Concentrations of Pituitary, Gonadal and Adrenal Hormones in Serum of Laying and Broody White Rock Hens (Gallus Domesticus)

Abstract

Diurnal variations in circulating concentrations of LH, GH, prolactin, corticosterone, oestradiol, progesterone and testosterone were followed in laying and broody White Rock domestic fowl. Throughout the 24 h study prolactin concentrations in serum were consistently (two- to fourfold) higher in broody than in laying birds, in which the prolactin level varied with the light:darkness or ovulatory cycles. Concentrations of GH in serum tended to be lower in broody birds but in both groups were very variable and showed no obvious relationship with either the lighting or ovulatory cycles. Broodiness was also characterized by low LH and gonadal steroid levels and by the absence of preovulatory peaks in the serum concentrations of these hormones. A diurnal rhythm in corticosterone was observed in both the laying and broody birds, with high levels during the period of darkness. Corticosterone concentrations were markedly higher in the broody birds than in laying birds during most of the 24 h study. No diurnal rhythm in the blood haematocrit level was observed in either group, although the level was generally lower in broody birds. This difference, however, was insufficient to account for the lower LH and gonadal steroid levels in the broody birds. The results suggest that prolactin is involved in the initiation or maintenance of broodiness in the fowl and the possibility of an antigonadal role for the hormone is discussed.

Plasma concentrations of luteinizing hormone growth hormone, oestradiol, testosterone and androstenedione in the domestic hen from 6 weeks of age to sexual maturity

“…The concentrations of GH in the plasma of immature birds (6-20 weeks) followed a similar pattern of changes to those reported by Harvey et al (1979) and Scanes et al (1980) Sharp, 1979 ;Bedrak, Harvey and Chadwick, 1981). ).…”

Comparative Changes in the Serum Concentrations of Inhibin-B, Prolactin, Gonadotropins and Steroid Hormones at Different Reproductive States in Domestic Turkey Hens

“…The prolonged elevation of the levels of prolactin during the incubation period has an antisteroidogenic effect on the ovary [58][59][60][61] in part via inhibition of steroidogenic enzyme gene expression [57].…”

Effect of growth hormone on steroid content, proliferation and apoptosis in the chicken ovary during sexual maturation

“…The increase in plasma GH concentration in chickens at the time of maturation (Williams et al 1986) and before oviposition ) and the suppression of GH secretion in chicken, turkey and bantam hens during the cessation of egg laying Sharp et al 1979;Bedrak et al 1981) suggest that, in birds, GH might participate in reproduction, as it does in mammals. GH receptors in the granulosa and theca layers of preovulatory follicles (Lebedeva et al 2004) and GH receptor (GHR) mRNA in the ovaries of growing broiler breeder chickens (Heck et al 2003) have also been reported.…”