Distinct dynorphin expression patterns with low- and high-dose estrogen treatment in the arcuate nucleus of female rats

Moeko Kanaya
Kinuyo Iwata
Hitoshi Ozawa

Kisspeptin (KISS1; encoded by Kiss1) neurons in the arcuate nucleus (ARC) coexpress tachykinin 3 (TAC3; also known as neurokinin B) and dynorphin A (PDYN). Accordingly
 they are termed KNDy neurons and considered to be crucial in generating pulsatile release of gonadotropin-releasing hormone. Accumulating evidence suggests that Kiss1 and Tac3 are negatively regulated by estrogen. However
 it has not been fully determined whether and how estrogen modulates Pdyn and PDYN. Here
 we examined the expression of Pdyn mRNA and PDYN by in situ hybridization and immunohistochemistry
 respectively
 in the ARC of female rats after ovariectomy (OVX) and OVX plus low-or high-dose beta-estradiol (E-2) replacement. We also investigated the effect of E-2 on expression of Kiss1
 KISS1
 Tac3
 and TAC3. Furthermore
 colocalization of PDYN and estrogen receptor alpha (ESR1) was determined. Subsequently
 we found that low-dose E-2 treatment had no effect on Pdyn mRNA-expressing cells
 but increased PDYN-immunoreactive (ir) cell numbers. In contrast
 high-dose E-2 treatment resulted in prominent reductions in both Pdyn mRNA-expressing and PDYN-ir cell numbers. Changes induced by low or high doses of E-2 were similarly observed in the expression of Kiss1
 KISS1
 Tac3
 and TAC3. The majority of PDYN-ir neurons coexpressed ESR1 in all groups. Our results indicate that E-2 regulates the expression of PDYN
 as well as KISS1 and TAC3
 with regulation by E-2 differing according to its levels.Summary SentenceEstrogen regulates dynorphin expression in the arcuate nucleus of female rats with low-dose estrogen suppressing dynorphin release and high-dose estrogen inhibiting dynorphin mRNA expression.

BIOLOGY OF REPRODUCTION

OXFORD UNIV PRESS INC

97

5

10.1093/biolre/iox131

https://doi.org/10.1093/biolre/iox131
https://www.ncbi.nlm.nih.gov/pubmed/29069289
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000418963100006&DestApp=WOS_CPL