Purpose: To investigate how heat shock protein (HSP) expression, especially inducible HSP 70, is related to the infertility of dioxin-induced testicular toxicity by animal study Materials and Methods: Four week old 30 male Sprague-Dawley rats were divided into 10 groups. Group I, II, III received TCDD(2,3,7,8-tetrachlorodibenzo-p-dioxin) 40μg intraperitoneally and were sacrificed 12hr, 24hr, 48hr later respectively. Group IV, V, VI received vehicle as control group and were sacrificed at the same time. Group VII, VIII received TCDD at 5 weeks of age and were sacrificed 1 week, 4 week later respectively. Group IX, X received vehicle as control group and were sacrificed at the same time. All extracted testes were examined with light microscopy, western blot and immunofluorescence for HSP 70, HSP 90 and inducible HSP 70 and apoptosis stain with TUNEL method. Results: On light microscopy, only group VIII showed significant difference between study and control group. Group VIII and group X showed body weight 139.7gm, 275gm, testis weight 2.17gm, 3.67gm, seminiferous tubule diameter 252μm, 281μm, Johnson score 8.8, 10.0 points, injured tubule ratio 0.131, 0.024 respectively (p<0.01). In western blot and immunofluorescence, inducible HSP 70 was expressed in the group I, II, III, VII, VIII and the intensity increased with time, but in the control group, no expression for inducible HSP 70 was seen. Total HSP 70 was expressed in all study and control groups. On apoptosis stain, intensity peak was noticed at 12hr and decreased after then. HSP 90 was expressed in all study and control groups as well Conclusions: The expression of inducible HSP 70 in the TCDD injured rat testis increased with time and on immunofluorescence stain, the expression site was spermatocytes. Apoptosis appeared initially but decreased after 12hrs. HSP90 and total HSP 70 expression was not changed by TCDD.
