Neurons in the rat ventral lateral preoptic area are essential for the warm-evoked inhibition of brown adipose tissue and shivering thermogenesis.

AIM: To determine the role of neurons in the ventral part of the lateral preoptic area (vLPO) in CNS thermoregulation.

METHODS: In vivo electrophysiological and neuropharmacological were used to evaluate the contribution of neurons in the vLPO to the regulation of brown adipose tissue (BAT) thermogenesis and muscle shivering in urethane/chloralose-anesthetized rats.

RESULTS: Nanoinjections of NMDA targeting the medial preoptic area (MPA), and the vLPO suppressed the cold-evoked BAT sympathetic activity (SNA), and reduced BAT temperature (TBAT ), expired CO2 , mean arterial pressure (MAP), and heart rate. Inhibition of vLPO neurons with muscimol or AP5/CNQX elicited increases in BAT SNA, TBAT , tachycardia, and small elevations in MAP. The BAT thermogenesis evoked by AP5/CNQX in vLPO was inhibited by activation of MPA neurons. The inhibition of BAT SNA by vLPO neurons does not require a GABAergic input to dorsomedial hypothalamus (DMH), but MPA provides a GABAergic input to DMH. Activation of vLPO neurons inhibits the BAT thermogenesis evoked by NMDA in the rostral raphe pallidus (rRPa), but not that after bicuculline in rRPa. The BAT thermogenesis elicited by vLPO inhibition is dependent on glutamatergic inputs to DMH and rRPa, but these excitatory inputs do not arise from MnPO neurons. Activation of neurons in the vLPO also inhibits cold- and prostaglandin-evoked muscle shivering, and vLPO inhibition is sufficient to evoke shivering.

CONCLUSION: The vLPO contains neurons that are required for the warm ambient-evoked inhibition of muscle shivering and of BAT thermogenesis, mediated through a direct or indirect GABAergic input to rRPa from vLPO. This article is protected by copyright. All rights reserved.