Inhibition of the dorsomedial hypothalamus substantially decreases brown adipose tissue sympathetic discharge induced by activation of the lateral habenula.

In this study we aimed to test this possibility. In anaesthetized Sprague-Dawley rats, we recorded electrical discharges directly from sympathetic fibres that innervate BAT, as well as BAT temperature. Injections of bicuculline (1 nmol in 100 nl), a neuronal activator by disinhibition, into the LHb increased BAT sympathetic nerve discharge by 4.9 ± 1.4dBμV (n = 7, P < 0.05) and BAT temperature by 1.0 ± 0.1 °C (n = 7, P < 0.01). Subsequent injections of muscimol (0.25 nmol in 100 nl), a neuronal inhibitor, into the DMH promptly reduced BAT sympathetic nerve discharge by 4.7 ± 1.3 dBμV (n = 7, P < 0.05) and BAT temperature by 0.3 ± 0.1 °C (n = 7, P < 0.05). Injections of a mixture of the ionotropic glutamate receptor antagonists, DL-2-Amino-5-phosphonopentanoic acid (AP5) and 6-cyano-7-nitroquinoxaline-2,3-dioneis (CNQX) into the DMH, after activation of the LHb, also significantly decreased BAT sympathetic nerve discharge and BAT temperature. These results suggest that, for sympathetically-mediated BAT thermogenesis, the DMH is part of the neural circuitry linking the LHb with the medullary raphé. PMID: 33220531 [PubMed - as supplied by publisher]
Source: Autonomic Neuroscience - Category: Neuroscience Authors: Tags: Auton Neurosci Source Type: research