Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The gonadotropin-releasing hormone (GnRH) pulse and surge are considered to be generated by arcuate kisspeptin/neurokinin B/dynorphin A (KNDy) neurons and anteroventral periventricular nucleus (AVPV) kisspeptin neurons, respectively, in female rodents. The majority of KNDy and AVPV kisspeptin neurons express κ-opioid receptors (KORs, encoded by Oprk1) in female rodents. Thus, this study aimed to investigate the effect of a conditional Oprk1-dependent Kiss1 deletion in kisspeptin neurons on the luteinizing hormone (LH) pulse/surge and fertility using Kiss1-floxed/Oprk1-Cre rats, in which Kiss1 was deleted in cells expressing or once expressed the Oprk1/Cre. The Kiss1-floxed/Oprk1-Cre female rats, with Kiss1 deleted in a majority of KNDy neurons, showed normal puberty while having a one-day longer estrous cycle and fewer pups than Kiss1-floxed controls. Notably, ovariectomized (OVX) Kiss1-floxed/Oprk1-Cre rats showed profound disruption of LH pulses in the presence of a diestrous level of estrogen but showed apparent LH pulses without estrogen treatment. Furthermore, Kiss1-floxed/Oprk1-Cre rats, with Kiss1 deleted in approximately half of AVPV kisspeptin neurons, showed a lower peak of the estrogen-induced LH surge than controls. These results suggest that arcuate and AVPV kisspeptin neurons expressing or having expressed Oprk1 have a role in maintaining normal GnRH pulse and surge generation, the normal length of the estrous cycle, and the normal offspring number in female rats.

DOI： 10.1038/s41598-023-47222-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Animal Reproduction  

DOI： 10.1262/jrd.2023-019

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Language：English   Publishing type：Research paper (scientific journal)  

Reproductive function is suppressed during lactation owing to the suckling-induced suppression of the kisspeptin gene (Kiss1) expression in the arcuate nucleus (ARC) and subsequent suppression of luteinizing hormone (LH) release. Our previous study revealed that somatostatin (SST) neurons mediate suckling-induced suppression of LH release via SST receptor 2 (SSTR2) in ovariectomized lactating rats during early lactation. This study examined whether central SST-SSTR2 signaling mediates the inhibition of ARC Kiss1 expression and LH release in lactating rats during late lactation and whether the inhibition of glutamatergic neurons, stimulators of LH release, is involved in the suppression of LH release mediated by central SST-SSTR2 signaling in lactating rats. A central injection of the SSTR2 antagonist CYN154806 (CYN) significantly increased ARC Kiss1 expression in lactating rats on day 16 of lactation. Dual in situ hybridization revealed that few ARC Kiss1-positive cells co-expressed Sstr2, and some of the ARC Slc17a6 (a glutamatergic neuronal marker)-positive cells co-expressed Sstr2. Furthermore, almost all ARC Kiss1-positive cells co-expressed Grin1, a subunit of N-methyl-D-aspartate (NMDA) receptors. The numbers of Slc17a6/Sstr2 double-labeled and Slc17a6 single-labeled cells were significantly lower in lactating dams than in non-lactating rats whose pups had been removed after parturition. A central injection of an NMDA antagonist reversed the CYN-induced increase in LH release in lactating rats. Overall, these results suggest that central SST-SSTR2 signaling, at least partly, mediates the suppression of ARC Kiss1 expression and LH release by inhibiting ARC glutamatergic interneurons in lactating rats.

DOI： 10.1262/jrd.2022-009

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Gene editing in mammalian zygotes enables us to generate genetically modified animals rapidly and efficiently. In this study, we compare multiple gene targeting strategies in rat zygotes by generating a novel knock-in reporter rat line to visualize the expression pattern of transcription factor AP-2 gamma (Tfap2c). The targeting vector is designed to replace the stop codon of Tfap2c with T2A-tdTomato sequence. We show that the combination of electroporation-mediated transduction of CRISPR/Cas9 components with adeno-associated virus-mediated transduction of the targeting vector is the most efficient in generating the targeted rat line. The Tfap2c-T2A-tdTomato fluorescence reflects the endogenous expression pattern of Tfap2c in preimplantation embryo, germline, placenta, and forebrain during rat embryo development. The reporter line generated here will be a reliable resource for identifying and purifying Tfap2c expressing cells in rats, and the gene targeting strategy we used can be widely applied for generating desired animals.

DOI： 10.1002/mrd.23562

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Language：English   Publishing type：Research paper (scientific journal)  

Endogenous opioid peptides have attracted attention as critical neuropeptides in the central mechanism regulating female reproduction ever since the discovery that arcuate dynorphin neurons that coexpress kisspeptin and neurokinin B (NKB), which are also known as kisspeptin/neurokinin B/dynorphin (KNDy) neurons, play a role as a master regulator of pulsatile gonadotropin-releasing hormone (GnRH) release in mammals. In this study, we first focus on the role of dynorphin released by KNDy neurons in the GnRH pulse generation. Second, we provide a historical overview of studies on endogenous opioid peptides. Third, we discuss how endogenous opioid peptides modulate tonic GnRH/gonadotropin release in female mammals as a mediator of inhibitory internal and external cues, such as ovarian steroids, nutritional status, or stress, on reproduction. Then, we discuss the role of endogenous opioid peptides in GnRH surge generation in female mammals.

DOI： 10.3389/fnins.2022.958377

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J-GLOBAL

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J-GLOBAL

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Event date： 2023.10.27 - 2023.10.28

Presentation type：Oral presentation (general)  

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Event date： 2023.9.24 - 2023.9.27

Presentation type：Oral presentation (general)  

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Event date： 2023.6.1 - 2023.6.3

Presentation type：Oral presentation (general)  

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Event date： 2022.10.28 - 2022.10.30

Presentation type：Oral presentation (general)  

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Event date： 2022.9.11 - 2022.9.14

Presentation type：Poster presentation  

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