Photoperiod regulates the differential expression of KiSS-1 and GPR54 in various tissues and sexes of striped hamster

Abstract

ABSTRACT. In order to investigate how photoperiod affects the expression of KiSS-1/G-protein-coupled receptor 54 (GPR54), the hypothalamus, the ovaries and testicles of the striped hamster were studied following photoperiod treatment and melatonin injection. We found that the melatonin concentration in the blood of the striped hamster was consistent with the treated photoperiods and that the photoperiod had significant effects on KiSS-1 expression, but the effect of photoperiod on GPR54 expression differed among tissues and sexes. The relative expression of KiSS-1 in the gonads of the male and female striped hamster was significantly higher than that in the hypothalamus, while the difference in GPR54 between the gonads and hypothalamus was inconsistent between the male and female striped hamster. In the striped hamster injected with melatonin, the expression level of KiSS-1 in the gonads and hypothalamus of the male and female striped hamster was significantly decreased; the expression level of GnRH in the gonads was also significantly decreased; the expression of GPR54 in the hypothalamus was increased. In the hypothalamus, a significant positive correlation existed between KiSS-1 and GnRH expression, while a negative correlation was observed between 13895 Photoperiod regulates expression of KiSS-1 and GPR54 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (4): 13894-13905 (2015) GPR54 and GnRH expression. These results suggest that the photoperiodmelatonin-KiSS-1-GnRH pathway plays an important role in the seasonal reproduction mechanism of the striped hamster. Additionally, photoperiod or melatonin may not be a direct regulatory factor of GPR54 expression.

Kisspeptin and RFRP3 modulate body mass in Phodopus sungorus via two different neuroendocrine pathways

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“…The results clearly demonstrated that the large production of melatonin in SD inhibits ARC Kiss1 expression, this effect being further modulated by the negative sex steroid feedback, whereas the melatonin‐driven change in AVPV Kiss1 only depends on the positive sex steroid feedback. A similar inhibitory effect of melatonin on Kp expression was also reported in the Turkish (Piekarski et al., ) and striped (Li et al., ) hamster and even in the rat (de Oliveira et al., ). Although a direct effect of melatonin on Kp expression in a hypothalamic cell line has been reported (Gingerich et al., ), in vivo studies have demonstrated that ARC Kp neurons do not express MT1 (Li, Rao, Pereira, Clarke, & Smith, ).…”

Effects of Melatonin on Anterior Pituitary Plasticity: A Comparison Between Mammals and Teleosts

“…For instance, using a combination of photoperiod manipulation, pinealectomy and melatonin administration Revel and colleagues ( 50 ) and Ansel and colleagues ( 51 ) demonstrated that melatonin clearly reduces ARC KISS1 mRNA in Syrian hamsters, an effect further modulated by the negative steroid feedback. Similar inhibitory effects of melatonin on KISS1 mRNA were detected in Turkish ( Mesocricetus brandti ) ( 52 ) and striped ( Cricetulus barabensis ) ( 53 ) hamsters but also in the rat, a non-seasonal breeder ( 54 ). Interestingly, in the Siberian hamster, ARC KISS1 mRNA levels are lower under LP due to a robust negative sex steroid feedback overriding the melatonin signal, since castration in LP animals restores high KISS1 mRNA levels ( 79 ).…”