Age-Dependent Influence of Cholecystokinin on the Impulse Activity of Neurons in the Dorsomedial and Venromedial Nuclei of the Hypothalamus in Rats

Abstract

The aim of the work was to analyze the background and induced by the intravenous administration of the cholecystokinin sulfated octapeptide (CCK), as well as the cholecystokinin antagonist proglumide impulse neuronal electrical activity in the dorsomedial (DMN) and ventromedial (VMN) nuclei of the hypothalamus in young (2–3 months), adults (12 months) and aged (24 months) male rats under urethane anesthesia. The mean frequency of background discharges after the injection of CCK in young rats in the DMN significantly decreased from 1.5 ± 0.4 to 0.2 ± 0.1 impulse/s, in the VMN from 2.0 ± 0.4 to 0.9 ± 0.2 impulse/s. Simultaneous administration of CCK and proglumide did not lead to change of frequencies of neuronal activity in this age group. In adult and aged rats, the mean of the background frequency of discharges of neurons in the DMN and VMN was lower than in young rats and did not change significantly under the influence of CCK and proglumide. In DMN and VMN, the most of the neurons were inhibited by CCK, while in DMN the percentage of neurons inhibited by CCK was higher compared to VMN. The DMN of young animals lacked the CCK-activated neurons that appeared in adult and old animals. Thus, this study confirms the elevation theory of aging, which consists in a decrease in the sensitivity of the hypothalamus to homeostatic signals, in particular, hormones that regulate eating behavior.