We investigated the efficacy of Ocimum basilicum (OB) essential oils for treating depression related behavioral, biochemical and histopathological changes caused by exposure to chronic unpredictable mild stress (CUMS) in mice and to explore the mechanism underlying the pathology. Male albino mice were divided into four groups: controls; CUMS; CUMS plus fluoxetine, the antidepressant administered for pharmacological validation of OB; and CUMS plus OB. Behavioral tests included the forced swim test (FST), elevated plus-maze (EPM) and the open field test (OFT); these tests were performed at the end of the experiment. We assessed serum corticosterone level, protein, gene and immunoexpression of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) as well as immunoexpression of glial fibrillary acidic protein (GFAP), Ki67, caspase-3 in the hippocampus. CUMS caused depression in the mice as evidenced by prolonged immobility in the FST, prolonged time spent in the open arms during the EPM test and reduction of open field activity in the OFT. OB ameliorated the CUMS induced depressive status. OB significantly reduced the corticosterone level and up-regulated protein and gene expressions of BDNF and GR. OB reduced CUMS induced hippocampal neuron atrophy and apoptosis, and increased the number of the astrocytes and new nerve cells. OB significantly increased GFAP-positive cells as well as BDNF and GR immunoexpression in the hippocampus.

Depression is a significant public health concern all over the world, especially in modern communities. This study aims to assess the efficacy of musk in alleviating the behavioral, biochemical and histopathological changes induced by chronic unpredictable mild stress (CUMS) in an animal model of depression and to explore the underlying mechanism of this effect. Male Swiss albino mice were divided into four groups (n = 10): control, CUMS, CUMS+fluoxetine and CUMS+musk. At the end of the experiment, behavioral tests were administered and serum corticosterone and testosterone levels were assessed. Surface markers, proteins and gene expressions of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) in the hippocampus were assessed. The immunoexpression of glial fibrillary acidic protein, Ki67 and caspase-3 was also assessed. Data were analyzed using the Statistical Package for the Social Sciences and a P value of less than 0.05 was considered significant. Musk alleviated the behavioral changes caused by CUMS and reduced elevated corticosterone levels. It reduced CUMS-induced neuronal atrophy in the CA3 and dentate gyrus of the hippocampus and restored astrocytes. Musk reduced the neuro- and glial apoptosis observed in stressed mice in a manner comparable to that of fluoxetine. Musk induced these effects through up-regulating both BDNF and GR gene and protein expressions. Musk has an antidepressant-like effect in an animal model of depression, so it is advisable to assess its efficacy in people continually exposed to stressors.