Augmentation of the LH Surge By Male Olfactory Signals Is Associated with Avpv Kiss1 Cell Activation in Female Rats

Presentation Number: SUN 476
Date of Presentation: April 2nd, 2017

Youki Watanabe*1, Ren Ishigaki1, Kana Ikegami1, Nahoko Ieda1, Yoshihisa Uenoyama1, Kei-ichiro Maeda2, Hiroko Tsukamura1 and Naoko Inoue1
1Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan, 2Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan

Abstract

Olfactory signals exert influences on reproductive function in mammals. The present study aims to determine if the olfactory signals derived from male rats stimulate kisspeptin and GnRH neuronal activities, and consequently LH secretion in female rats. Wistar-Imamichi strain female rats were ovariectomized (OVX) and implanted with a Silastic tube containing preovulatory levels of estradiol-17β (E2). The female rats were sacrificed 1 hour after the exposure to either clean bedding, female-soiled bedding or male-soiled bedding. Dual visualization of Kiss1 mRNA by in situ hybridization (ISH) and c-Fos by immunohistochemistry revealed that the number of c-Fos-positive Kiss1-expressing cells in the anteroventral periventricular nucleus (AVPV) was significantly higher in female rats exposed to male-soiled bedding than in the other groups. On the other hand, the c-Fos-positive Kiss1-expressing cells were scarcely detected in the arcuate nucleus (ARC) of females in all groups. Dual staining of Gnrh1 mRNA and c-Fos showed that the number of c-Fos-positive Gnrh1-expressing cells in the hypothalamus was comparable between groups. The number of c-Fos-positive cells in female rats exposed to male-soiled bedding was significantly higher than the other two groups in the following brain regions where the vomeronasal and main olfactory signals are relayed: the posterior division of bed nucleus of the stria terminalis, the cortical amygdala and the medial part of the amygdala. The peak of the LH surge and area under the curve of LH concentrations in the rats exposed to male-soiled bedding were significantly higher than those of the other two groups. These results suggest that olfactory signals derived from male rats activate AVPV kisspeptin neurons, resulting in augmentation of the peak of the LH surge in female rats. Taken together, the present study indicates that olfactory signals derived from male rats stimulate AVPV kisspeptin neurons and consequently enhance LH surge in female rats. This mechanism may ensure successful ovulation in female rats under the presence of male rats.

 

Nothing to Disclose: YW, RI, KI, NI, YU, KIM, HT, NI