Effects of Moxibustion on Amygdala -HPA Axis in Rats with Kidney-Yang Deficiency Syndrome Induced by Hydrocortisone Injection

Background: The syndrome of kidney-yang deficiency is one of the main syndromes in traditional Chinese medicine. Modern evidences prove that the hypothalamus - pituitary - adrenal axis (HPA axis) function disorder is the main material basis of kidney-yang deficiency syndrome. The upper regulating center, such as hippocampus and amygdala can affected HPA axis. Although moxibustion have a therapeutic effect for kidney-yang deficiency syndromes, the underlying mechanism remains unclear. This study investigated the effect of suspended moxibustion on amygdala and HPA axis and elucidated the possible molecular mechanism of moxibustion in improving kidney-yang deficiency syndrome.Methods: 60 male Sprague-Dawley rats were randomly divided into the normal group ( n=12) and the model-building group (n=48). Rats in the model-building group were given intramuscular injection of hydrocortisone to establish the model of kidney-yang deficiency. The 48 rats successfully modeled were then randomly divided into model group (model, n=12) , carbenoxolone intraperitoneal injection group (CBX, n=12), moxibustion group (moxi, n=12) and moxibustion plus carbenoxolone intraperitoneal injection group (moxi+CBX, n=12). In the moxibustion group, Shenshu (BL23) and Guanyuan (CV4) points were treated with moxibustion for 14 days. After treatment, the level of corticostesone (CORT), adrenocorticotropic hormone (ACTH) and corticotropin-releasing hormone (CRH) in serum, the expressions of mineralocorticoid receptor (MR), glucocorticoid receptor (GR), 11 beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1), corticotropin releasing factor (CRF) and ACTH in rats’ amygdala and (or) hypothalamus, pituitary were detected. Data were analyzed by one-way analysis of variance.Results: Compared with the normal group, the level of CRH, ACTH and CORT in serum, and the mRNA and protein expressions of MR, GR and 11β-HSD1in amygdala, the mRNA and protein expressions of 11β-HSD1 in hypothalamus and CRF mRNA expression in amygdala and hypothalamus, and ACTH mRNA expression in pituitary of rats in the model group were all significantly decreased (P < 0.05 or 0.01). After treatment with moxibustion, except for 11β-HSD1 mRNA expression, the observation index mentioned above were increased to different degrees compared with those in the model group (P < 0.05 or 0.01). Conclusion: Suspended moxibustion can effectively improve the serum levels of ACTH, CRH and CORT, and can up-regulate the mRNA and protein expression of MR, GR , 11β-HSD1, CRF and ACTH in amygdala and hypothalamus of kidney-yang deficiency rats, which may be one of the molecular mechanisms of moxibustion in improving kidney-yang deficiency syndrome.