Fig. 5

Blood testosterone levels in male db/db mice were low throughout life from the juvenile period, and their reactions to female mice and hCG were weak. a Changes in blood testosterone levels from 4 to 48 weeks of age in each group are shown (n = 9–11/group). Blood testosterone levels rapidly decreased in NCD-fed male db/+ mice at 36 weeks of age and older. These levels were lower in male db/db mice than in male db/+ mice throughout life, and were also lower in male db/+ mice in the HFD- than in NCD-fed group. b The changes in gonadotropin levels from 4 to 48 weeks of age in each group are shown (n = 9–11/group). The blood LH and FSH levels increased in male db/+ mice after 32 weeks of age. In contrast, these levels were low in male db/db mice throughout life. c A pair of male and female mice were kept in the same cage for 2 weeks (from 10 to 12 weeks of age) in each group (left picture), and the blood testosterone levels were measured in male mice after 2 weeks (right) [n = 8–14 (7–8 males and 0–7 females)/group]. The presence of a female significantly increased blood testosterone levels in male db/+ mice, whereas no significant change was noted in male db/db mice. d Increases in blood testosterone levels after hCG loading (0.5 IU/g body weight) in 12-week-old male db/+ and db/db mice (n = 10/group). hCG increased blood testosterone levels by nearly 10 times in male db/+ mice, but only by approximately 2 times in male db/db mice. Results are expressed as means ± s.e.m. *P < 0.01 between the indicated groups. ^†P < 0.01, ^¶P < 0.01 versus pre-hCG in db/db mice on each diet