Fig. 1

Induction of low levels of testosterone by leptin receptor KO or HFD. a Comparison of testosterone levels in NCD-fed db/+ and db/db male mice, and HFD-fed db/+ and db/db male mice, at 7 weeks of age (n = 14/group). Testosterone levels were the lowest in HFD-fed db/db mice, and increased in the order, NCD-fed db/db > NCD-fed db/+ mice. b IpGTT analysis in 7-week-old mice on NCD or HFD in each group (n = 12–14/group). The area under the curve (AUC glucose) is shown in the right panel. Glucose homeostasis was exacerbated by HFD feeding. c IpITT analysis in 7-week-old mice in each group (n = 10–13/group) as indicated. d The dose of exogenous testosterone replacement and blood testosterone levels in castrated mice (n = 9–12/group). Exogenous testosterone was administered once every 2 days. Blood testosterone levels increased with an increase in the dose of testosterone replacement. e The dose of exogenous testosterone replacement and blood estradiol levels in castrated mice (n = 9–12/group). Blood estradiol levels did not significantly increase until the dose of exogenous testosterone replacement was elevated to 100 μg/g body weight/2 days. Results are expressed as means ± s.e.m. *P < 0.05, **P < 0.01 between the indicated groups. ^#P < 0.01, ^¶P < 0.01 versus the other group of mice at each time, 2-way ANOVA. ^§P < 0.01 versus the other group of mice on NCD at each time, 2-way ANOVA. ^†P < 0.05 versus another group of db/+ mice. ^‡P < 0.01 versus another group of db/db mice. n.s., no significant