title: Testicular regulation of sexual dimorphisms in the ultradian profiles of circulating growth hormone in the chicken.
abstract: Ultradian patterns in plasma growth hormone (GH) concentrations were determined in adult white Leghorn roosters, hens and capons. Serial blood samples were collected every 15 min over 8 h through surgically placed chronic indwelling right atrial catheters and assayed for GH content by a GH content by a homologous radioimmunoassay. In both sexes, GH levels fluctuated episodically, with peak and interpeak periods each lasting about 45 min in both roosters and hens. However, GH concentrations in the peaks and nadirs were 2.5-3.5 times greater in the plasma GH profiles of roosters as compared to hens, which resulted in roosters having higher mean GH concentrations. Caponizing completely feminized the episodic GH secretory profile. In contrast to chickens, the common sexually dimorphic feature in secretory GH profiles of mammals is the enhanced peak frequencing found in females.
authors.affiliation: Laboratories of Biochemistry, University of Pennsylvania School of Veterinary Medicine, Philadelphia 19104-6048.
authors.forename: N A
authors.initials: NA
authors.lastname: Pampori
authors.forename: B H
authors.initials: BH
authors.lastname: Shapiro
mesh_terms: D000204:Activity Cycles; D000818:Animals; D002645:Chickens / Q000097:blood / Q000502:physiology*; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D008297:Male; D009919:Orchiectomy; D009994:Osmolar Concentration; D012727:Sex Characteristics; D013737:Testis / Q000502:physiology*
chemical_list: D013006:Growth Hormone