Reproduction Abstracts

In photoperiodic species, remodelling of pituitary microvasculature appears to play a key role in the regulation of the annual reproductive cycle. Recent studies have revealed seasonal changes in the vascular loops of the ovine pituitary stalk. Microvasculature remodelling is under the control of pro-angiogenic (VEGF165a) and anti-angiogenic (VEGF165b) isoforms of vascular endothelial growth factor (VEGF). Here, we examined the differential expression of ...

In photoperiodic species, the pattern of pineal melatonin secretion translates the effects of day length on the annual reproductive cycle. Continuous delivery of exogenous melatonin to sheep during the non-breeding season is known to activate the gonadotrophic axis, and to suppress prolactin secretion through a mechanism involving the pars tuberalis (PT) of the pituitary gland. Recent studies have revealed that vascular endothelial growth factor (VEGF), a major regulator of an...

Recent studies have shown that microvasculature remodelling of the ovine pituitary gland is seasonally regulated through mechanisms involving the differential expression of pro-angiogenic (VEGF165) and anti-angiogenic (VEGF165b) isoforms of vascular endothelial growth factor (VEGF). As for other photoperiodic species, the pattern of pineal melatonin secretion mediates the effects of day length on the sheep seasonal reproductive cycle. In this study, we in...

The pars tuberalis (PT) of the ovine pituitary contains high-density melatonin receptors (MT1) known to participate in the seasonal regulation of prolactin (PRL) output from lactotroph cells in the pars distalis (PD). However, the paracrine mechanism relaying the signal from the PT to the PD remains unresolved. We have recently shown that MT1-positive cells in the PT co-express vascular endothelial growth factor-A isoforms (VEGF165/VEGF165b), and that VEG...