The role of ghrelin-octanoyl-acyl-transferase in thermoregulation.

Abstract

Ghrelin is a gastrointestinal peptide that promotes a positive energy balance. The enzyme ghrelin O-acyltransferase (GOAT) esterifies an n-octanoic acid to the peptide, thereby enabling ghrelin to bind and activate the ghrelin receptor. Although ghrelin has previously been implicated in the control and maintenance of body core temperature (BCT), the role that this acylation may play in thermoregulation has not been examined. We aimed to investigate the endogenous role of ghrelin acylation in thermoregulation. In this study, we exposed mice lacking the enzyme GOAT as well as wild-type (WT) control mice to cold temperatures under ad libitum and fasting conditions. Additionally, we investigated the role of GOAT in metabolic adaptation to cold temperatures by analyzing BCT and energy metabolism in mice with and without GOAT that were progressively exposed to low ambient temperatures (31-7 C). We find that regardless of nutritional status, mice lacking GOAT maintain a similar BCT as their WT counterparts during an 8 h cold exposure. Furthermore, mice lacking GOAT maintain a similar BCT and metabolic adaptation asWT controls during acclimatization to low ambient temperatures. We conclude that the absence of the enzyme GOAT does not play a significant role in maintenance of BCT or metabolic adaptation during exposure to low external temperatures.