The Antidepressant-like Effects of Estrogen-mediated Ghrelin

Brain Volume Loss, Astrocyte Reduction, and Inflammation in Anorexia Nervosa

Anorexia nervosa is the third most common chronic disease in adolescence and is characterized by low body weight, body image distortion, weight phobia, and severe somatic consequences. Among the latter, marked brain volume reduction has been linked to astrocyte cell count reduction of about 50% in gray and white matter, while neuronal and other glial cell counts remain normal. Exact underlying mechanisms remain elusive; however, first results point to important roles of the catabolic state and the very low gonadal steroid hormones in these patients. They also appear to involve inflammatory states of "hungry astrocytes" and interactions with the gut microbiota. Functional impairments could affect the role of astrocytes in supporting neurons metabolically, neurotransmitter reuptake, and synapse formation, among others. These could be implicated in reduced learning, mood alterations, and sleep disturbances often seen in patients with AN and help explain their rigidity and difficulties in relearning processes in psychotherapy during starvation.

Intracerebroventricular Ghrelin Administration Increases Depressive-Like Behavior in Male Juvenile Rats

Major depressive disorder (MDD) is arguably the largest contributor to the global disease and disability burden, but very few treatment options exist for juvenile MDD patients. Ghrelin is the principal hunger-stimulating peptide, and it has also been shown to reduce depressive-like symptoms in adult rodents. We examined the effects of intracerebroventricular (icv) injection of ghrelin on depressive-like behavior. Moreover, we determined whether ghrelin increased neurogenesis in the hippocampus. Ghrelin (0.2-nM, 0.5-nM, and 1.0-nM) was administered acutely by icv injection to juvenile rats to determine the most effective dose (0.5-nM) by a validated feeding behavior test and using the forced swim test (FST) as an indicator of depressive-like behavior. 0.5-nM ghrelin was then administered icv against an artificial cerebrospinal fluid (aCSF) vehicle control to determine behavioral changes in the tail suspension test (TST) as an indicator of depressive-like behavior. Neurogenesis was investigated using a mitogenic paradigm, as well as a neurogenic paradigm to assess whether ghrelin altered neurogenesis. Newborn hippocampal cells were marked using 5′-bromo-2′-deoxyuridine (BrdU) administered intraperitoneally (ip) at either the end or the beginning of the experiment for the mitogenic and neurogenic paradigms, respectively. We found that ghrelin administration increased immobility time in the TST. Treatment with ghrelin did not change mitogenesis or neurogenesis. These results suggest that ghrelin administration does not have an antidepressant effect in juvenile rats. In contrast to adult rodents, ghrelin increases depressive-like behavior in male juvenile rats. These results highlight the need to better delineate differences in the neuropharmacology of depressive-like behavior between juvenile and adult rodents.

Pharmacological effects of berberine on mood disorders

Berberine, a natural isoquinoline alkaloid, is used in herbal medicine and has recently been shown to have efficacy in the treatment of mood disorders. Furthermore, berberine modulates neurotransmitters and their receptor systems within the central nervous system. However, the detailed mechanisms of its action remain unclear. This review summarizes the pharmacological effects of berberine on mood disorders. Therefore, it may be helpful for potential application in the treatment of mood disorders.

Gender Differences in Plasma Ghrelin Levels in Hemodialysis Patients

Ghrelin is an orexigenic hormone mainly secreted by the stomach, and it decreases according to the severity of gastric atrophy. Ghrelin has multiple favorable functions, including protein anabolism enhancement, anti-inflammatory activity, and cardiovascular protection, and is associated with survival in hemodialysis (HD) patients. Although the plasma level and role of ghrelin may be different depending on gender, they have not been completely assessed in HD patients. We enrolled 80 (male/female: 51/29) maintenance HD patients. An upper gastrointestinal endoscopic examination was performed for all patients to determine the severity of gastric mucosal atrophy and Helicobacter pylori infection. We measured plasma acyl and desacyl ghrelin levels and assessed the association between ghrelin levels and relevant clinical parameters, including nutrition, inflammation, atherosclerosis, and bone metabolism, by gender. Both acyl and desacyl ghrelin levels in female HD patients were significantly higher than those in male HD patients. When stratified by gastric mucosal atrophy, these gender differences were observed only in patients without gastric atrophy. In female patients, acyl ghrelin level was negatively correlated with age. In male patients, both acyl and desacyl ghrelin levels were positively correlated with bone mineral density. Multiple regression analysis showed significant positive correlations between both ghrelin levels and female gender after adjusting for confounding factors. Plasma ghrelin levels were higher in female HD patients than in male HD patients. The gender difference was more evident in patients without gastric atrophy.

Ghrelin produces antidepressant-like effect in the estrogen deficient mice

Recent evidence shows that ghrelin plays an important role in depression. However, it was little known whether ghrelin produces antidepressant-like effect in the ovariectomized mice. The present study was aimed to investigate the antidepressant-like effects of the ghrelin in ovariectomized mice. In the forced swim test, ghrelin significantly decreased immobility time, reversing the “depressive-like” effect observed in ovariectomized mice, and this effect was reversed by the tamoxifen. In addition, immunohistochemical study indicated that ghrelin treatment reversed the reductions in c-Fos expression induced by ovariectomy. An estrogen antagonist tamoxifen also antagonized the effect of ghrelin on the c-Fos expression. Furthermore, the western blotting indicated that brain-derived neurotrophic factor (BDNF) in the hippocampus, but not phosphorylated cAMP response element-binding protein (pCREB)/CREB in the frontal cortex, were affected by ghrelin treatment. Ghrelin treatment significantly increased BrdU expression. Therefore, these findings suggest that ghrelin produces antidepressant-like effects in ovariectomized mice, and estrogen receptor may be involved in the antidepressant-like effects of the ghrelin.