Gonadotrophin-releasing hormone and GnRH-associated peptide neurobiology from the rearing period until puberty in the female sheep.
Using morphological criteria we describe the postnatal ontogeny of gonadotrophin-releasing hormone (GnRH) and GnRH-associated peptide (GAP) of the GnRH prohormone in the ovine preoptic area (POA)-hypothalamus. The immunohistochemical GnRH- and GAP-neuroanatomy was investigated in infantile (12-week-old weanlings), prepubertal (15-, 22-week-old juveniles), peripubertal (30-, 52-week-old during maturational quiescence) and pubertal (63-week-old) females born after the summer solstice, thus undergoing delayed puberty. The changes observed in the medial POA included a postinfantile increase in the number of multipolar GnRH-immunoreactive (ir) perikarya until late prepuberty (p < 0.05). Whereas in peripubertal lambs were observed both an increase in the number of GnRH-ir and GAP-ir cell clusters in the medial POA and an increase in the mediobasal hypothalamus (MBH) subpopulation of GnRH-ir and GAP-ir neurons (p < 0.05). The GnRH-ir perikarya, nerve fibers and terminals showed a progressive increase in numbers until peripuberty. Conversely, the acute postinfantile alterations of decrease and then increase in the population of GAP-ir nerve elements were observed in the POA-hypothalamus until late prepuberty (p < 0.05). The preoptico-hypothalamic ir GAP and GnRH were of comparable abundance in both peripubertal groups and scarce during puberty. In conclusion, the infantile/prepubertal transition period changes GnRH posttranslational biosynthesis and GnRH-GAP-neuroanatomy from the infantile to the pubertal pattern, which allows the inauguration of the breeding season. The postinfantile MBH distribution of GnRH-containing neurons and increase in the POA population of GnRH-GAP neurons and their somatic appositions seem important for maturation. The nature of GnRH-GAP neurobiology during inauguration of puberty seems morphotic and in female sheep is seasonal.
Wańkowska
Marta
M
Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jabłonna, Poland. m.wankowska@ifzz.pan.pl
Polkowska
Jolanta
J
D000375:Aging / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D002452:Cell Count; D015536:Down-Regulation / Q000502:physiology; D005260:Female; D005836:Genitalia, Female / Q000254:growth & development / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000254:growth & development* / Q000378:metabolism*; D007033:Hypothalamus, Middle / Q000254:growth & development / Q000378:metabolism; D007150:Immunohistochemistry; D009474:Neurons / Q000378:metabolism; D011301:Preoptic Area / Q000254:growth & development / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D012098:Reproduction / Q000502:physiology; D012621:Seasons; D034561:Sheep, Domestic / Q000254:growth & development* / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology
D011498:Protein Precursors; C050502:gonadotropin releasing hormone associated peptide; D007987:Gonadotropin-Releasing Hormone