Evidence that vasoactive intestinal polypeptide is a physiological prolactin-releasing factor in the bantam hen
| Autor: | S. Harvey, R. J. Sterling, M.C. Macnamee, Peter J. Sharp, R.W. Lea |
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| Rok vydání: | 1986 |
| Předmět: |
endocrine system
medicine.medical_specialty Ovariectomy Vasoactive intestinal peptide Hypothalamus Peptide hormone Biology In Vitro Techniques Nesting Behavior Endocrinology Anterior pituitary Internal medicine medicine Animals Secretion Gonadal Steroid Hormones Histocytochemistry Immunochemistry Prolactin medicine.anatomical_structure Median eminence Ovariectomized rat Animal Science and Zoology Female Chickens hormones hormone substitutes and hormone antagonists Vasoactive Intestinal Peptide |
| Zdroj: | General and comparative endocrinology. 62(3) |
| ISSN: | 0016-6480 |
| Popis: | Vasoactive intestinal polypeptide (VIP)-like material was localised immunohistochemically in the hypothalamus of the bantam hen. Abundant immunoreactive VIP terminals were seen in the external layer of the median eminence and most immunoreactive VIP cell bodies were located in the basal hypothalamus. A few immunoreactive VIP cell bodies and many fibres were found in the preoptic hypothalamus. Intravenous injections of synthetic porcine VIP over a dose range of 12.5 to 100 μg kg−1 body wt resulted in a dose-related increase in concentration of plasma prolactin in incubating bantams deprived of their nests for 24 hr. These doses of VIP did not stimulate the release of growth hormone. Studies in vitro showed that synthetic VIP directly stimulated prolactin release from the anterior pituitary gland. The glands from incubating bantams were more responsive to the prolactin-releasing effects of VIP than were the glands from laying birds. Studies in vitro showed that the amount of prolactin released in response to aniv injection of 50 μg kg−1 VIP was greater in incubating birds deprived of their nests for 24 hr than in laying hens. Prolactin release was not stimulated in ovariectomized hens after an injection of 50 μg kg−1 VIP unless the birds were first treated with oestrogen or oestrogen and progesterone. It was concluded that a VIP-like material in the bantam hypothalamus may be a physiological prolactin-releasing factor acting at least in part at the level of the anterior pituitary gland. The prolactin-releasing ability of VIP is probably related to the amount of prolactin stored in the anterior pituitary gland or to the concentrations of ovarian steroids to which it is exposed. |
| Databáze: | OpenAIRE |
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