Stress upregulates 2-arachidonoylglycerol levels in the hypothalamus, midbrain, and hindbrain, and it is sustained by green nut oil supplementation in SAMP8 mice revealed by DESI-MSI

Abstract

The endocannabinoid 2-arachidonoylglycerol (2AG) is an important modulator of stress responses. Its level in the brain increases in response to stress, but region-specific effects of stress on brain 2AG are not well known yet. Moreover, green nut oil (GNO), oil extracted from the seeds of Plukenetia volubilis has several health benefits, but its effects on brain 2AG levels are unknown. Therefore, we conducted this study to explore the effects of stress and GNO supplementation on 2AG levels in specific brain regions of senescence-accelerated mouse prone 8 (SAMP8). In this study, desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) revealed that water-immersion stress for three days significantly increased 2AG levels in several brain regions of SAMP8 mice, including the hypothalamus, midbrain, and hindbrain. No significant change was observed in the relative abundance of brain 2AG in stress given SAMP8 mice after eighteen days of removing stress load compared to control SAMP8 mice. GNO supplementation also increased brain 2AG in SAMP8 mice without stress load. Additionally, GNO supplementation sustained the increased brain 2AG levels in stress given SAMP8 mice after eighteen days of removing stress load. Among all brain regions, a relatively higher accumulation of 2AG was noted in the hypothalamus, midbrain, and hindbrain of GNO-fed SAMP8. Our data explored the potentiality of GNO supplementation to improve brain 2AG levels which might be used to treat anxiety and depressive behaviors.

Keywords: 2-arachidonoylglycerol; DESI-MSI; Green nut oil; Plukenetia volubilis; SAMP8 mice; Stress.