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Title: EXOGENOUS LEPTIN ADVANCES PUBERTY IN DOMESTIC HEN

Author
item PACZOSKA-ELIASIEWICZ, H
item PROSZKOWIEC-WEGLARZ, M
item Proudman, John
item JACEK, T
item MIKA, M
item SECHMAN, A
item RZASA, J
item GERTLER, A

Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2005
Publication Date: 12/20/2006
Citation: Paczoska-Eliasiewicz, H.E., Proszkowiec-Weglarz, M., Proudman, J.A., Jacek, T., Mika, M., Sechman, A., Rzasa, J., Gertler, A. 2006. Exogenous leptin advances puberty in domestic hen. Domestic Animal Endocrinology. 31(3):211-226.

Interpretive Summary: Although leptin is best known as an appetite-regulating hormone that controls weight gain and fat deposition, it is becoming increasingly clear from studies in mammals that leptin is also important in regulating the onset of puberty and normal reproductive function. The role of leptin is poorly understood in birds, and this study was conducted to examine whether leptin plays a physiological role in the development of the avian ovary, and whether it may attenuate the known effects of feed restriction on retarding sexual maturity. The results of two experiments showed that administration of recombinant chicken leptin significantly advanced sexual maturity in full-fed birds and restored the normal timing of sexual maturity in birds raised on a restricted feeding program. Analysis of the follicles of the ovaries of control and treated birds indicated that the observed advancement in sexual maturation with leptin treatment was due to a reduction in programmed cell death (apoptosis) in follicles that were growing to the size required for ovulation. Since feed restriction of broiler breeder hens is widely used for body weight control, these results are important in understanding the interactions of metabolic regulatory hormones and nutrition in the onset of sexual maturity and initiation of normal reproduction. The results will be used by scientists to optimize the reproductive efficiency of breeder hens.

Technical Abstract: We conducted two experiments to examine a possible role of leptin in: 1) enhancing prepubertal ovarian development and sexual maturation in the chicken, and 2) attenuating the known effect of feed restriction on retarding sexual maturation. In the first experiment we injected immature pullets (77 days of age) with leptin daily, at four dose levels (4, 16, 64 and 256 µg/kg body weight) until sexual maturity (lay of the first egg). Leptin treatment at the highest dose significantly (P<0.05) advanced the onset of puberty (day 116.3 ± 1.06) in comparison to controls (day 121.3 ± 1.24). The prepubertal rises of LH, estradiol (E2) and progesterone (P4) in blood plasma were also advanced by leptin treatment. In the second experiment, both full-fed and feed-restricted pullets were injected daily with leptin (256 µg/kg body weight). In birds fed ad libitum, exogenous leptin again significantly (P<0.05) advanced first ovipostion, while abolished the significant (P<0.05) delay caused by feed restriction and restored the normal timing of sexual maturity. Analysis of the ovaries in 106- day-old pullets revealed that leptin injections advanced follicular development, particularly in birds fed ad libitum, and significantly (P<0.01) reduced follicular apoptosis both in full-fed and feed-restricted birds. In conclusion, we have shown that in female chickens leptin participates in the regulation of puberty by attenuation of ovarian apoptosis and enhancement of folliculogenesis.