Pregabalin is useful for treating neuropathic pain, but known to increase body weight as a side effect. To investigate the mechanism of this increase in body weight, we focused on dopamine in the lateral hypothalamus (LH) and examined the effects of pregabalin on dopamine levels in the LH and food intake. The dopamine levels in the LH was gradually decreased during fasting. When the animals were fed, dopamine levels in the LH was significantly increased, indicating that dopamine levels in the LH reflects energy state. The systemic injection of pregabalin tended to decrease dopamine levels in the LH after feeding. The dopamine levels in the LH was also significantly increased by glucose injection, which was inhibited by pregabalin. These results suggest that pregabalin inhibits dopaminergic function in the LH, which might increase food intake. To make these points clear, we examined the effects of pregabalin on food intake and blood glucose levels. Pregabalin significantly increased food intake, whereas pregabalin did not affect blood glucose levels. These results indicate that pregabalin stimulates feeding behavior, but not glucose metabolism. Moreover, the non-selective dopamine receptor antagonist cis-(Z)-flupenthixol injected into the LH significantly increased food intake, though neither the dopamine D1 receptor antagonist SCH 23390 nor the D2 receptor antagonist l-sulpiride injected into the LH affected food intake. These results indicate that the inhibition of dopaminergic function in the LH increases food intake. In conclusion, the present results suggest that pregabalin increases food intake through the inhibition of dopaminergic functions in the LH.
Keywords: Dopamine; Feeding behavior; In vivo microdialysis; Lateral hypothalamus; Pregabalin.
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