Acute Food Deprivation Decreases the Expression of Methamphetamine-Induced Locomotor Sensitization in Rats

Abstract

INTRODUCTION: AMPH and METH are known to increase DAergic signaling in the brain reward system by stimulating the release of DA through the reversal of DAT function. However, there is evidence that insulin signaling pathways have the ability to modulate DAT functions. Some studies have reported that hypoinsulinemia attenuates DAT functions, and as a consequence, psychostimulant-induced behaviors are reduced. In the present study, we examined the effects of acute food deprivation, which also reduces insulin levels, on METH-induced locomotor sensitization. METHODS: Separate groups of rats were treated with METH (1 mg/kg i.p.) or saline for 5 days (development phase). On the test day (expression phase), the groups were treated with METH or saline after food deprivation for 24 h. Furthermore, in separate groups of rats, levels of glucose, insulin, and phosphorylation of Akt at Ser473 were also examined after food deprivation for 24 h. RESULTS: The results showed that repeated administration of METH induced a progressive increase in locomotor activity in rats during the development phase. However, METH administration in the expression phase produced a decrease in locomotor activity after 24 h of food deprivation. In addition, the results showed that a reduction in glucose, insulin, and Akt levels occurred as a result of food deprivation. CONCLUSION: These results are in line with previous studies and suggest that food deprivation reduces some behavioral effects of psychostimulants such as AMPH and METH.