Central Orexin A Affects Reproductive Axis by Modulation of Hypothalamic Kisspeptin/Neurokinin B/Dynorphin Secreting Neurons in the Male Wistar Rats.
It is an established fact that orexin plays an important role in regulating the reproductive axis and the secretions of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH). However, its precise cellular and molecular mechanisms are not fully recognized. Accordingly, the aim of the present study is to find out whether the central injection of orexin A (OXA) and its antagonists, SB-334867 (as orexin receptor antagonist 1; OX1RA) and JNJ-10397049 (as orexin receptor antagonist 2; OX2RA), either alone or in combination, can leave any impact on the reproductive axis (either hormonal or behavioral) in the male Wistar rats. Furthermore, in order to see whether OXA signals can be relayed through the pathway of kisspeptin/neurokinin B/dynorphin (known as KNDy neurons, a neural network which works upstream of GnRH neurons) or not, the relative gene expression of these neuropeptides were measured. Overall, the data from radioimmunoassay revealed that OXA significantly decreases the mean serum level of LH and testosterone and, in a similar vein, its antagonists neutralize this impact. Moreover, data from real-time quantitative PCR indicated that OXA has significantly reduced the hypothalamic expression of Gnrh. In this line, the gene expressions of Kisspeptin and Neurokinin b decreased. However, OXA antagonists neutralize this impact. Also, the expression of Dynorphin gene was upregulated by the following application of the OXA. The results of this study are related to the impact of orexin on the reproductive axis. It is recommended that KNDy neurons as the interneural pathway relay the information of orexin to the GnRH neurons.
['Hosseini|Abdolkarim|A|', 'Khazali|Homayoun|H|']
D000818:Animals D001583:Benzoxazoles D004146:Dioxanes D004399:Dynorphins D005786:Gene Expression Regulation D007987:Gonadotropin-Releasing Hormone D007031:Hypothalamus D007276:Injections, Intraventricular D059648:Kisspeptins D007986:Luteinizing Hormone D008297:Male D009287:Naphthyridines D015287:Neurokinin B D009474:Neurons D000068797:Orexins D010671:Phenylurea Compounds D011897:Random Allocation D051381:Rats D017208:Rats, Wistar D060888:Real-Time Polymerase Chain Reaction D012098:Reproduction D012726:Sexual Behavior, Animal D013739:Testosterone D014508:Urea
Orexin Kisspeptin Gonadotropin-releasing hormone KNDy neurons Luteinizing hormone