Changes of discharge properties of neurons from dorsomedial hypothalamic nuclei during aging in rats

Effects of Intrahypothalamic Administration of microRNA Inhibitors and Mimetics on Blood Plasma Biomarkers in the Rat Aging

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.

Functional properties of aged hypothalamic cells

The hypothalamus, in addition to controlling the main body's vital functions, is also involved in aging regulation. The aging process in the hypothalamus is accompanied by disturbed intracellular pathways, including Ca2+ signaling and neuronal excitability in the brain. Intrinsic electrophysiological properties of individual neurons and synaptic transmission between cells is disrupted in the central nervous system of old animals. However, changes in neuronal excitability and excitation/inhibition balance with aging are specific to the type of neurons, brain region, and species. Glia-neuron interactions play a significant role in the brain and undergo remodeling accompanied by advanced loss of function with aging. In the current review, I have summarized the current understanding of the changes in the brain and especially in the hypothalamus with aging.

Expression of GAD65/67 and VGLUT2 in Mediobasal Nuclei of Rat Hypothalamus during Aging

The expression of glutamate decarboxylase GAD65/67, an enzyme of GABA synthesis, and vesicular glutamate transporter 2 (VGLUT2) in the arcuate, dorsomedial, and ventromedial nuclei of the hypothalamus of young (3 months), adult (12 months), and old male rats (24 months) was studied by Western blotting. In old rats, an increase in the expression of GAD65/67 in the arcuate and dorsomedial, VGLUT2 in the arcuate, dorsomedial, and ventromedial nuclei was observed. Thus, an increase in opposite processes of inhibition and excitation is observed in the hypothalamic nuclei during aging.