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ROLE OF GABAA AND NMDA RECEPTORS OF RAPHE IN THE CONTROL OF TERMOEFFECTORS OF PRECOCIOUS BIRDS
Author(s) -
Silva Caroline Cristina,
Gargaglioni Luciane Helena,
Bícego Kenia Cardoso
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.06601
Subject(s) - bicuculline , thermogenesis , raphe , gabaa receptor , medicine , endocrinology , chemistry , antagonist , ventilation (architecture) , raphe nuclei , nmda receptor , anesthesia , serotonin , serotonergic , receptor , adipose tissue , physics , thermodynamics
It is demonstrated in mammals, at least in rats, that caudal brain regions, such as raphe nuclei, are involved in the modulation of thermoeffectors for heat loss and heat production, such as peripheral vasodilation/vasoconstriction, nonshivering and shivering thermogenesis. If the same scenario occurs in the other group of endothermic vertebrates, i.e., birds, it is still completely unknown. The aim of the present study was to verify the effect of GABA A and GLU inhibition in the Raphe on body temperature (Tb), oxygen consumption and ventilation of precocious birds under neutral (31°C) and cold (25°C), using 7‐day‐old chicks as animal models. For this, the Tb, oxygen consumption (index of thermogenesis) and ventilation were measured in chicks implanted with a mini temperature sensor in the coelomatic cavity, before and each 20 min up to 2hs after intra‐raphe microinjections of the GABA A receptor antagonist, bicuculline (0.05 mM and 0.5 mM), and the NMDA receptor antagonist, AP5 (0.5mM and 5mM), or vehicle. Protocols were approved by the local Animal Care Committee (CEUA of FCAV/Unesp, n° 013907/17). No treatment or condition affected ventilation. Bicuculline (0.5 mM) at 31°C significantly decreased (P <0.05) Tb (vehicle: 41.2±0.1°C; Bicuculline 0.05mM: 40.9±0.1°C; Bicuculline 0.5mM: 40.6±0.2°C) and oxygen consumption (13.9±0.7% decrease) of the animals when compared to the vehicle group. Bicuculline (0.05 mM) at 25°C significantly reduced (P< 0.05) Tb (vehicle: 41.4±0.1°C; Bicuculline 0.05mM: 40.6±0.1°C) and oxygen consumption (12.6±1.4% of decrease) of the animals when compared to the vehicle group. AP6 (5 mM) at 31°C significantly decreased (P< 0.05) Tb (vehicle: 41.3±0.1°C; AP5 0.5mM: 40.9±0.1°C; AP5 5mM: 40.3±0.2°C) and oxygen consumption (14.7±0.6% decrease) of the animals when compared to the vehicle group. AP5 (0.5 mM) at 25°C significantly reduced (P <0.05) Tb (vehicle: 41.2±0.2°C; AP5 0.5mM: 40.7±0.1°C) and oxygen consumption (17.4±3.1% of decrease) of the animals when compared to the vehicle group. Our preliminary results suggest that GABA A and NMDA receptors inhibition in Raphe neurons show an inhibitory effect on Tb of chicks affecting thermogenesis under neutral (31°C) and cold (25°C) conditions. Other thermoeffectors possibly involved in this response is currently under investigation. Support or Funding Information FAPESP (2017/17278‐2)