The effect of let-7a-5p, miR-9a-3p, miR-132-3p, miR-218a-5p microRNA inhibitors and mimetics, when administered into the dorsomedial nucleus of the hypothalamus (DMN), on the markers of age-related changes in blood plasma in 3-month-old and 24-month-old male rats was studied. In the 24-month-old control rats, the content of C-reactive protein (CRP) increased, and the level of myoglobin decreased compared to the 3-month-old animals. After te administration of miRNA inhibitors, the level of CRP significantly increased, and the content of myoglobin decreased, and after the administration of miRNA mimetics, opposite changes were observed. We found no significant differences in the content of somatotropic hormone and testosterone between the control and experimental groups, as well as between the 3-month-old and 24-month-old animals.