Effect of Acupuncture on Hypothalamic–Pituitary–Adrenal System in Maternal Separation Rats

Abstract

The maternal separation (MS) animal model has been widely used to study early life stress and several psychiatric conditions such as depression and anxiety. In this study, we investigated the effect of acupuncture on anxiety-related behaviors and hypothalamic-pituitary-adrenal (HPA) system in MS-induced early life stress of Sprague-Dawley rat pups (14-21 postnatal days). For determining anxiety-related behaviors, the elevated plus-maze test was performed. The effects of acupuncture on the activation of stress were measured by assessing plasma levels of corticosterone (CORT) and adrenocorticotropin hormone (ACTH). The hypothalamic immunoreactivity (IR) of arginine vasopressin (AVP) was also examined. Acupuncture was conducted at acupoint HT7, which is used to treat mental disorders in Oriental medicine, for seven consecutive days. Acupuncture significantly decreased the frequencies of open arm entries and the amount of time spent in the open arms in MS rats. In addition, acupuncture reduced CORT and ACTH levels in plasma of MS rats, and AVP-IR in the hypothalamic paraventricular nucleus of MS rats. In conclusion, acupuncture reduced anxiety-related behaviors and modulated the HPA system. These findings suggest that acupuncture at HT7 may be useful as a therapeutic treatment in MS-induced early life stress.