Location: Reproduction ResearchTitle: Effect of progesterone on kisspeptin and neurokinin B cell numbers in the arcuate nucleus of the female pig Author
|Cushman, Robert - Bob|
Submitted to: Journal of Neuroscience
Publication Type: Abstract Only
Publication Acceptance Date: 11/10/2013
Publication Date: 11/10/2013
Citation: Hileman, S.M., Meadows, L.J., Porter, K.L., Coolen, L.M., Fergani, C., Rempel, L.A., Cushman, R.A., Oliver, W.T., Wright, E.C., Miles, J.R., Lents, C.A. 2013. Effect of progesterone on kisspeptin and neurokinin B cell numbers in the arcuate nucleus of the female pig [abstract]. Abstracts of Society for Neuroscience Annual Meeting, November 9-13, 2013, San Diego, California. Poster # BBB25. Available: http://www.sfn.org/annual-meeting/past-and-future-annual-meetings. Interpretive Summary:
Technical Abstract: Progesterone acts at the hypothalamus to inhibit LH secretion in the pig, but the mechanism for this is unknown. Kisspeptin and neurokinin B (NKB) have both been shown to influence GnRH/LH secretion and mediate steroid negative feedback in several species and to be critical for normal reproductive function in humans. This study examines the influence of progesterone on kisspeptin and NKB expression in the pig and their potential colocalization in neurons of the arcuate nucleus of the hypothalamus (ARC). The hypothesis was tested that progesterone would reduce LH secretion in association with a decrease in ARC kisspeptin or NKB cell number. White crossbred, postpubertal gilts (106 ± 1.5 kg) were surgically fitted with an indwelling jugular catheter and either ovariectomized (OVX; n=3) or ovariectomized and treated with progestin (Altrenogest, 15 mg/d; OVX+P; n=4) for 10 days beginning 2 to 3 weeks after OVX. Blood samples were collected at 12 min intervals for 4.6 hours on day 9 of treatment. On day 10 of treatment, gilts were euthanized and brain tissue collected for immunocytochemical analysis of kisspeptin and NKB expression across five or three sections, respectively, of the caudal ARC. Progesterone treatment significantly (p<0.05) reduced mean LH (OVX, 1.58 ± 0.20 ng/ml; OVX+P, 0.70 ± 0.23 ng/ml) and LH interpulse interval (OVX, 43.5 ± 5.1 min; OVX+P, 184.5 ± 44.7 min) without significantly affecting LH pulse amplitude. Contrary to our hypothesis, kisspeptin cell numbers were increased (p<0.05) in progesterone-treated gilts (OVX, 334.7 ± 26.5 cells; OVX+P, 446.5 ± 47.5 cells). A similar trend was noted for NKB cell numbers, but this difference was not significant (p>0.20). Dual immunofluorescence revealed that kisspeptin and NKB were highly colocalized in the ARC. These data indicate that if kisspeptin or NKB are involved in the suppression of LH secretion by progesterone in the pig, it is due most likely to a decrease in release of these neuropeptides and not a decrease in kisspeptin or NKB protein expression.