Exogenous L‐arginine administration improves uterine vascular perfusion, uteroplacental thickness, steroid concentrations and nitric oxide levels in pregnant buffaloes under subtropical conditions

Abstract

Heat stress (HS) during pregnancy adversely affects uterine vascular perfusion and foetal development. L‐arginine (L‐Arg), a nitric oxide (NO) precursor, has been proven to enhance an organ's vascular perfusion. Therefore, this study aimed to examine the effect of L‐Arg administration on the pregnant buffaloes' uterine haemodynamics and uteroplacental thickness under environmental HS conditions. For this purpose, pluriparous (n = 12) HS‐pregnant buffaloes (mid‐gestation, 180–190 days; temperature humidity index >85) were haphazardly assigned into two groups, either administered a single intravenous (IV) bolus of 5 mg/kg BW of L‐Arg Hcl (n = 6; ARG) or received normal saline (0.9%; IV; 25 ml) that served as a control group (n = 6; CON). Combined uteroplacental thickness (CUPT, mm), middle uterine arteries' (MUA) diameter (mm) and uterine Doppler haemodynamics (ipsilateral and contralateral to the pregnant horn) were examined utilizing B‐mode and colour Doppler ultrasonography, respectively. The serum levels of progesterone (P4), estradiol 17β (E2), nitric oxide (NO) and total antioxidant capacity (TAC) were assayed using commercial kits. The experimental time points were − 1, 0, 2, 4, 24, 48, 72, 96 and 120 h post‐L‐Arg administration. The ARG group showed higher (p < .05) CUPT and MUA diameter values starting at 24 h post‐treatment and onward than the control buffalo cows. In addition, there were improvements (p < .05) in the blood flow parameters in the ipsilateral MUA after L‐Arg treatment evidenced by lower values of pulsatility and resistive indices starting at 48 and 4 h, respectively and onward, and higher values of peak systolic velocity, coloured areas towards the pregnant uterine horn (both 24–72 h). Increases in the NO levels were found during the period between 4 and 120 h in the ARG group compared to the CON group. Moreover, significant increases in the E2 and P4 means were noted in the ARG group, especially at 24 h onward, respectively compared to the CON group. Concerning the TAC status, neither the administration nor the hours affected serum TAC levels in the HS pregnant buffaloes (CON and ARG). In conclusion, L‐Arg administration improved uteroplacental thickness and enhanced uterine haemodynamics, NO levels, and steroids production in mid‐pregnant buffalo cows under environmental heat stress conditions which could improve foetal growth and development.

The effects of aging and gestational month on uteroplacental vascular perfusion, and umbilical artery hemodynamics in pregnant jennies

“…These findings are in accordance with a previous study [ 38 ] that reported an increase in total arterial blood flow rate with advancement of gestational age in the control mares ( P = 0.0001). In this study, we reported a decline in both Doppler indices with pregnancy development; in addition, higher Doppler indices were observed in buffalo at 15 years old [ 19 ]. Finally, there was a negative correlation between uterine Doppler indices in all age jenny, as this means a marked elevation in the uterine vascular supply, especially in the left side.…”

“…Doppler studies of jenny gestational vessels, such as middle uterine and umbilical arteries, could give a prediction value of the gestation outcome [ 18 ]. It was reported that there was a monthly elevation of the uterine artery that led to a strong increase in blood flow rate and a marked decline in the RI during the first 8 months of pregnancy in buffalos [ 19 ].In addition, in mare the same declination in both Doppler indices was observed within gestational months [ 16 ], as this could be due to the presence of endothelial factors that were associated with the marked decline in both Doppler indices and related to arterial hypertension [ 17 ]. However, a study reported that uterine blood flow did not differ between pregnant and nonpregnant mares [ 20 ].…”

Single melatonin injection enhances the testicular artery hemodynamic, reproductive hormones, and semen parameters in German shepherd dogs

“…This data is significant in improving male dog productivity and reproductive pattern [52]. The improvement of testicular blood flow by the melatonin injection led to a mark in both Doppler indices parameters of the distal supra testicular arteries (PI and RI), which have a strong negative correlation with blood velocities parameters (PSV and EDV), testicular volume and intra-testicular colored areas [53][54][55]. The marked linear decline in both two Doppler indices leads to a substantial decrease in the blood flow resistance pattern and, therefore, an elevation of the testicular blood supply with an increase in sufficient nutrients and oxygen within both testes [56][57][58][59][60].…”

Correlation between Uterine Hemodynamics, Sex Steroid Hormone Concentrations, and Enzymatic Antioxidant Levels in Postpartum Buffaloes

“…Reactive oxygen and nitrogen species (ROS and RNS) are produced during oxidative stress. They consist of hydroxyl radicals (OH), superoxide ions, hydrogen peroxide (H 2 O), and nitric oxide radicals (NO), which lead to lipid peroxidation, apoptosis, and infertility [3,4]. The impact of ROS and RNS on fertility is mediated by influencing folliculogenesis, steroidogenesis, and retained placenta [5,6].…”