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Circulating estradiol suppresses luteinizing hormone pulse frequency during dietary restriction.
Renquist, Benjamin J; Calvert, Christopher C; Adams, Betty M; Adams, Thomas E.
Affiliation
  • Renquist BJ; Department of Animal Science, Meyer Hall, University of California, One Shields Avenue, Davis, CA 95616, United States.
Domest Anim Endocrinol ; 34(3): 301-10, 2008 Apr.
Article in En | MEDLINE | ID: mdl-17904783
ABSTRACT
The influence of dietary restriction on the negative feedback potency of 17-beta-estradiol (E2) was evaluated in both castrated male (wethers) and female sheep (OVX ewes) during the breeding season. In study 1, OVX ewes received maintenance or restricted dietary energy for 7 weeks or maintenance energy for 6 weeks prior to a 5 day fast (n=12ewes/feeding group). Estradiol (0.31microg E2/50kg/h) or vehicle (10% EtOH-saline) was continuously infused into half the animals in each dietary treatment for the final 54h of the study. The dynamic pattern of LH secretion was assessed during the final 6h of infusion. Estradiol inhibited luteinizing hormone (LH) pulse amplitude independent of nutrition (P=0.02); fasting increased mean LH, LH peak height, and LH nadir in the absence of E2 (P=0.004, P=0.02, and P=0.02, respectively); while E2 inhibited pulse frequency (P=0.02) and increased peak width (P=0.04) in restricted ewes. Interestingly, despite uniform E2 delivery, serum concentrations of E2 differed with feeding status. Therefore, 12 wethers were infused with 0.31microg E2/50kg/h (6 fed, 6 fasted) and six wethers received 0.19microg E2/50kg/h (fasted) to establish similar serum concentrations of E2 in fed (0.31microg/50kg/h) and fasted (0.19microg/50kg/h) wethers. When fed and fasted wethers had uniform serum concentrations of E2 LH pulse frequency was suppressed (P<0.05) in fasted relative to fed animals, supporting the postulate that energy restriction enhances the E2 negative feedback potency. Collectively, these studies demonstrate that nutrition affects E2 feedback potency and clearance.
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Collection: 01-internacional Database: MEDLINE Main subject: Sheep / Luteinizing Hormone / Caloric Restriction / Estradiol Limits: Animals Language: En Journal: Domest Anim Endocrinol Journal subject: ENDOCRINOLOGIA / MEDICINA VETERINARIA Year: 2008 Type: Article Affiliation country: United States
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Collection: 01-internacional Database: MEDLINE Main subject: Sheep / Luteinizing Hormone / Caloric Restriction / Estradiol Limits: Animals Language: En Journal: Domest Anim Endocrinol Journal subject: ENDOCRINOLOGIA / MEDICINA VETERINARIA Year: 2008 Type: Article Affiliation country: United States