Paper Information

Title: 

EFFECT OF OXYTOCIN ON HYPOTHALAMUS-PITUITARY-ADRENAL (HPA) AXIS IN RESPONSE TO IMMOBILIZATION STRESS IN SHEEP

Type: POSTER
Author(s): HOUSHMAND F.,RAFIEIAN M.,RAHMANI H.R.
 
 
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2007Volume 18
 
 
Abstract: 

Introduction: Oxytocin (OT) is released in response to a variety of stressful stimuli. The effect of OT on stress dependent on the species, the stressor & experimental condition used. The aim of this study was to examine the effects of OT on the plasma levels of cortisol (CS) in sheep under control conditions, during & after immobilization stress (is).
Method: At first blood samples were collected (n=10), then 5 animals were injected with OT (100, 150, 300 ng) and the others with saline. Experiment 2 (n=5) used a similar schedule except that sheep subjected to stress. Blood were collected every 60min after4h on a stress box and 2h later when stress end. Plasma [CS] was determined by RIA.
Result: Control animals showed a large increase in plasma [CS] in the 90min period of injection. This response was significantly & dose dependently decreases by of administered OT at 100, 150ng in the 90 & 210min. When the sheep were exposed to immobilization additionally infused with OT, there was less enhancement of the secretion of CS. Whereas CS levels decreased in the 30min period following injection of the 3 doses of OT, the stimulatory effect of stress on CS release was decreased significantly by OT at highest dose. These results indicate that exogenous OT mutilates CS release in no stressed and in sheep subjected to restrained stress.
Discussion: Results confirm the inhibitory influence of low-dose of OT infusion on CS levels & support the hypothesis that, besides its hypophysial inhibitory action on ACTH release, OT acts also at the adrenal gland level to decrease CS release. The depressive action of OT upon CS secretion in stressed sheep is matched by corresponding observations on man and it seems that endogenous OT may inhibit or attenuate some hormonal responses to stress.

 
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