Many LH peaks are needed to physiologically stimulate testosterone secretion: modulation by fasting and NPY
| Autor: | Dominique D. Pierroz, Michel L. Aubert, Ilpo Huhtaniemi, Audrey Aebi |
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| Rok vydání: | 1999 |
| Předmět: |
Activity Cycles
Male medicine.medical_specialty Testosterone/blood/secretion Physiology medicine.drug_class Luteinizing Hormone/blood/secretion Seminal Vesicles/drug effects/physiology Endocrinology Diabetes and Metabolism Pulsatile flow Stimulation Biology Cerebral Ventricles Rats Sprague-Dawley Fasting/physiology Physiology (medical) Internal medicine Cerebral Ventricles/drug effects/physiology Testis medicine Animals Homeostasis Organ Size/drug effects Infusions Parenteral Neuropeptide Y Testosterone Secretion Testis/drug effects/physiology ddc:618 Seminal Vesicles Fasting Organ Size Luteinizing Hormone Androgen Neuropeptide Y receptor Rats Endocrinology Neuropeptide Y/administration & dosage/pharmacology Gonadotropin Luteinizing hormone |
| Zdroj: | American Journal of Physiology, Vol. 276, No 4 Pt 1 (1999) pp. E603-10 |
| ISSN: | 1522-1555 0193-1849 0002-9513 |
| DOI: | 10.1152/ajpendo.1999.276.4.e603 |
| Popis: | The pulsatile luteinizing hormone (LH) and testosterone secretions were studied during serial blood collections performed at 7-min time intervals in the male rat. In fed rats, a discontinuous pattern of LH secretion was observed. Periods without secretion alternated with active secretory episodes consisting in trains of three to four LH peaks that triggered testosterone secretion usually 1–2 h later. The magnitude of the testosterone response was not correlated with the amplitude of the LH peaks. Isolated, single peaks of LH did not evoke clear testosterone responses. Forty-eight hours after initiation of fasting, testosterone secretion was markedly decreased, but integrated LH secretion was only partly reduced. Chronic infusion of neuropeptide Y (NPY; 18 μg/day, icv) reduced testosterone secretion to very low levels and abolished pulsatile LH secretion or testosterone response to isolated LH peaks. In conclusion, the stimulation of testosterone secretion by LH necessitates several LH peaks organized in a proper sequence, and the testosterone response is not immediate. Low testosterone secretion in fasting rats appears to result from disappearance of coordinated, multiple LH peaks of sufficient size. Inhibition of the gonadotropic axis achieved by central NPY administration is due to either absence of LH peak “clusters” or occurrence of nonfunctional single LH peaks. |
| Databáze: | OpenAIRE |
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