Lesions of KNDy and Kiss1R neurons in the arcuate nucleus produce different effects on LH pulse patterns in female sheep

This study tested the functional role of ovine KNDy neurons in pulse generation and explored the roles of nearby Kiss1 receptor (Kiss1R)-containing cells using lesions produced with saporin (SAP) conjugates. Injection of NK3-SAP ablated over 90% of the KNDy cells, while Kiss-SAP (saporin conjugated to kisspeptin-54) lesioned about two-thirds of the Kiss1R population without affecting KNDy or GnRH cell number. Both lesions produced a dramatic decrease in LH pulse amplitude, but had different effects on LH pulse patterns. NK3-SAP increased interpulse interval (IPI), but Kiss-SAP did not. In contrast, Kiss-SAP disrupted the regular hourly occurrence of LH pulses, but NK3-SAP did not. Since Kiss1R is not expressed in KNDy cells, HiPlex RNAScope was used to assess the co-localization of eight neurotransmitters and three receptors in ARC Kiss1R-containing cells. Kiss1R cells primarily contained transcript markers for GABA (68%), glutamate (28%), ESR1 (estrogen receptor-α) mRNA, and OPRK1 (kappa opioid receptor) mRNA. These data support the conclusion that KNDy neurons are essential for GnRH pulses in ewes, while ARC Kiss1R cells are not, but do maintain the amplitude and regularity of GnRH pulses. We thus propose that in sheep ARC Kiss1R neurons form part of a positive feedback circuit that reinforces the activity of the KNDy neural network, with GABA or glutamate likely being involved.PMID:37776515 | DOI:10.1210/endocr/bqad148
Source: Endocrinology - Category: Endocrinology Authors: Source Type: research