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Effects of intravenous administration of neurokinin receptor subtype-selective agonists on gonadotropin-releasing hormone pulse generator activity and luteinizing hormone secretion in goats.
- Source :
-
The Journal of reproduction and development [J Reprod Dev] 2015; Vol. 61 (1), pp. 20-9. Date of Electronic Publication: 2014 Oct 27. - Publication Year :
- 2015
-
Abstract
- Recent evidence suggests that neurokinin B (NKB), a member of the neurokinin (tachykinin) peptide family, plays a pivotal role in gonadotropin-releasing hormone (GnRH) pulse generation. Three types of neurokinin receptors (NKRs), NK1R, NK2R and NK3R, are found in the brain. Although NKB preferentially binds to NK3R, other NKRs are possibly also involved in NKB action. The present study examined the effects of intravenous administration of the NKR subtype-selective agonists GR73632 (NK1R), GR64349 (NK2R), and senktide (NK3R) on GnRH pulse generator activity and luteinizing hormone (LH) secretion. Multiple-unit activity (MUA) was monitored in ovariectomized goats (n = 5) implanted with recording electrodes. Characteristic increases in MUA (MUA volleys) were considered GnRH pulse generator activity. Although three NKR agonists dose-dependently induced an MUA volley and an accompanying increase in LH secretion, the efficacy in inducing the volley markedly differed. As little as 10 nmol of senktide induced an MUA volley in all goats, whereas a dose of 1000 nmol was only effective for the NK1R and NK2R agonists in two and four goats, respectively. When the treatment failed to evoke an MUA volley, no apparent change was observed in the MUA or LH secretion. Similar effects of the NK2R and NK3R agonists were observed in the presence of estradiol. The results demonstrated that NK3R plays a predominant role in GnRH pulse generation and suggested that the contributions of NK1R and NK2R to this mechanism may be few, if any, in goats.
- Subjects :
- Animals
Estradiol chemistry
Female
Goats
Infusions, Intravenous
Kisspeptins metabolism
Ligands
Luteinizing Hormone metabolism
Neurokinin A administration & dosage
Neurokinin A analogs & derivatives
Peptide Fragments administration & dosage
Receptors, Neurokinin-1 metabolism
Receptors, Neurokinin-2 metabolism
Receptors, Neurokinin-3 metabolism
Signal Transduction
Substance P administration & dosage
Substance P analogs & derivatives
Time Factors
Gonadotropin-Releasing Hormone metabolism
Receptors, Neurokinin-1 agonists
Receptors, Neurokinin-2 agonists
Receptors, Neurokinin-3 agonists
Subjects
Details
- Language :
- English
- ISSN :
- 1348-4400
- Volume :
- 61
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- The Journal of reproduction and development
- Publication Type :
- Academic Journal
- Accession number :
- 25345909
- Full Text :
- https://doi.org/10.1262/jrd.2014-109