Treatment of lactating sows with the dopamine agonist Cabergoline: effects on LH and prolactin secretion and responses to challenges with naloxone and morphine |
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| Institution: | 1. Istituto di Clinica Ostetrica Veterinaria, Facolta'' di Medicina Veterinaria, Via del Taglio 8, Parma 43100, Italy;2. Istituto di Clinica Medica Veterinaria, Facolta'' di Medicina Veterinaria, Via del Taglio 8, Parma 43100, Italy;3. Department of Agricultural, Food and Nutritional Science, Faculty of Agriculture, Forestry, and Home Economics, 310C Agriculture/Forestry Building, University of Alberta, Edmonton, Alberta T6G 2P5, Canada;1. Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada;2. Department of Animal Medicine, Division of Infectious Diseases, Faculty of Veterinary Medicine, Zagazig University, Zagazig City, Sharkia Province, Egypt;3. School of Public Health, College of Health Sciences, University of Nairobi, Nairobi, Kenya;4. IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA), Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Cerdanyola del Vallès, Barcelona, Spain;5. Universitat Autònoma de Barcelona, 08193, Bellaterra, Cerdanyola del Vallès, Barcelona, Spain;1. Harbour Veterinary Hospital 251, London, Road North End PO2 9HA, Portsmouth, UK;2. Department and Clinic of Animal Reproduction, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Głeboka 30, 20-612, Lublin, Poland;3. Department of Human Physiology, Medical University in Lublin, Radziwiłłowska 11, 20-080, Lublin, Poland;4. University Center of Veterinary Medicine, Agricultural University of Cracow, Al. Mickiewicza 24/28, 30-059, Cracow, Poland;5. Department of General and Transplant Surgery and Nutritional Treatment, Medical University of Lublin, Jaczewskiego 8, 20-954, Lublin, Poland;6. Department of Virology and Immunology, Institute of Microbiology and Biotechnology, Maria Curie-Sklodowska University, Akademicka 19, 20-033, Lublin, Poland;7. Department of Epizootiology and Clinic of Infectious Diseases, University of Life Sciences in Lublin, Głęboka 30, 20-612, Lublin, Poland;1. IACTEC Medical Technology Group, Instituto de Astrofísica de Canarias, 38205 San Cristóbal de La Laguna, Spain;2. Department of Electrical Engineering, Group of Signal Theory and Communications, Universidad de Oviedo, 33204 Gijón, Spain;3. Applied Magnetism and Optics Group, Universidad de Cádiz, 11519 Cádiz, Spain;4. Department of Signals and Communications, University Research Institute for Biomedical and Health Research, Universidad de Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Spain;1. Department of Animal Medicine Production and Health-University of Padova, via dell’Università 16, 35020 Legnaro, PD, Italy;2. Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Istanbul, Turkey;1. Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA;2. Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, United States;3. Department of Animal Science, University of California, Davis, CA, 95616, USA;4. Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC, 27709, USA |
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| Abstract: | This study was conducted to examine the effects of chronic administration of a long-acting dopamine agonist, Cabergoline, on LH and prolactin secretion during lactation in the sow. The effect of the administration of the opioid antagonist naloxone and the agonist morphine in Cabergoline treated animals was also evaluated. In Part I of the experiment, 16 sows were treated as either CONT sows (n=4; control, no treatment); CAB sows (n=4; treated with Cabergoline from days 10 to 26 of lactation); CAB+NAL sows (n=4; received Cabergoline treatment and naloxone challenges); CAB+MORP sows (n=4; treated with Cabergoline and morphine challenges). Plasma LH and prolactin concentrations were measured in blood samples taken from all sows during 6-h periods at days 12, 19 and 26 of lactation. To extend the results at the most critical response period at day 26, another 11 sows were allocated in Part II to either Control (n=3), Cabergoline (n=4) or Cabergoline and morphine (n=4) treatments as for Part I, but the effect of treatments were only confirmed in a single period of sampling at day 26 of lactation. Cabergoline treatment alone increased (P<0.001) mean plasma LH concentrations at day 26 but not at days 12 and 16 of lactation. In contrast, naloxone challenges given in the presence of Cabergoline treatment increased (P<0.05) mean LH at days 12 and 19 of lactation but not at day 26. Morphine challenges in the presence of Cabergoline treatment decreased (P<0.05) mean LH concentrations only at day 26 of lactation, but did not completely reverse the effect of Cabergoline. No treatment differences in plasma oestradiol-17β were detected at any time. Plasma prolactin decreased (P<0.001) in response to treatment with Cabergoline but there were no additional effects of naloxone or morphine. These data provide evidence for the existence of dopaminergic and opioidergic regulation of LH secretion in lactation in the sow and the relative influence of these systems changes as lactation progresses. Furthermore, the data suggest that the stimulatory effect of Cabergoline treatment on LH secretion in late lactation may be mediated by its effects on an inhibitory opioidergic mechanism. Finally, the data provide conclusive proof that prolactin does not directly influence LH secretion or estrogenic activity of the ovary during lactation in the sow. |
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