Effect of orexin-A on prolactin secretion in lambs born under different photoperiod conditions – in vitro study
E. Molik, M. Błasiak, T. Misztal, K. Romanowicz, D.A. Zięba-Przybylskahttps://doi.org/10.17221/7909-CJASCitation:Molik E., Błasiak M., Misztal T., Romanowicz K., Zięba-Przybylska D.A. (2015): Effect of orexin-A on prolactin secretion in lambs born under different photoperiod conditions – in vitro study. Czech J. Anim. Sci., 60: 33-37.
The role of orexin-A in the regulation of prolactin secretion in lambs born in different photoperiods was determined. The experiment was conducted with 30 female lambs. Pituitary glands were collected from 40-day-old lambs in three different seasons (n = 10 per each season) and photoperiods (light (L) hours to darkness (D) hours): long (May – L 14 : D 10), intermediate (August – L 13 : D 11), and short (December – L 10 : D 14). At 40 days of age, the lambs were decapitated, and their pituitaries were dissected and cut in half along the longitudinal fissure so that each half contained both glandular and nervous parts. The in vitro incubation of the glands was performed for 3 h in Parker’s medium at 37°C. In each season, the control pituitary glands (K1, K2, K3) were incubated in Parker’s medium, while the experimental pituitary glands (Ox1, Ox2, Ox3) were incubated in medium containing 1000 ng/ml of exogenous orexin. The administration of orexin-A during the long photoperiod (May) caused a significant (P ≤ 0.01) increase in prolactin secretion during the first hour of incubation (Ox1: 47.56 ± 8.4 ng/ml vs K1: 36.08 ± 7.8 ng/ml). During the intermediate photoperiod (August), a significantly (P ≤ 0.01) higher concentration of prolactin was observed in the first hour of incubation in the Ox2 group than in the control group (K2). During the first hour of incubation in December, the prolactin concentrations were significantly (P ≤ 0.01) higher in the Ox3 group than in the K3 group. Orexin-A increased prolactin secretion from pituitary explants collected from lambs born under all investigated time-points. The study results indicate that orexin-A is a stimulatory factor of prolactin secretion in sheep.Keywords:seasonality sheep; incubation; pituitary glandReferences:
Archer Zoe A, Findlay Patricia A, Rhind Stewart M, Mercer Julian G, Adam Clare L (2002): Orexin gene expression and regulation by photoperiod in the sheep hypothalamus. Regulatory Peptides, 104, 41-45 https://doi.org/10.1016/S0167-0115(01)00347-0Hasiec Małgorzata, Herman Andrzej P., Molik Edyta, Dobek Elżbieta, Romanowicz Katarzyna, Fülöp Ferenc, Misztal Tomasz (2012): The stimulatory effect of salsolinol on prolactin gene expression within the anterior pituitary of lactating sheep: In vivo and in vitro study. Small Ruminant Research, 102, 202-207 https://doi.org/10.1016/j.smallrumres.2011.07.011HOOLEY R. D., CAMPBELL J. J., FINDLAY J. K. (1978): THE IMPORTANCE OF PROLACTIN FOR LACTATION IN THE EWE. Journal of Endocrinology, 79, 301-310 https://doi.org/10.1677/joe.0.0790301Iqbal J, Henry B.A, Pompolo S, Rao A, Clarke I.J (2003): Long-term alteration in bodyweight and food restriction does not affect the gene expression of either preproorexin or prodynorphin in the sheep. Neuroscience, 118, 217-226 https://doi.org/10.1016/S0306-4522(02)00815-1Kokot F., Stupnicki R. (1985): Radioimmunoassay and Radiocompetency Methods Used in the Clinic. PZWL, Warsaw, Poland. (in Polish)Lincoln G.A. (2000): Role of the Pituitary Gland in the Development of Photorefractoriness and Generation of Long-Term Changes in Prolactin Secretion in Rams. Biology of Reproduction, 62, 432-438 https://doi.org/10.1095/biolreprod62.2.432Martynska L., Wolinska Witort E., Chmielowska M., Bik W., Baranowska B. (2006): Effect of orexin A on prolactin secretion from the pituitary cells in the immature female rats in conditions of primary culture. Conference Materials, 3rd Workshop PTN, 78. (in Polish)Molik E., Misztal T., Romanowicz K., Wierzchos E. (2006): The influence of length day on melatonin secretion during lactation in asesonal sheep. Archive für Tierzucht, 49, 359–364.Molik Edyta, Misztal Tomasz, Romanowicz Katarzyna, Wierzchoś Edward (2007): Dependence of the lactation duration and efficiency on the season of lambing in relation to the prolactin and melatonin secretion in ewes. Livestock Science, 107, 220-226 https://doi.org/10.1016/j.livsci.2006.09.013Molik E., Zieba D.A, Misztal T., Romanowicz K., Wszola M., Wierzchos E., Nowakowski M. (2008): The role of orexin A in the control of prolactin and growth hormone secretions in sheep – in vitro study. Journal of Physiology and Pharmacology, 59, 91–100.Molik E., Misztal T., Romanowicz K., Zieba D., Wierzchos E. (2009): Changes in growth hormone and prolactin secretion in ewes used for milk under different photoperiodic conditions. Bulletin of Veterinary Institute in Pulawy, 53, 389–393.Molik E., Misztal T., Romanowicz K., Zieba-Przybylska D. (2011): Influence of orexin A on prolactin and growth hormone secretion in lactation sheep – in vitro study. Conference Materials, 6th Workshop TBR, 48. (in Polish)Peaker M., Neville M.C. (1991): Hormones in milk: chemical signals to the offspring? Journal of Endocrinology, 131, 1–3.Reksen O., Tverdal A., Landsverk K., Kommisrud E., Bøe K.E., Ropstad E. (1999): Effects of Photointensity and Photoperiod on Milk Yield and Reproductive Performance of Norwegian Red Cattle. Journal of Dairy Science, 82, 810-816 https://doi.org/10.3168/jds.S0022-0302(99)75300-2Russell S. H., Kim M. S., Small C. J., Abbott C. R., Morgan D. G. A., Taheri S., Murphy K. G., Todd J. F., Ghatei M. A., Bloom S. R. (2000): Central Administration of Orexin A Suppresses Basal and Domperidone Stimulated Plasma Prolactin. Journal of Neuroendocrinology, 12, 1213-1218 https://doi.org/10.1046/j.1365-2826.2000.00582.xSakurai Takeshi, Amemiya Akira, Ishii Makoto, Matsuzaki Ichiyo, Chemelli Richard M, Tanaka Hirokazu, Williams S.Clay, Richardson James A, Kozlowski Gerald P, Wilson Shelagh, Arch Jonathan R.S, Buckingham Robin E, Haynes Andrea C, Carr Steven A, Annan Roland S, McNulty Dean E, Liu Wu-Schyong, Terrett Jonathan A, Elshourbagy Nabil A, Bergsma Derk J, Yanagisawa Masashi (1998): Orexins and Orexin Receptors: A Family of Hypothalamic Neuropeptides and G Protein-Coupled Receptors that Regulate Feeding Behavior. Cell, 92, 573-585 https://doi.org/10.1016/S0092-8674(00)80949-6Sakurai T., Moriguchi T., Furuya K., Kajiwara N., Nakamura T., Yanagisawa M., Goto K. (): Structure and Function of Human Prepro-orexin Gene. Journal of Biological Chemistry, 274, 17771-17776 https://doi.org/10.1074/jbc.274.25.17771Schams D., Russe I., Schallenberger E., Prokopp S., Chant J. S. D. (1984): The role of steroid hormones, prolactin and placental lactogen on mammary gland development in ewes and heifers. Journal of Endocrinology, 102, 121-NP https://doi.org/10.1677/joe.0.1020121Shiu R P C, Friesen H G (1980): Mechanism of Action of Prolactin in the Control of Mammary Gland Function. Annual Review of Physiology, 42, 83-96 https://doi.org/10.1146/annurev.ph.42.030180.000503