Programação metabólica do testículo pelo tratamento com injeção de leptina em ratos nos primeiros dias de vida

Abstract

Leptin has an important role in regulating the reproductive system besides its main role in the regulation of body weight and food intake. The aim of this study was to evaluate the effect of leptin administration during the neonatal period in the testis function of the adult offspring. Twenty-four pups from 12 dams were separated into 2 groups: Leptin group: injected with 50μL of leptin (80ng/gBW, subcutaneous); control group: injected with the same volume of saline solution for the first 10 days of life. All animals were killed at 90 days of life. Parameters analyzed: Body weight, linear growth and food consumption; onset of puberty, lipid profile, testosterone and estradiol serum levels, gene (Real time PCR) and protein expression (Western blot) of OBRa, OBRb, aromatase, AR, ER, testicular morphometry, spermatozoa number, morphology and viability. Data were expressed as mean ± standard error. Statistical significance was determined by student s t-test. Leptin injection led to a reduction in food consumption (p≤0.008) from day 26 to 40 and from day 70 onward while body weight (p≤0.03) and linear growth (p≤0.05) were reduced from 26 to 45 days of life. Pituitary (p≤0.0006), hypothalamus (p≤0.01), prostate(p≤0.003), testis (p≤0.008), epididymis(p≤0.004) and bladder (p≤0.009) weights were significantly reduced by leptin injection. Leptin injection also advanced the onset of puberty (C=45.0 ± 0.3; L=41.6 ± 0.3; days, P≤0.0001). In relation to lipid profile, leptin administration led to an increase in TG (C=116.5 ± 15.9; L=172.6 ± 19.7; ng/dL, P≤0.05) and a reduction in HDL (C=33 ± 1.5; L=24 ± 3.5; ng/dL, P≤0.02) serum levels. Testosterone serum levels (C=5.2 ± 1.0; L=1.1 ± 0.28; ng/mL, P≤0.003) were also reduced by leptin. All gene evaluated by real time PCR showed an increase in its expression: OBRa (C=0.32 ± 0.04; L=0.69 ± 0.16; P≤0.04), OBRb (C=0.37 ± 0.06; L=0.70 ± 0.16; P≤0.03), AR (C=0.28 ± 0.02; L=0.71 ± 0.16; P≤0.02), Aromatase (C=0.31 ± 0.04; L=0.53 ± 0.09; P≤0.04), ER-α (C=0.79 ± 0.03; L=0.92 ± 0.03; P≤0.01), ER-β (C=0.29 ± 0.03; L=0.7286 ± 0.16; P≤0.02). On the other hand, the protein expression of OBR (C=4.4 ± 0.29; L=6.6 ± 0.84; P≤0.05), ER-α (C=0.4 ± 0.02; L=0.44 ± 0.02; P≤0.03) and aromatase (C=0.4 ± 0.03; L=0.5 ± 0.01;AU, P≤0.04) were increased while AR (C=0.16 ± 0.01; L=0.09 ± 0.01; P≤0.009) was reduced by leptin administration. The morphometric analysis showed that leptin led to an increase in the total area (C=64.6 ± 3.1; L=56.1 ± 2.1; μm² P≤0.01) and luminal areas (C=40.6 ± 2.3; L=48.7 ± 0.9; μm² P≤0.004) and in the epithelial height (C=21.5 ± 1.2; L=24.6 ± 1.1; μm P≤0.03), while the length of seminiferous tubule was reduced (C=2200 ± 350; L= 1100 ± 110; cm P≤0.006). Leptin administration led to an increase in the total number of spermatozoa (C=20x107 ± 2x107; L=30x107 ± 5x107; P≤0.009) and in the number of abnormalities (C=40.6 ± 1.9; L=45.8 ± 1.2; P≤0.049). We can conclude that leptin has an important role in the morphology and testis function. The leptin effect seems to be direct in this tissue since the gene and protein expression of OBR, AR, ER and aromatase and spermatozoa number were changed by leptin administration.