Sex-specific Effects of a2d-1 in the Ventromedial Hypothalamus of Female Mice Controlling Glucose and Lipid Balance

Abstract

The thrombospondin receptor alpha2delta-1 (a2d-1) plays essential roles promoting the activity of SF1 neurons in the ventromedial hypothalamus (VMH) and mediating glucose and lipid metabolism in male mice. Its role in the VMH of female mice remains to be defined, especially considering that this hypothalamic region is sexually dimorphic. We found that a2d-1 depletion in SF1 neurons differentially affects glucose and lipid balance control and sympathetic tone in females compared to males. Mutant females show a modest increase in relative body weight gain when fed a high-fat diet (HFD) and normal energy expenditure, indicating that a2d-1 is not a critical regulator of energy balance in females, similar to males. However, diminished a2d-1 function in the VMH leads to enhanced glycemic control in females fed a chow diet, in contrast to the glucose intolerance reported previously in mutant males. Interestingly, the effects of a2d-1 on glucose balance in females are influenced by diet. Accordingly, females but not males lacking a2d-1 exhibit diminished glycemic control as well as susceptibility to hepatic steatosis when fed a HFD. Increased hepatic sympathetic tone and CD36 mRNA expression and reduced adiponectin levels underlie these diet-induced metabolic alterations in mutant females. The results indicate that a2d-1 in VMH SF1 neurons critically regulates metabolic function through sexually dimorphic mechanisms. These findings are clinically relevant since metabolic alterations have been reported as a side effect in human patients prescribed gabapentinoid drugs, known to inhibit a2d-1 function, for the treatment of seizure disorders, neuropathic pain, and anxiety disorders.