Antidepressant-like effects of acupuncture via modulation of corticosterone, sex hormones, and hippocampal BDNF expression in male rats.

BACKGROUND: Post-weaning social isolated rodents exhibit pathophysiological changes associated with depression including adrenal axis hyperactivity, gonadal hormone level disturbances, molecular alterations in hippocampus, and immobility behavior in the forced swimming test (FST). Although acupuncture by absorbable thread implantation (acu-catgut, AC) elicits antidepressant-like effects in social isolated rats, AC effects on neuroendocrine and hippocampal molecular alterations have been less characterized. OBJECTIVE: To investigate the participation of gonadal hormones, corticosterone, and brain-derived neurotrophic factor (BDNF) hippocampal expression, on the AC antidepressant-like effects in social isolated male rats. METHODS: Sprague-Dawley male rats were raised in social isolation (SI) or standard conditions, for 11 weeks. AC (on Baihui (Du20), Yintang (E X-HN3), Shenshu (BL 23), Pishu (BL 20), Ganshu (BL 18), Xinshu (BL 15) and Guanyuan (Ren 4)), or Sham-AC (puncturing of acupoints without embedding the thread), was applied during the last three weeks of isolation period. Rats were evaluated in the FST; hormones plasmatic levels and hippocampal BDNF content were quantified by ELISA and Western blotting, respectively. RESULTS: Social isolated rats showed more immobility in the FST and had lower testosterone and estradiol levels, higher corticosterone levels, and reduced hippocampal BDNF content than controls. BDNF level in hippocampus inversely correlated to depression-like behavior. AC but not sham-AC normalized immobility behavior, steroid hormone levels, and BDNF content, as in rats raised in a social environment. CONCLUSIONS: AC antidepressant effect could be related to an improvement of hippocampal BDNF protein expression, as well as corticosterone and sex hormones disturbances associated with prolonged exposure to stress caused by social isolation. Present findings have implications for depression treatment in individuals early exposed to stress.

Antidepressant effects of acupoint stimulation and fluoxetine by increasing dendritic arborization and spine density in CA1 hippocampal neurons of socially isolated rats.

Given the importance of depression and the adverse effects of conventional treatment, it is necessary to seek complementary therapies. In a rat model of depression, this study aimed to assess the behavioral and morphological effects of embedding absorbable thread in acupoints (acu-catgut), and compare the results to those of fluoxetine treatment and the corresponding control groups. Therefore, depressive-like behavior was evaluated with the forced swimming test, and dendritic morphology (in the CA1 hippocampal region) with the Golgi-Cox technique and Sholl analysis. After weaning, male Sprague-Dawley rats were housed in social isolation for 8 weeks to induce depressive-like behavior. They were then given a 21-day treatment by stimulating acupoints with acu-catgut (AC) or fluoxetine (FX) (2 mg/kg). Rats were divided into six groups: Control (socially housed), social isolation (SI), SI + AC, SI + Sham (sham embedding of thread), SI + FX and SI + VH (vehicle). Compared to fluoxetine, acu-catgut treatment was more effective in reversing depressive-like behavior elicited by SI. The SI-induced reduction in dendritic length and spine density in hippocampal CA1 pyramidal neurons was attenuated after prolonged treatment with acu-catgut or fluoxetine. Hence, both treatments proved capable of reversing depressive-like alterations caused by SI, likely due to dendritic remodeling in the hippocampus.