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Evidence that synaptic plasticity of glutamatergic inputs onto KNDy neurones during the ovine follicular phase is dependent on increasing levels of oestradiol.
- Source :
-
Journal of neuroendocrinology [J Neuroendocrinol] 2021 Mar; Vol. 33 (3), pp. e12945. - Publication Year :
- 2021
-
Abstract
- Neurones in the arcuate nucleus co-expressing kisspeptin, neurokinin B (NKB) and dynorphin (KNDy) play a critical role in the control of gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH) secretion. In sheep, KNDy neurones mediate both steroid-negative- and -positive-feedback during pulsatile and preovulatory surge secretions of GnRH/LH, respectively. In addition, KNDy neurones receive glutamatergic inputs expressing vGlut2, a glutamate transporter that serves as a marker for those terminals, from both KNDy neurones and other populations of glutamatergic neurones. Previous work reported higher numbers of vGlut2-positive axonal inputs onto KNDy neurones during the LH surge than in luteal phase ewes. In the present study, we further examined the effects of the ovarian steroids progesterone (P) and oestradiol (E <subscript>2</subscript> ) on glutamatergic inputs to KNDy neurones. Ovariectomised (OVX) ewes received either no further treatment (OVX) or steroid treatments that mimicked the luteal phase (low E <subscript>2</subscript>  + P), and early (low E <subscript>2</subscript> ) or late follicular (high E <subscript>2</subscript> ) phases of the oestrous cycle (n = 4 or 5 per group). Brain sections were processed for triple-label immunofluorescent detection of NKB/vGlut2/synaptophysin and analysed using confocal microscopy. We found higher numbers of vGlut2 inputs onto KNDy neurones in high E <subscript>2</subscript> compared to the other three treatment groups. These results suggest that synaptic plasticity of glutamatergic inputs onto KNDy neurones during the ovine follicular phase depend on increasing levels of E <subscript>2</subscript> required for the preovulatory GnRH/surge. These synaptic changes likely contribute to the positive-feedback action of oestrogen on GnRH/LH secretion and thus the generation of the preovulatory surge in the sheep.<br /> (© 2021 British Society for Neuroendocrinology.)
- Subjects :
- Animals
Estradiol metabolism
Female
Gonadotropin-Releasing Hormone blood
Luteal Phase drug effects
Luteinizing Hormone blood
Ovariectomy
Sheep
Vesicular Glutamate Transport Protein 2 metabolism
Dynorphins physiology
Estradiol physiology
Follicular Phase physiology
Glutamates physiology
Kisspeptins physiology
Neurokinin B physiology
Neuronal Plasticity physiology
Synapses physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1365-2826
- Volume :
- 33
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Journal of neuroendocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 33713519
- Full Text :
- https://doi.org/10.1111/jne.12945