor-1 and Growth Hormone in Chronic Left Ventricular Failure in the Rat Circulation, June 15, 1996; 93(12): 2188 - 2196. [Abstract] [Full Text]