Procyanidin B2 from lotus seedpod regulate NO/ADMA/DDAH pathway to treat insomnia in rats

Recent studies show that nitric oxide/asymmetric dimethylarginine/dimethylarginine dimethylaminohydrolase (NO/ADMA/DDAH) pathway may contribute to the development of sleep disorder. The objective of this study was to explore the inhibitory effect of procyanidin B2 from lotus seedpod (LSPC), a naturally occurring catechin compound, on insomnia and the mechanisms involved. The experiments were performed in brain from Sprague-Dawley rat control and insomniac rats treated or not with LSPC (15, 30, and 45 mg/kg, intragastrically) for 7 days. LSPC treatment reduced walking time and forelimb lifting-up frequency, cerebral levels of noradrenaline, glutamic acid, ADMA, sleep latency, and 8-isoprostane; increased sleep duration, cerebral concentrations of 5-hydroxytryptamine, γ-aminobutyric acid, and NO concomitantly with upregulated cerebral expression of DDAH 1, DDAH2, and neuronal NO synthases in insomniac rats. The present results suggest that LSPC may regulate NO/ADMA/DDAH pathway by inhibiting oxidative stress to treat insomnia in rats when sleep evaluation was achieved on the basis of behavioral criteria.