Establishment Of The Connection Between Insular Cortex And Hypothalamus And Its Role In Eating Behavior

Eating behavior is complicatedly controlled by metabolic signals,as well as reward,emotional,memorial,attentive and cognitive functions.Hypothalamus is feeding center for its role in regulating eating behavior to keep energy homeostasis.Other brain regions involved in rewarding such as VTA and Nucleus accumbens,or in emotion and memory,such as amygdale and hippocampus,have been found to participate in the regulation of feeding.Insular cortex is the primary taste cortex or gustatory cortex,which receive and integrate taste information.IC is also important to produce memory for internal information,and is called hippocampus of the gut.More importantly,insula has unique function-disgust,which is intrinsic to the insula and is perceived and regulated by the insula.It has been hypothesized that alterations in the activity of insular cortex result in the dysfunction of disgust,which may trigger anorexia nervosa.Previous study has traced the projection from insula to the hypothalamus.However,it is still unknown whether insular cortex is involved in eating behavior.If so,what is the neural circuit for this function of insula.In this study,we focused on the anterior part of insular cortex(AIC).We firstly showed that CaMK?(+)neurons were significantly activated in AIC after intraperitoneal injection of lithium chloride:Next,optically or chemically activation of CaMK?(+)neurons decreased number of the mice to touch the food pellets.While had no effect onthe anxiety behavior.Furthermore,the projection from CaMKII neurons in AIC to the lateral hypothalamic area was established by AAV virus tracing and FG retracing.Specifically activation of the terminals projected from AIC also decreased the number of the mice to touch the food pellets and the total food consumption.Therefore,our data reveal that AIC are involved in regulation of eating behavior and this function is mainly based on the projections of AIC to LHA.