engleski

Alteration of ObR expression in the Sprague-Dawley rat brain as a consequence of acute and chronic stress

Introduction. Acute and chronic stressors challenge homeostasis which is maintained by sympathomedullary pathway and hypothalamus- pituitary-adrenal axis. Obesity is a disorder of homeostatic mechanisms which control energy balance through leptin and leptin receptor (ObR). Males are losing weight upon chronic stress while females gain weight. However, the complete mechanism of body weight maintenance during chronic stress and gender differences are still unclear. The aim of this study was to evaluate whether the acute and chronic stress affect ObR expression in the brain of male, female (NON-OVX) and ovariectomized (OVX) Sprague-Dawley rats. Methods. Study included 72 four-months-old Sprague-Dawley rats divided in males, NONOVX and OVX group. These groups were further subdivided in acute, chronic and control group. Acute stress was provoked by cold restraint while chronic stress by combination of different stressors within the 10-day stress session. Stress sessions were repeated 3 times with 2 week pause in-between. Sham groups were exposed to the same environment as stress groups, but with stressor excluded. When the rats were 28 weeks old brains were collected and free-floating immunohistochemical staining was performed using ObR antibody. Results. ObR positive neurons were analyzed in the barrel field (S1BF) and periventricular (Pe), arcuate (Arc) and lateral hypothalamic nuclei (LH). While there was no alteration of ObR expression in the Pe, the differences in Arc, LH and S1BH are observed. Acute stress lowers expression of ObR in all animals and these regions with exception of LH in OVX where ObR expression is increased. Contrary, chronic stress brings expression of ObR to control levels or even higher. Discussion and conclusion. Exposure to acute stress causes down-regulation of ObR receptor in barrel field and critical regions of hypothalamus. Homeostatic mechanisms are able to stabilize levels of ObR during chronic stress, at least in young animals.

leptin receptor; stress; brain; rat

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