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Oxytocin in the Central Amygdaloid Nucleus Modulates the Neuroendocrine Responses Induced by Hypertonic Volume Expansion in the Rat
Author(s) -
Margatho L. O.,
Elias C. F.,
Elias L. L. K.,
AntunesRodrigues J.
Publication year - 2013
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/jne.12021
Subject(s) - endocrinology , medicine , oxytocin , vasotocin , vasopressin , supraoptic nucleus , hypothalamus , atrial natriuretic peptide , hypertonic saline , chemistry , antidiuretic , tonicity , neuropeptide , receptor
The present study investigated the involvement of the oxytocinergic neurones that project into the central amygdala ( C e A ) in the control of electrolyte excretion and hormone secretion in unanaesthetised rats subjected to acute hypertonic blood volume expansion ( BVE ; 0.3 M N a C l, 2 ml/100 g of body weight over 1 min). Oxytocin and vasopressin m RNA expression in the paraventricular ( P a) and supraoptic nucleus ( SON ) of the hypothalamus were also determined using the r eal t ime‐ polymerase chain reaction and in situ hybridisation. Male W istar rats with unilaterally implanted stainless steel cannulas in the C e A were used. Oxytocin (1 μg/0.2 μl), vasotocin, an oxytocin antagonist (1 μg/0.2 μl) or vehicle was injected into the C e A 20 min before the BVE . In rats treated with vehicle in the C e A , hypertonic BVE increased urinary volume, sodium excretion, plasma oxytocin (OT) , vasopressin ( AVP ) and atrial natriuretic peptide ( ANP ) levels and also increased the expression of OT and AVP m RNA in the P a and SON . In rats pre‐treated with OT in the C e A , previously to the hypertonic BVE , there were further significant increases in plasma AVP , OT and ANP levels, urinary sodium and urine output, as well as in gene expression ( AVP and OT m RNA ) in the P a and SON compared to BVE alone. Vasotocin reduced sodium, urine output and ANP levels, although no changes were observed in plasma AVP and OT levels or in the expression of the AVP and OT genes in both hypothalamic nuclei. The results of the present study suggest that oxytocin in the C e A exerts a facilitatory role in the maintenance of hydroelectrolyte balance in response to changes in extracellular volume and osmolality.