Habenula Regulates Cardiovascular Activities in the Insula Cortex in a Rat Model of Epilepsy

Background: Epilepsy has a high mortality rate due to sudden death, which is poorly understood. However, recent research has indicated that it may be associated with fatal arrhythmia, which occurs commonly in insular epilepsy. Objective: To examine the effects of the habenular nucleus on cardiovascular activities in a rat model of insular epilepsy. Methods: Adult rats (n = 32) were divided into four groups: Group A (normal control); Group B (insular epilepsy); Group C (habenular nuclei injury alone); and Group D (bilateral habenular nuclei injury one week prior to the insular epilepsy). A rat model of epilepsy was made in the right insula by microinjection of kainic acid (KA, 0.3 μL). Behavioral activities were observed according to Racine scales. The habenular nuclei were injured by direct current electric shock. Heart rate, blood pressure, and plasma norepinephrine were measured in the four groups under quite conditions or during seizure. Results: We found that the rats in Group B have significantly higher heart rate, blood pressure, and plasma norepinephrine than those in Group A or Group D during seizure; however, there was no difference in blood pressure, heart rate, or plasma norepinephrine between Groups A and C. Moreover, the rats in the Group D had a significant lower blood pressure when compared with those in the Group C; however, no difference was observed in the heart rate and norepinephrine during seizure. Conclusion: The insula cortex has close association with cardiovascular activities in rats from our insula epilepsy model. The habenular nuclei can regulate cardiovascular activities during insular epilepsy.