Regulation of the hypothalamic melanin-concentrating hormone neurons by sex steroids in the goldfish: possible role in the modulation of luteinizing hormone secretion.
In teleost fish, melanin-concentrating hormone (MCH) is a cyclic heptadecapeptide released from the pituitary during white background adaptation. In the periphery MCH concentrates melanin granules in melanophores thus lightening the body color of fish. Evidence from mammalian studies has demonstrated the involvement of MCH in the control of energy balance and the reproductive axis. Information about the hormonal regulation of MCH neurons in non-mammalian systems is scarce and nothing is known about its role in the regulation of the reproductive axis. We here report the molecular characterization of two MCH precursors in the goldfish. Both precursors are peripherally expressed and the expression in the central nervous system is restricted to the mediobasal hypothalamus. Hypothalamic MCH-mRNA production is upregulated during white background adaptation. Both testosterone and estradiol stimulate MCH mRNA expression in the hypothalamus in a sex-dependent manner, with females showing the greatest responsiveness. In addition, in vitro experiments demonstrated that graded doses of salmon MCH stimulate LH, but not GH, secretion from dispersed pituitary cells. Results suggest that hypothalamic MCH may participate in the steroid positive feedback loop on pituitary LH secretion.
Cerdá-Reverter
José Miguel
JM
Department of Biological Sciences, University of Alberta, Edmonton, Alta., Canada. cerdarev@iats.csic.es
Canosa
Luis Fabian
LF
Peter
Richard Ector
RE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006054:Goldfish; D013006:Growth Hormone / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000235:genetics / Q000378:metabolism*; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008543:Melanins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010907:Pituitary Hormones / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012727:Sex Characteristics; D013739:Testosterone / Q000494:pharmacology*
D007028:Hypothalamic Hormones; D008543:Melanins; D010907:Pituitary Hormones; D012333:RNA, Messenger; D013739:Testosterone; D004958:Estradiol; C019463:melanin-concentrating hormone; D007986:Luteinizing Hormone; D013006:Growth Hormone