Changes in peripheral energy metabolism during audiogenic seizures in rats

Abstract

Plasma glucose and lactate, hepatic glycogen and epididymal adipose tissue lipogenesis and lipolysis were studied in Wistar audiogenic rats (WARs), a genetic model of epilepsy, under three experimental conditions, i.e., before, 3 min after and 10 min after seizures induced by intense sound exposure. Plasma glucose increased 3 min after the seizure onset and rose to a peak after 10 min. Hepatic glycogen decreased significantly in susceptible audiogenic rats compared to nonepileptic controls, even before sound stimulation. A marked ( approximately 10-fold) rise was observed in plasma lactate levels 3 and 10 min after the seizures compared to the response of the control group. Lipogenic activity showed a marked decrease even after stimulation with 25 ng/ml insulin. Based on these results, WARs showed reduced isoproterenol-stimulated lipolysis compared to control animals, whereas basal levels only differed significantly at 10 min after seizure activity. In conclusion, it can be inferred from these results that (a) the increase in plasma glucose after stimulation might result from sequential interaction of autonomic activation at seizure onset; (b) excessive muscular activity was at least partially responsible for the steady rise in plasma lactate concentrations; (c) audiogenic seizures, which increase adrenergic activity, induce desensitization of the beta-adrenergic lipolytic pathway in epididymal adipose tissue; (d) genetic selection for audiogenic seizure susceptibility results in pronounced alterations at multiple levels of metabolic regulation.