Effects of galanin-like peptide on luteinizing hormone secretion in the rat: sexually dimorphic responses and enhanced sensitivity at male puberty.

Full Abstract

Reproductive function is exquisitely sensitive to adequacy of nutrition and fuel reserves, through mechanisms that are yet to be completely elucidated. Galanin-like peptide (GALP) has recently emerged as another neuropeptide link that couples reproduction and metabolism. However, although the effects of GALP on luteinizing hormone (LH) secretion have been studied, no systematic investigation on how these responses might differ along sexual maturation and between sexes has been reported. Moreover, the influence of metabolic status and potential interplay with other relevant neurotransmitters controlling LH secretion remain ill defined. These facets of GALP physiology were addressed herein. Intracerebral injection of GALP to male rats induced a dose-dependent increase in serum LH levels, the magnitude of which was significantly greater in pubertal than in adult males. In contrast, negligible LH responses to GALP were detected in pubertal or adult female rats at diestrus. Neonatal androgen treatment to females failed to "masculinize" the pattern of LH response to GALP. In addition, metabolic stress by short-term fasting did not prevent but rather amplified LH responses to GALP in pubertal males, whereas these responses were abrogated by pharmacological inhibition of nitric oxide synthesis. We conclude that the ability of GALP to evoke LH secretion is sexually differentiated, with maximal responses at male puberty, a phenomenon which was not reverted by manipulation of sex steroid milieu during the critical neonatal period and was sensitive to metabolic stress. This state of LH hyperresponsiveness may prove relevant for the mechanisms relaying metabolic status to the reproductive axis in male puberty.

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Author information

Author/s: Castellano, J M (JM); Navarro, V M (VM); Fernández-Fernández, R (R); Roa, J (J); Vigo, E (E); Pineda, R (R); Steiner, R A (RA); Aguilar, E (E); Pinilla, L (L); Tena-Sempere, M (M);

Affiliation: Dept. of Cell Biology, Physiology, and Immunology, University of Córdoba, Avda. Menéndez Pidal, 14004 Córdoba, Spain.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: American journal of physiology. Endocrinology and metabolism (Am J Physiol Endocrinol Metab), published in United States. (Language: eng)

Reference: 2006-Dec; vol 291 (issue 6) : pp E1281-9

Dates: Created 2006/11/03; Completed 2006/12/12;

PMID: 16849629, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Androgens - pharmacology
Animals
Animals, Newborn
Data Interpretation, Statistical
Dose-Response Relationship, Drug
Excitatory Amino Acids - pharmacology
Fasting - metabolism
Female
Galanin-Like Peptide - pharmacology

Luteinizing Hormone - metabolism
Male
Nitric Oxide - physiology
Proteins - metabolism
Radioimmunoassay
Rats
Rats, Wistar
Sex Characteristics
Sexual Maturation - physiology

Associated Chemicals: Androgens (0) ; Excitatory Amino Acids (0) ; Galanin-Like Peptide (0) ; Kiss1 protein, rat (0) ; Proteins (0) ; Nitric Oxide (10102-43-9) ; Luteinizing Hormone (9002-67-9)

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