Research articleThe nitric oxide serum level and combined utero-placental thickness in buffalo (Bubalus bubalis) affected by pregnancy pathology

The present study aimed mainly to study the level of nitric oxide (NO) and combined thickness of the uterus and placenta (CTUP) in buffaloes affected by pregnancy pathology. Females (n = 104) were classified into three main groups: nonpregnant (n = 10), healthy pregnant (n = 54), and pathologically pregnant (n = 40). The healthy pregnant animals were subgrouped according to the stage of pregnancy to early stage (n = 15), mid stage (n = 15), late stage (n = 19), and full term (n = 5). The animals in which pregnancy was associated with placental pathology were subgrouped to uterine torsion (n = 27), hydroallantois (n = 5), and abortion (n = 8). Blood samples were collected from all animals to estimate the NO level using Griess reaction test. Combined thickness of the uterus and placenta was measured at the most caudal part of the pregnant horn using a rectal ultrasound probe. Placental tissue samples were collected from all pregnant animals just after delivery or abortion for histopathologic section. The results revealed that the level of NO was higher (P ≤ 0.05) in pregnant than in nonpregnant animals (6.89 ± 0.18 μM). Additionally, NO level was decreased significantly at full term (18.26 ± 0.27 μM) when compared to the other stages of pregnancy. Moreover, there was a decrease (P ≤ 0.05) in the level of NO in cases of uterine torsion (22.22 ± 0.46 μM) and hydroallantois (24.20 ± 0.07 μM) in comparison with the normal pregnant buffalo. The CTUP was significantly increased as pregnancy progressed. The CTUP in cases of uterine torsion (18.2 ± 3.3 mm) was higher (P < 0.05) than in healthy pregnant buffalo at the same stage of pregnancy. Additionally, CTUP significantly differed between different types of uterine torsion. There was no significant difference between CTUP in hydroallantois and abortion cases besides healthy pregnancy. Histopathologic examination revealed a great proliferation and hyperplasia of cytotrophoblastic cells only in uterine torsion and hydroallantois cases. In conclusion, NO level and CTUP can be used as indicators for pregnancy pathology that is usually associated with presence of cytotrophoblastic cells and placental insufficiency.