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Interactions of testosterone and short-photoperiod exposure on the neuroendocrine axis of the male Syrian hamster. 1986

R W Steger, and K S Matt, and A Bartke

Exposure of adult male golden hamsters to short days (less than 12.5 h light/day) leads to suppression of gonadal function which is secondary to reductions in gonadotropin and prolactin (PRL) secretion. Short-day (SD) exposure also leads to a reduction in hypothalamic norepinephrine (NE) and dopamine (DA) metabolism and an increase in hypothalamic LHRH content which appears to be related to a decrease in LHRH release. To determine whether SD-induced changes in NE and DA metabolism are dependent or independent of changes in circulating testosterone (T) levels and thus possible mediators of photoperiod effects on gonadotropin secretion, the effects of castration and steroid replacement on hypothalamic amine metabolism were studied in male hamsters maintained under long or short photoperiod conditions. The presence of Silastic T-implants resulted in a greater suppression of LH and FSH in SD than in long-day (LD) hamster, but increased median eminence (ME) LHRH content in both groups. Exposure of castrate hamsters to short days led to a reduction of NE turnover in the ME and medial preoptic-suprachiasmatic area (MPOA) and a decrease in serum FSH levels. LH levels tended to be lower, but not significantly so. The decrease in ME NE turnover was potentiated by T replacement, but in the MPOA-SCN, T-implants reversed the effects of short days. NE turnover in the MBH was reduced by T in both LD and SD animals, but the effect was much greater in the SD animals. SD exposure also caused a decrease in ME DA metabolism that was reversed by T replacement.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007031 Hypothalamus Ventral part of the DIENCEPHALON extending from the region of the OPTIC CHIASM to the caudal border of the MAMMILLARY BODIES and forming the inferior and lateral walls of the THIRD VENTRICLE. Lamina Terminalis,Preoptico-Hypothalamic Area,Area, Preoptico-Hypothalamic,Areas, Preoptico-Hypothalamic,Preoptico Hypothalamic Area,Preoptico-Hypothalamic Areas
D007986 Luteinizing Hormone A major gonadotropin secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Luteinizing hormone regulates steroid production by the interstitial cells of the TESTIS and the OVARY. The preovulatory LUTEINIZING HORMONE surge in females induces OVULATION, and subsequent LUTEINIZATION of the follicle. LUTEINIZING HORMONE consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH and FSH), but the beta subunit is unique and confers its biological specificity. ICSH (Interstitial Cell Stimulating Hormone),Interstitial Cell-Stimulating Hormone,LH (Luteinizing Hormone),Lutropin,Luteoziman,Luteozyman,Hormone, Interstitial Cell-Stimulating,Hormone, Luteinizing,Interstitial Cell Stimulating Hormone
D007987 Gonadotropin-Releasing Hormone A decapeptide that stimulates the synthesis and secretion of both pituitary gonadotropins, LUTEINIZING HORMONE and FOLLICLE STIMULATING HORMONE. GnRH is produced by neurons in the septum PREOPTIC AREA of the HYPOTHALAMUS and released into the pituitary portal blood, leading to stimulation of GONADOTROPHS in the ANTERIOR PITUITARY GLAND. FSH-Releasing Hormone,GnRH,Gonadoliberin,Gonadorelin,LH-FSH Releasing Hormone,LHRH,Luliberin,Luteinizing Hormone-Releasing Hormone,Cystorelin,Dirigestran,Factrel,Gn-RH,Gonadorelin Acetate,Gonadorelin Hydrochloride,Kryptocur,LFRH,LH-RH,LH-Releasing Hormone,LHFSH Releasing Hormone,LHFSHRH,FSH Releasing Hormone,Gonadotropin Releasing Hormone,LH FSH Releasing Hormone,LH Releasing Hormone,Luteinizing Hormone Releasing Hormone,Releasing Hormone, LHFSH
D008027 Light That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range. Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D008297 Male Males
D008473 Median Eminence Raised area at the infundibular region of the HYPOTHALAMUS at the floor of the BRAIN, ventral to the THIRD VENTRICLE and adjacent to the ARCUATE NUCLEUS OF HYPOTHALAMUS. It contains the terminals of hypothalamic neurons and the capillary network of hypophyseal portal system, thus serving as a neuroendocrine link between the brain and the PITUITARY GLAND. Eminentia Mediana,Medial Eminence,Eminence, Medial,Eminence, Median,Eminences, Medial,Eminentia Medianas,Medial Eminences,Mediana, Eminentia,Medianas, Eminentia
D008647 Mesocricetus A genus in the order Rodentia and family Cricetidae. One species, Mesocricetus auratus or golden hamster is widely used in biomedical research. Hamsters, Golden,Hamsters, Golden Syrian,Hamsters, Syrian,Mesocricetus auratus,Syrian Golden Hamster,Syrian Hamster,Golden Hamster,Golden Hamster, Syrian,Golden Hamsters,Golden Syrian Hamsters,Hamster, Golden,Hamster, Syrian,Hamster, Syrian Golden,Syrian Hamsters
D009490 Neurosecretory Systems A system of NEURONS that has the specialized function to produce and secrete HORMONES, and that constitutes, in whole or in part, an ENDOCRINE SYSTEM or organ. Neuroendocrine System,Neuroendocrine Systems,Neurosecretory System,System, Neuroendocrine,System, Neurosecretory,Systems, Neuroendocrine,Systems, Neurosecretory
D009638 Norepinephrine Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic. Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D009919 Orchiectomy The surgical removal of one or both testicles. Castration, Male,Orchidectomy,Castrations, Male,Male Castration,Male Castrations,Orchidectomies,Orchiectomies

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