Effects of Melatonin in Original Rectal Suppositories on the Neurological Status and Mucosa-Associated and Luminal Microbiota of the Distal Colon in Wistar Rats with Experimental Acute Cerebral Ischemia.

We analyzed the effects of melatonin (MT) administered via rectal suppositories on the composition of the mucosa-associated and luminal microbiota of the distal colon and neurological status of Wistar rats under conditions of experimental acute ischemic stroke (EAIS). The animals received original 100-mg rectal suppositories containing 2.5 mg of MT every 24 h for 3 days. Neurological status was assessed using the Garcia scale and the limb placing test, while microbiota composition in the distal colon was determined using real-time PCR. In rats with EAIS, neurological deficit was observed, characterized by a significant decrease in the Garcia and limb placing scores. In parallel, changes in the colon microbiota were observed: appearance of Clostridioides difficile, Fusobacterium nucleatum, Enterobacter spp., and the disappearance of Enterococcus spp. The administration of original MT-containing rectal suppositories led to partial recovery of neurological deficit, as manifested by in an increase in the Garcia score and limb placing test performance, which was accompanied by the appearance of Bacteroides thetaiotaomicron and the disappearance of Cl. difficile in the colon microbiota. Correlation analysis demonstrated that the amelioration of the neurological deficit was accompanied by changes in the gut microbiota. The effect of MT in rectal suppositories on neurological status and the gut microbiota is attributed to its neuroprotective and bacteriostatic properties.