Serum concentrations of LH (pg/dL) (a) and FSH (pg/mL) (b) at 53 days old in male rats treated with the herbicide metolachlor during the prepubertal period. Doses: control = 0 mg/kg, MT5 = 5 mg/kg and MT50 = 50 mg/kg. Results are expressed as mean ± SEM, ANOVA, animals/group, *.