Existe efeito de programação fetal na prole subsequente de machos da raça Nelore sobre a funcionalidade de membrana mitocondrial, ao realizar desmame antecipado e convencional em fêmeas primíparas e multíparas?

Fetal programming refers to the concept in which factors that affect the health and performance of the pregnant mother can have long-term effects on the offspring, through stimulation or injury during critical periods of gestation, which modulate fetal development and interfere with the performance of the offspring. The aim of this study was to evaluate the effect of early and conventional weaning on cytochrome C oxidation of 3,3'-Diaminobenzidine (DAB), which characterizes the functionality of the mitochondrial membrane, in subsequent male offspring generated by primiparous or multiparous females. Fifty-six Nelore males were evaluated, with an average initial age of 12.5 months. During the fetal development of these animals, their primiparous or multiparous mothers weaned calves at 150 or 240 days (early or conventional weaning, respectively). Thus, of the 56 animals used, 29 came from primiparous females, 14 from the early weaning group and 15 from conventional weaning. The other 27 animals came from multiparous females, 13 from the early weaning group and 14 from conventional weaning. Semen was collected at 12.5, 14.3, 15.5 and 17.3 months of age, using the electroejaculation technique. The functionality of the mitochondrial membrane was assessed by the ultracytochemical test of in situ cytochrome C oxidase activity. For this, an aliquot of 80 μL of semen incubated with 80 μL of DAB (diaminobenzidine - 1 mg/mL in Dulbecco's phosphate buffered saline - DPBS) at 37°C for one hour was used. After incubation, three smears were taken and fixed in 10% formaldehyde for 10 minutes. The slides were air-dried under protection from light and then evaluated under light microscopy at 1000x magnification. Two hundred cells were evaluated per sample and classified into four classes: DAB I: sperm with a fully stained midpiece, with practically all the mitochondria active, indicating high mitochondrial activity. DAB II: sperm with more than half of the mitochondria stained, indicating medium to high mitochondrial activity. DAB III: sperm with less than half of the mitochondria stained, indicating low mitochondrial activity. DAB IV: sperm with the middle part completely unstained, indicating no mitochondrial activity. The results were expressed as a percentage of each subpopulation in the sample. Statistical analyses were carried out using SAS software (Version 9.2; SAS Institute), analyzed by ANOVA using a mixed model (PROC MIXED). When a significant treatment effect was detected, the means were compared using Fisher's method of least significant difference for multiple comparisons. A significant difference was considered when P ≤ 0.05. There was no effect of weaning, mother, or interaction between weaning, mother and age (p > 0.05). However, there was an age effect for mitochondrial membrane potential (p < 0.01), with the data expressed as mean ± standard error of the mean: DAB I: 40.7^c ± 3.6, 62.9^b ± 2.6, 70.4^a ± 2.3 and 70.3^a ± 2.1; DAB II: 39.6^a ± 2.8, 28.3^b ±2.1, 21.6^c ± 1.8 and 26.4^bc ± 1.6; DAB III: 9.7^a ± 0.9, 2.2^b ± 0.7, 1.6^b ± 0.6 and 1.1^b ± 0.5; DAB IV: 13.6^a ± 1.8, 6.6^b ± 1.4, 6.5^b ± 1.2 and 2.3^c ± 1.1 when assessed at 12.5, 14.3, 15.5 and 17.3 months of age, respectively. The results of this study show that early or conventional weaning, using two classes of mothers, has no effect on the functionality of the mitochondrial membrane in the offspring of Nelore males. However, when evaluating the sperm of Nelore breed animals in the prepubertal and pubertal stages, it was possible to observe that as the animals get older, the functionality of the mitochondrial membrane becomes better. It can be concluded that there was no effect of fetal programming when using early and conventional weaning on the subsequent offspring of Nelore males sired by primiparous or multiparous mothers, but the functionality of the mitochondrial membrane becomes better as the Nelore males get older. [ABSTRACT FROM AUTHOR]