Exogenous growth hormone administration during total sleep deprivation changed the microRNA-9 and dopamine D2 receptor expressions followed by improvement in the hippocampal synaptic potential, spatial cognition, and inflammation in rats.

Abstract

Disorders caused by total sleep deprivation can be modulated by the administration of growth hormone, which could affect the expression of microRNA-9 and dopamine D2 receptor expressions followed by improvement in the hippocampal synaptic potential, spatial cognition, and inflammation in rats. The present study aimed to elucidate the putative effects of exogenous growth hormone (GH) against total sleep deprivation (TSD)-induced learning and memory dysfunctions and possible involved mechanisms. To induce TSD, rats were housed in homemade special cages equipped with stainless steel wire conductors to induce general and inconsistent TSD. They received a mild repetitive electric shock to their paws every 10 min for 21 days. GH (1 mg/kg, sc) was administered to adult young male rats once daily for 21-day-duration induction of TSD. Spatial learning and memory performance, inflammatory status, microRNA-9 (miR-9) expression, dopamine D2 receptor (DRD2) protein level, and hippocampal histological changes were assayed at scheduled times after TSD. The results indicated that TSD impaired spatial cognition, increased TNF-α, decreased level of miR-9, and increased DRD2 levels. Treatment with exogenous GH improved spatial cognition, decreased TNF-α, increased level of miR-9, and decreased DRD2 levels after TSD. Our findings suggest that GH may play a key role in the modulation of learning and memory disorders as well as the ameliorating abnormal DRD2-related functional disorders associated with miR-9 in TSD.