The pertinence between the concentrations of seminal leptin and genital endocrine hormones and the effect of leptin on spermatic function

Abstract

Objective To explore the pertinence between the concentrations of seminal leptin (lep) and genital endocrine hormones, such as testosterone(T), follicle stimulating hormone( FSH), luteotropic hormone(LH) and insulin growth factor-1 (IGF-1), as well as the effect of Lep on sperm concentration,motility and genital function indexes.Methods 126 cases of infertility and 30 cases of normal fertility were randomly chosen.The contents of Lep, T, FSH and LH were detected by radioimmunoassay (RIA) and the IGF-1 content were detected by immunoradiometric assay (IRMA).The infertility group was divided into group A (sperm count ≥ 20×109 /L), group B (sperm count ＜ 20×109 /L) and group C of azoospermia.According to the number of white blood cell ( WBC ) in 10 high power fields (HPF), the infertility group was further divided into group WBC (WBC count ≥ 1×109 /L) and group Non-WBC(WBC count ＜ 1×109 /L).According to the sperm vitality and the rate of motility, group A was subdivided into the group of normal spermatic vitality (a + b≥50% ), the group of abnormal vitality( a + b ＜ 50% ) (a refers to the number of sperms with fast forward movement, and b refers to the number of sperms with slow or sluggish forward movement), the group of normal rate of spermatic motility( the rate ≥60% ) and the group of decreased rate of motility( the rate ＜60% ).According to the examination results of the normal contrast group, group A and group B were respectively divided into the following groups: the group of normal sperm penetrating power(≥40 mm), the group of decreased penetrating power( ＜ 40 mm), the group of normal intact acrosome rate(≥80% ), the group of decreased intact acrosome rate( ＜ 80% ), the group of normal terminal swelling rate( ≥60% ) and the group of decreased terminal swelling rate( ＜60% ).Results The concentration of Lep in the infertility group was (2.77±0.80) μg/L, significantly higher than the level of Lep [ (1.14 ± 0.31 ) μg/L ] in the contrast group ( t = 10.943,P ＜ 0.05 ).The contents of IGF-1 and T were ( 17.67±8.09) μg/L and (4.84±2.15) nmol/L respectively, significantly lower than the levels of IGF-1 [(24.79±9.32) μg/L] and T [(6.30±2.53) nmol/L] in the contrast group (t =4.205,3.228,P＜0.01).There existed no significant differences of the concentrations of FSH and LH between the two groups ( t = 1.655,1.378 ,P ＞ 0.05 ).The concentrations of FSH and LH were (32.61±9.14) U/L and (40.57 ± 12.40) U/L respectively in the infertility group and(29.63±7.56) U/L and (37.25±9.19) U/L respectively in the contrast group.The concentrations of Lep and IGF-1 and T showed negative correlation in the infertility group (r = -0.237, -0.316,P ＜ 0.01 ).The concentration of Lep had no correlation to the FSH and LH concentration (r = 0.104, 0.112, P ＞ 0.05 ).The concentration of Lep showed a gradual increase within group A, group B and group C (F = 115.93, P ＜ 0.01 ).The leptin contents in the above mentioned normal subgroups were found to be lower than the abnormal groups.Conclusions There exists pertinence between the Lep concentration and the concentrations of TGF-1, T, FSH and LH.Lep may decrease the sperm density and inhibit sperm vitality and the motility rate through inhibiting androgen secretion and sperm capacitation. Key words: Infertility, male; Sperm motility; Semen; Leptin; Testosterone; Follicle stimulating hormone