Effects of adrenergic agents on stress-induced brain microstructural and immunochemical changes in adult male Wistar rats

This preliminary study aims to explore how adrenergic agents modulate stress response and affect stress-induced behavioral and brain changes in rodents. A total of 40 adult male Wistar rats were subjected to chronic unpredictable mild stress (CUMS) and randomly divided into five groups. At 30 min before daily stress exposure, the rats were intraperitoneally injected with phentolamine (5 mg/kg), noradrenalin (1.0 mg/kg), propranolol (10 mg/kg), isoproterenol (0.05 mg/kg) or saline, respectively. Another 8 rats served as normal control and received daily saline injection without stress exposure. Open-field behaviors were tested at 1 day after the end of the 21 days of stress exposure. Blood samples were collected for serum corticosterone measurement. Brain sections containing hippocampus were stained with hematoxylin and eosin (H&E) as well as by immunohistochemistry for heat shock protein 70 (hsp70) and nitric oxide synthase type 2 (nos2) analyses. The experimental results demonstrated that repetitive dosing of noradrenalin, phentolamine, and propranolol during chronic stress might region-dependently attenuate stress-induced microstructural and biochemical changes in the hippocampus, although propranolol intensified stress-induced behavioral changes.