title: Acute regulation of plasma insulin-like peptide 3 concentrations by luteinizing hormone in male goats.
abstract: Recently, it was reported that in bulls secretion of insulin-like peptide 3 (INSL3) in blood occurred in a pulsatile manner and was acutely regulated by LH. In the present study, the acute regulation of plasma INSL3 and its temporal relationships with LH and testosterone were examined in six sexually matured male goats using the following experimental design. (1) After stimulating LH release by administering a GnRH analogue, blood levels of LH, INSL3, and testosterone were monitored at 15-minute intervals for 2 hours followed by hourly intervals up to 8 hours. (2) After activation of the LH receptor by hCG blood levels of INSL3 and testosterone were determine at 15-minute intervals for 2 hours, followed by hourly intervals up to 8 hours, daily intervals up to Day 8, and finally on Day 12. (3) The release of LH, INSL3, and testosterone in normal physiology was established at 15-minute intervals for an 8-hour session. Concentrations of LH, INSL3, and testosterone in plasma were measured by enzyme-immunoassays. After GnRH treatment, mean plasma concentrations of all three hormones increased (P < 0.05) dramatically from 30 minutes and remained high until 120 minutes (LH), 75 minutes (INSL3), and 4 hours (testosterone) after treatment. After hCG treatment, mean plasma INSL3 concentrations increased (P < 0.05) from 30 minutes and remained elevated until the end of sampling on Day 12. An increase (P < 0.05) in mean plasma testosterone concentrations occurred from 15 minutes and remained high until Day 6. The mean increase (maximum per pretreatment concentration) of INSL3 concentrations after administration of GnRH and hCG was lower (P < 0.01) than that of testosterone. The secretory pattern of LH, INSL3, and testosterone in the general circulation was pulsatile with a frequency of 5.5 ± 0.6, 4.7 ± 0.5, and 2.2 ± 0.5, respectively, during the 8-hour period. Twenty out of 28 (71%) of these INSL3 pulses peaked within 1 hour after a peak of an LH pulse. The mean increase (peak per basal concentration) of INSL3 pulses (2.1 ± 0.1 fold, n = 28) was lower (P < 0.01) than that of testosterone pulses (4.3 ± 2.2 fold, n = 13). In conclusion, secretion of INSL3 in blood occurred, like in bulls, in a pulsatile manner soon after LH pulses in male goats. The absolute concentrations of INSL3 in male goats were higher than that reported in other mammals. Insulin-like peptide 3 concentrations were acutely increased by endogenous and exogenous LH in male goats, but the rise of INSL3 was lower than that of testosterone.
authors.affiliation: Department of Advanced Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan.
authors.forename: M A
authors.initials: MA
authors.lastname: Hannan
authors.affiliation: Department of Advanced Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan. Electronic address: nkawate@vet.osakafu-u.ac.jp.
authors.forename: N
authors.initials: N
authors.lastname: Kawate
authors.affiliation: Department of Advanced Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Fukami
authors.affiliation: Department of Animal Science, Faculty of Agriculture, University of Ruhuna, Kamburupitiya, Sri Lanka.
authors.forename: I N
authors.initials: IN
authors.lastname: Pathirana
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Büllesbach
authors.affiliation: Department of Advanced Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Inaba
authors.affiliation: Department of Advanced Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tamada
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000502:physiology; D006041:Goats / Q000097:blood / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008297:Male; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D013739:Testosterone / Q000097:blood
chemical_list: D006063:Chorionic Gonadotropin; D007328:Insulin; C084797:Leydig insulin-like protein; D011506:Proteins; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; C009936:fertirelin
keywords: GnRH; INSL3; LH; Male goat; Testosterone; hCG