Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCA210

Poster Communications

Carbon monoxide acts differently on 24-hour and 48-hour dehydration-induced hormone secretion

J. B. Lima1, R. Coletti1, F. M. Vechiato1, F. Lucio-Oliveria2, L. L. Elias1, J. Antunes-Rodrigues1

1. Physiology, University of São Paulo, Ribeirão Preto, São Paulo, Brazil. 2. Southern Minas Gerais Federal Institute, Muzambinho, Brazil.

In the last three decades, evidences of the carbon monoxide (CO) gaseous molecule modulation on neuroendocrine and other homeostatic systems have been reported. Data from literature have indicated CO as a fine modulator of neuroendocrine response to challenges which disrupt hydrosaline balance such as water deprivation (WD) and salt loading. The aim of this present study is to evaluate whether central CO formation blockage or central CO donation in progressive WD leads to different patterns of hormonal secretion. To that, 250g Wistar male rats were submitted to a prior right lateral ventricle cannula implantation under ketamine-xylazine anaesthesia (60 mg e 8 mg/100 g of body weight, i.p., respectively; Coletti et al., 2015 ). After 7 days, the animals were submitted to 24-hour or 48-hour dehydration with free access to chow, in the experiment day they were intracerebroventricularly injected (4 μL) with CO formation inhibitor (ZnDPBG, 50 mM) or vehicle (Na2CO3 50 mM), or CO donor (CORM-3, 100 µM) or vehicle (CORM-3Inactivated, 100 µM) then were euthanized by decapitation after 30 min and trunk blood collected. We observed that, in basal condition (euhydrated animals), the central CO formation inhibition increased only corticosterone (CORT) plasma concentration (F (2, 33) = 6.787, p<0.01; p<0.01 on Newman-Keuls post-hoc) while ZnDPBG injection reversed the 24h WD-induced vasopressin (AVP) (F (1, 84) = 63.05, p<0.0001; p<0.0001 on Newman-Keuls post-hoc) and oxytocin (OT) (F (1, 85) = 78.71, p<0.0001; p<0.0001 on Newman-Keuls post-hoc) secretion increase with no effect on CORT level. Whereas ZnDPBG treatment reversed 48-hour WD-induced AVP, OT and CORT secretion increase (F (2, 33) = 5.036, p<0.05; F (2, 37) = 3.764, p<0.05; F (2, 33) = 19.71, p<0.0001, respectively). Also, we demonstrated that the central CO donation had no effect on AVP, OT and CORT level in basal condition and the same pattern was observed in 24h dehydration-induced OT and AVP plasma concentrations while reduced the 24h dehydration-induced CORT increase (F (1, 41) = 5.430, p<0.05; p<0.01 on Newman-Keuls post-hoc). In 48h dehydration-induced AVP and OT plasma levels increase and the CORM-3 administration potentiates this effect (F (1, 63) = 4.626, p<0.05; p<0.01 on Newman-Keuls post-hoc and F (2, 71) = 5.817; p<0.01; p<0.01 on Newman-Keuls post-hoc, respectively) while there was no effect on CORT concentration. These data together suggest that the same manipulation of central CO content can affect differently the neuroendocrine system depending on the animal hydration state, so that CO effects could act in time-dependent manner in this experimental protocol.

Where applicable, experiments conform with Society ethical requirements