Neuroprotective Effect of Marrubium vulgare Extract in Scopolamine-Induced Cognitive Impairment in Rats: Behavioral and Biochemical Approaches.

Simple Summary: Cognitive deficits, including spatial working and recognition memory impairment, are a common feature of Alzheimer's disease with current therapies offering limited efficacy. Marrubium vulgare, a member of the Lamiaceae family, has shown potential to alleviate spatial memory impairment in a model of experimental dementia in rats through its antioxidant and acetylcholinesterase inhibitory activities. The aim of this study was to examine the effect of M. vulgare on recognition memory in healthy and dementia-affected rats after 21 days of oral administration. Memory performance was evaluated by the novel object recognition test. Levels of neurotransmitters acetylcholine, noradrenaline (NA), and serotonin, as well as the protein expression of the brain-derived neurotrophic factor (BDNF) and the phosphorylation of the cAMP response element-binding protein (p-CREB), were measured. The expression levels of BDNF and CREB were evaluated via RT-PCR in the cortex and hippocampus. Our result revealed that M. vulgare ameliorated recognition memory impairment in dementia rats by preserving cholinergic function in the hippocampus, increasing NA levels in the brain, and restoring pCREB expression in the cortex following their reduction in the experimental model used. In healthy rats, the extract upregulated the expression of BDNF and pCREB in the cortex. These findings suggest that M. vulgare has potential as a therapeutic agent for cognitive impairments in various neurodegenerative diseases. The potential of Marrubium vulgare to alleviate scopolamine (Sco)-induced deficits in spatial working memory has drawn considerable scientific interest. This effect is partly attributed to its potent antioxidant and acetylcholinesterase inhibitory (AChEI) activities. This study examined the effects of M. vulgare extract, standardized to marrubiin content, on recognition memory in healthy and Sco-treated rats. Male Wistar rats (200–250 g) were divided into four groups. The extract was orally administered for 21 days and Sco (2 mg/kg) was intraperitoneally injected for 11 consecutive days. Memory performance was assessed using the novel object recognition test. Levels of acetylcholine (ACh), noradrenaline (NA), serotonin (Sero), and brain-derived neurotrophic factor (BDNF) and the phosphorylation of cAMP response element-binding protein (p-CREB) were evaluated in the cortex and hippocampus via ELISA. BDNF and CREB expression levels were assessed using RT-PCR. The results showed that M. vulgare significantly alleviated Sco-induced memory impairment, preserved cholinergic function in the hippocampus, increased NA levels in the brain, and restored pCREB expression in the cortex following Sco-induced reduction. In healthy rats, the extract upregulated BDNF, pCREB, and Bcl2 expression. Our findings indicate that the neuroprotective effects of M. vulgare may be linked to the modulation of cholinergic function, regulation of NA neurotransmission, and influence on key memory-related molecules. [ABSTRACT FROM AUTHOR]