Cannabidiol/cannabidiolic acid-rich hemp (Cannabis sativa L.) extract attenuates cognitive impairments and glial activations in rats exposed to chronic stress

Abstract

Ethnopharmacological relevance: Hemp (Cannabis sativa L.) is increasingly being recognized for its medicinal properties beside utilizing it for food, oil, and textile fibers. The high level of cannabidiol (CBD) content in hemp's flowers shows promising neuroprotective properties without causing psychotomimetic or addictive effects. Recently, products containing CBD and its precursor, cannabidiolic acid (CBDA), have been used to treat stress-related cognitive impairment. However, the therapeutic potential of hemp extract remains inadequately explored.

Aim of the study: To investigate the effect of CBD/CBDA-rich hemp extract on learning and memory, neuroendocrine alterations, and hippocampal neuropathological changes in the chronic restraint stress model.

Materials and methods: Chronic restraint stress (CRS) was induced in male Wistar rats by immobilizing them in a restrainer for 6 h per day for 21 consecutive days. CBD/CBDA-rich hemp extract (10 and 30 mg/kg, intraperitoneal injection) was administered daily, 1 h before restraint. After the last day of CRS, behavioral tests for cognition were conducted using the Y-maze and object recognition tests. Serum corticosterone (CORT) levels were measured by ELISA. Histopathological changes, neuronal density, and the activation of microglia and astrocytes were visualized using cresyl violet and immunohistochemical staining.

Results: A high dose of CBD/CBDA-rich hemp extract effectively ameliorated CRS-induced cognitive impairment and reversed HPA axis hyperactivity in CRS rats by reducing CORT levels and adrenal gland weight. Additionally, CBD/CBDA-rich hemp extract protected CRS-induced damage to hippocampal neurons. Further analysis showed that CBD/CBDA-rich hemp extract reduced specific markers of microglial activation (ionized calcium-binding adaptor molecule-1, Iba-1) and astrocytic structural protein (glial fibrillary acidic protein, GFAP) in CRS rats.

Conclusion: CBD/CBDA-rich hemp extracts remarkably reversed the stress-induced behavioral perturbations and hippocampal damage, suggesting its ameliorative effect on stress response.

Keywords: Cannabidiol (CBD); Cannabidiolic acid (CBDA); Cannabis sativa L.; Chronic restraint stress (CRS); Hemp.