Effects of octreotide in chronically mild stressed rats: possible role of immune and oxidative stress pathways

Impairment of neuroendocrine, immune and antioxidant defenses contribute to pathophysiology of stress-induced depression. Somatostatin executes diverse regulatory effects on endocrine, exocrine and neural functions; however, the possibility that octreotide, a synthetic somatostatin analogue might mitigate stress-induced depression remains elusive. Hence, the current study aimed to explore the immunomodulatory and antioxidant effects of octreotide in a model of chronic mild stress (CMS). This paradigm was performed by exposing rats to a combination of mild unpredictable stressors for 21 days. Fifty male Wistar rats were divided into five groups; (1) control receiving saline, (2) octreotide given to normal unstressed animals. The remaining three groups were subjected to (3) CMS alone or in combination with octreotide (4) 50 μg/kg or (5) 90 μg/kg. Octreotide increased sucrose preference index and attenuated CMS-induced increases in plasma adrenocorticotrophic hormone and corticosterone levels. In addition, octreotide decreased plasma tumor necrosis factor-alpha concentration. Moreover, it prevented CMS-induced oxidative damage by enhancing the antioxidant defenses superoxide dismutase, glutathione reductase and glutathione in the hippocampus. Furthermore, octreotide normalized the elevated malondialdehyde and lactate dehydrogenase levels in the hippocampus. These results demonstrate a possible antidepressant-like activity of octreotide in CMS due to its antioxidant/antiinflammatory aptitude.