Acceleration of maturation of FSH and LH responses to photostimulation in prepubertal domestic hens by oestrogen

in Reproduction
View More View Less
Free access

Egg laying begins in domestic hens, reared on short daylengths, at about day 147 of age and is advanced by photostimulation after but not before about day 42 of age. The development of this response at day 42 may be facilitated by oestrogen. This hypothesis was investigated in prepubertal hens, reared on short daylengths, by comparing the effects of oestrogen treatment on pituitary and plasma FSH and LH responses to photostimulation (16 h light:8 h dark) for 1 week at days 34 and 54 of age. Oestradiol benzoate (0.5 mg kg(-1)) was injected i.m. on alternate days for 1 week before and after photostimulation. At day 34, pituitary LH content increased after photostimulation but plasma LH and FSH concentrations did not increase. At day 54, pituitary FSH content and plasma FSH and LH concentrations increased after photostimulation, whereas pituitary LH content did not increase. At days 34 and 54, oestrogen treatment decreased pituitary FSH and LH contents but did not block the stimulatory effect of photostimulation on pituitary FSH. At day 34 but not at day 54, photostimulation combined with oestrogen treatment increased plasma FSH and LH concentrations. Plasma LH but not plasma FSH concentration increased after GnRH-I injection at days 34 and 54. These observations are consistent with the hypothesis that, in prepubertal female chickens, maturation of the neuroendocrine mechanism mediating photoinduced FSH and LH release may be mediated by oestrogen. This effect of oestrogen on photoinduced LH release may be mediated by increased GnRH-I release or enhanced pituitary responsiveness to GnRH-I. It is proposed that neuroendocrine mechanisms controlling photoinduced FSH release may involve oestrogen-responsive interactions between pituitary paracrine factors, including activins and follistatin.

 

     An official journal of

    Society for Reproduction and Fertility

 

Sept 2018 onwards Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 191 57 2
PDF Downloads 341 92 9