Melatonin receptors in neonatal pig brain and pituitary gland
Autor: | L T Hannah, J M Bassett, Lynda Williams |
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Rok vydání: | 1999 |
Předmět: |
endocrine system
Pituitary gland medicine.medical_specialty Swine GTPgammaS Receptors Melatonin Receptors Cytoplasmic and Nuclear Receptors Cell Surface Biology Melatonin receptor Binding Competitive Melatonin Iodine Radioisotopes Pineal gland chemistry.chemical_compound Endocrinology Internal medicine medicine Animals Tissue Distribution Brain medicine.anatomical_structure chemistry Animals Newborn Hypothalamus Guanosine 5'-O-(3-Thiotriphosphate) Pituitary Gland Pars tuberalis medicine.drug Endocrine gland |
Zdroj: | Journal of pineal research. 26(1) |
ISSN: | 0742-3098 |
Popis: | Summer infertility remains a major problem in domestic pigs. It has been proposed that sows which display this trait are inherent seasonal breeders. The influence of photoperiod on domestic pigs has been difficult to ascertain as significant diurnal fluctuations in blood levels of the pineal hormone, melatonin, which provide a direct neuroendocrine transduction of the ambient photoperiod in other species, remain questionable in adult pigs. To investigate whether the pig is potentially receptive to melatonin, central sites of action for this hormone were localized and characterized within the brain and pituitary of the neonatal pig by in vitro autoradiography using 2-((125)I)iodomelatonin. Specific binding was distributed over a number of discrete regions of the brain including the cerebral cortex, hypothalamus, thalamus, brainstem, and cerebellum. The choroid plexus, and the pars tuberalis and pars distalis of the pituitary were also specifically labeled. Specific binding was completely abolished in the presence of 10(-7) M melatonin, and inhibited in the presence of 10(-4) M GTPgammaS (guanosine-5-0-(3-thiotriphosphate)), a non-hydrolysable analogue of GTP, in all regions examined, indicating that binding is representative of a G-protein coupled receptor. Characterization studies showed that 2-((125)I)iodomelatonin binding was saturable with a dissociation constant (Kd) in the low picomolar range (approximately 30 pM). Competition studies with iodomelatonin, melatonin, N-acetylserotonin and serotonin (5-HT) gave IC50 values similar to those previously characterized for the melatonin receptor in the ovine pars tuberalis. |
Databáze: | OpenAIRE |
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