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Different pattern of prolactin release under various acute stress stimuli in rats



Different pattern of prolactin release under various acute stress stimuli in rats



Endocrinologia Experimentalis 22(4): 235-242



In the present study we evaluated the response of lactotrophic function either to mild emotional stress stimuli such as novel environment or to more severe stress of immobilization, insulin-induced hypoglycemia and hypovolemia induced by 12.5% or 25% hemorrhage. Novelty stress lasting 15 min resulted in a significant increase of prolactin (PRL) levels; and 30 min novelty exposure elicited the PRL release of the same magnitude. Immobilization (IMO) caused a higher secretion of PRL with the peak levels in min 15, while in 120 a decline in PRL levels was observed. 25% hemorrhage induced by spontaneous bleeding from the tail artery cannula associated with the blood pressure fall from 108.3 .+-. 1.9 to 69.0 .+-. 4.5 mm Hg led to a pronounced stimulation of PRL secretion which returned to resting levels 30 min after the bleeding. Intravenous administration of 0.5 IU kg-1 insulin diminished the plasma glucose from 6.85 .+-. 0.17 mmol l-1 to 4.24 .+-. 0.19 mmol l-1 20 min after the injection and intraperitoneal administration of 2.5 IU k-1 insulin caused a maximal decrease of blood glucose (from 6.27 .+-. 0.35 mmol l-1 to 2.42 .+-. 0.4 mmol l-1) 40 min after the injection: neither of such insulin-induced hypoglycemia exerted any stimulatory effect on PRL release. These results confirm the sensitivity of lactotrophic axis to mild stress stimuli of novel environment, the rapid and high PRL response to IMO stress and demonstrate that 25% hemorrhage is a clear stimulus for the secretion of PRL. Cerebral glucopenia induced by insulin hypoglycemia in comparison to the effect on other hormones did not act as a stress stimulus to release PRL in rats.

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Accession: 002072460

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PMID: 3243204



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