TY - JOUR
T1 - Patterns of preoptic-hypothalamic neuronal activation and LH secretion in female sheep following the introduction and withdrawal of novel males
AU - Hawken, Penny A.R.
AU - Smith, Jeremy T.
AU - Jorre De St Jorre, Trina
AU - Esmaili, Tammi
AU - Scott, Christopher J.
AU - Rodger, Jennifer
AU - Blache, Dominique
AU - Martin, Graeme B.
PY - 2019
Y1 - 2019
N2 - The neuroendocrine response of female sheep to a novel male involves neural activation in the hypothalamus. However, if males are removed, the gonadotrophic signal declines, so the neural activity is likely to change. We examined Fos-immunoreactive (IR) cells in hypothalamic tissues from seasonally anovulatory female sheep exposed to males for 2 or 6 h, or for 2 h followed by 4 h isolation from males. Control females were killed in the absence of male exposure. Male introduction increased LH secretion in all females; male removal was associated with a reduction only in mean and basal LH concentrations. Females exposed to males for 2 h had more Fos-IR cells in the arcuate nucleus (ARC), ventromedial nucleus of the hypothalamus (VMH) and organum vasculosum of the lamina terminalis (OVLT) than control females. Fos-IR cells in the preoptic area (POA) were only greater than in control females after 6 h exposure to a male. Removal of males decreased the number of Fos-IR cells in the ARC, VMH and OVLT, but not in the POA. Thus, hypothalamic neural activation and LH secretion in female sheep are stimulated by males and decline after male removal. However, activation in the POA persists after removal and may explain the incomplete decline in the LH response.
AB - The neuroendocrine response of female sheep to a novel male involves neural activation in the hypothalamus. However, if males are removed, the gonadotrophic signal declines, so the neural activity is likely to change. We examined Fos-immunoreactive (IR) cells in hypothalamic tissues from seasonally anovulatory female sheep exposed to males for 2 or 6 h, or for 2 h followed by 4 h isolation from males. Control females were killed in the absence of male exposure. Male introduction increased LH secretion in all females; male removal was associated with a reduction only in mean and basal LH concentrations. Females exposed to males for 2 h had more Fos-IR cells in the arcuate nucleus (ARC), ventromedial nucleus of the hypothalamus (VMH) and organum vasculosum of the lamina terminalis (OVLT) than control females. Fos-IR cells in the preoptic area (POA) were only greater than in control females after 6 h exposure to a male. Removal of males decreased the number of Fos-IR cells in the ARC, VMH and OVLT, but not in the POA. Thus, hypothalamic neural activation and LH secretion in female sheep are stimulated by males and decline after male removal. However, activation in the POA persists after removal and may explain the incomplete decline in the LH response.
KW - fertility
KW - hypothalamus
KW - neuroendocrinology
KW - pheromone
KW - reproduction
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U2 - 10.1071/RD19079
DO - 10.1071/RD19079
M3 - Article
C2 - 31511142
AN - SCOPUS:85072256212
SN - 1031-3613
VL - 31
SP - 1674
EP - 1681
JO - Reproduction, Fertility and Development
JF - Reproduction, Fertility and Development
ER -