PURPOSE: To investigate the effects of acute tamoxifen treatment on hepatic cytochrome P450 (CYP) expression and circulating thyroid and growth hormone (GH) levels in intact adult male rats. METHODS: Rats were injected subcutaneously with peanut oil (vehicle) or tamoxifen at a dosage of 20 or 200 mg/kg for 2 consecutive days. Blood for GH measurements was collected on day 34. Rats were sacrificed at 37 days after treatment, trunk blood was collected, and hepatic microsomes were prepared. RESULTS: Mean body weight of rats treated with tamoxifen at 200 mg/kg was decreased compared to vehicle-treated rats throughout the 5-week period after treatment. Hepatic CYP2A1-dependent testosterone 7alpha-hydroxylase activity and CYP2A1 protein content were increased, whereas CYP2C11-mediated testosterone 2alpha- and 16alpha-hydroxylase activities and CYP2C11 protein content were decreased significantly following tamoxifen administration. Peak plasma GH levels were 60% lower and nadir plasma GH levels were 30% higher in tamoxifen-treated relative to vehicle-treated rats. In contrast, serum triiodothyronine and thyroxine levels were not affected by tamoxifen treatment. CONCLUSIONS: Hepatic CYP enzyme expression was altered and body weight was decreased in adult male rats 5 weeks after treatment with tamoxifen. This alteration corresponded to changes in plasma GH levels.
PURPOSE: To investigate the effects of acute tamoxifen treatment on hepatic cytochrome P450 (CYP) expression and circulating thyroid and growth hormone (GH) levels in intact adult male rats. METHODS:Rats were injected subcutaneously with peanut oil (vehicle) or tamoxifen at a dosage of 20 or 200 mg/kg for 2 consecutive days. Blood for GH measurements was collected on day 34. Rats were sacrificed at 37 days after treatment, trunk blood was collected, and hepatic microsomes were prepared. RESULTS: Mean body weight of rats treated with tamoxifen at 200 mg/kg was decreased compared to vehicle-treated rats throughout the 5-week period after treatment. Hepatic CYP2A1-dependent testosterone 7alpha-hydroxylase activity and CYP2A1 protein content were increased, whereas CYP2C11-mediated testosterone 2alpha- and 16alpha-hydroxylase activities and CYP2C11 protein content were decreased significantly following tamoxifen administration. Peak plasma GH levels were 60% lower and nadir plasma GH levels were 30% higher in tamoxifen-treated relative to vehicle-treated rats. In contrast, serum triiodothyronine and thyroxine levels were not affected by tamoxifen treatment. CONCLUSIONS: Hepatic CYP enzyme expression was altered and body weight was decreased in adult male rats 5 weeks after treatment with tamoxifen. This alteration corresponded to changes in plasma GH levels.
Authors: I Kostoglou-Athanassiou; K Ntalles; J Gogas; C Markopoulos; V Alevizou-Terzaki; P Athanassiou; E Georgiou; C Proukakis Journal: Horm Res Date: 1997
Authors: J Cuzick; D Allen; M Baum; J Barrett; G Clark; V Kakkar; E Melissari; C Moniz; J Moore; V Parsons Journal: Eur J Cancer Date: 1992 Impact factor: 9.162
Authors: Noel N Kim; Miljan Stankovic; Abdullah Armagan; Tulay T Cushman; Irwin Goldstein; Abdulmaged M Traish Journal: BMC Womens Health Date: 2006-09-13 Impact factor: 2.809