A TCM herbal formula increases IGF-1 and IGFBP-1 levels in the sera and ovaries in an aged female rat model of menopause

Abstract

Menoprogen (MPG), a TCM herbal formula improves menopausal symptoms in clinical trials, however its mechanism has remained elusive. Previous studies show that MPG is not directly estrogenic, thus the goal of this study was to investigate the effects of MPG on IGF-1 and IGFBP-1 levels in an aged female rat model of menopause. In a six-armed study, 14-month-old Sprague-Dawley (SD) female rats (n = 8 per arm) were randomly divided into an untreated aged group, an E2-treated aged group (17β-estradiol), and three arms with increasing doses of MPG groups (162, 324, or 648 mg/kg/day). The sixth arm contained four-month-old SD female rats as a normal comparison group. Four weeks after MPG or E2 administration, the animals were sacrificed after blood draws, and then ovarian tissues were excised. The levels of E2 and progesterone (P4) were determined by radioimmunoassay, and serum and ovarian tissue levels of IGF-1, IGFBP-1, and IGF-1 receptor (IGFR) were determined by ELISA. Compared with the normal group, the aged rats had significantly reduced serum levels of E2, P4, and IGF-1 and increased serum and ovarian tissue levels of IGFBP-1. MPG restored serum IGF-1 and IGFBP-1 levels and down-regulated the ovarian levels of IGFBP-1, which were closely related to increases of E2 and P4 levels in the aged rats. No significant differences were observed between the three doses of MPG for either IGF-1 or IGFBP-1. MPG has a direct in vivo effect in aged female rats by positively regulating serum and ovarian IGF-1 and IGFBP-1 levels.