Functional role for preoptic CB1 receptors in breathing and thermal control

Author(s)

Ripamonte, Gabriel C. ^{[1, 2]} ; Gargaglioni, Luciane H. ^[1]

Affiliation

^[1] Sao Paulo State Univ, Dept Anim Morphol & Physiol, UNESP FCAV, Jaboticabal, SP - Brazil

^[2] Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Morfol & Fisiol Anim, Via Acesso Paulo Donato Castellane S-N, BR-14870000 Jaboticabal, SP - Brazil

• Document type: Journal article
• Source: Neuroscience Letters; v. 732, JUL 27 2020.
• Web of Science Citations: 0

Abstract

The anteroventral preoptic region (AVPO) of the hypothalamus is involved in both temperature and breathing regulation. This area densely express cannabinoid receptors type 1 (CB1) that modulate both excitatory and inhibitory synaptic transmission. However, it is still unknown if the endocannabinoid system located in the AVPO participates in breathing control and thermoregulation. Therefore, we tested the participation of CB1 in the AVPO in the modulation of ventilation and thermal control during normoxia and hypoxia. To this end, body temperature (Tb) of Wistar rats was monitored by datallogers and ventilation (V-E) by whole body plethysmography before and after intra-AVPO microinjection of AM-251 (CB1 antagonist, 50 and 100 pmol) followed by 60 min of hypoxia exposure (7% O-2). Intra-AVPO microinjection of the higher dose of AM-251 increased V-E but did not change Tb under resting conditions. Exposure of rats to 7% of inspired oxygen evoked typical hypoxia-induced anapyrexia and hyperventilation after vehicle microinjection. The higher dose of the cannabinoid antagonist increased the hypoxia-induced hyperventilation, in the same magnitude as observed under normoxic condition, whereas the drop in Tb elicited by hypoxia was attenuated. Therefore, the present results demonstrate that the endocannabinoid system acting on CB1 receptors in the AVPO exerts a tonic inhibitory modulation on breathing but seem not be involved in thermoregulation during resting conditions. In addition, activation of CB1 receptors in the AVPO stimulate thermal response during hypoxia, reducing energetically expensive responses, such as the hypoxic hyperventilation. (AU)

• FAPESP's process: 15/04849-6 - Role of TRPV4 channels in thermoregulation in endotherms
• Grantee: Kênia Cardoso Bícego
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/09469-8 - Effect of incubation temperature on chick metabolism, thermoregulation and chemosensitivity
• Grantee: Luciane Helena Gargaglioni Batalhão
• Support Opportunities: Regular Research Grants