Effects of N-carbamylglutamate and L-arginine on steroidogenesis and gene expression in bovine granulosa cells

Dietary rumen-protected L-arginine or N-carbamylglutamate enhances placental amino acid transport and suppresses angiogenesis and steroid anabolism in underfed pregnant ewes

This study aimed to investigate the effects of dietary supplementation of underfed Hu ewes from d 35 to 110 of gestation with either rumen-protected L-arginine (RP-Arg) or N-carbamylglutamate (NCG) on placental amino acid (AA) transport, angiogenic gene expression, and steroid anabolism. On d 35 of gestation, 32 Hu ewes carrying twin fetuses were randomly divided into four treatment groups, each consisting of eight ewes, and were fed the following diets: A diet providing 100% of NRC's nutrient requirements for pregnant ewes (CON); A diet providing 50% of NRC's nutrient requirements for pregnant ewes (RES); RES diet plus 5 g/d NCG (RES + NCG); or RES diet plus 20 g/d RP-Arg (RES + ARG). On the d 110 of pregnancy, blood samples were taken from the mother, and samples were collected from type A cotyledons (COT; the fetal portions of the placenta). The levels of 17β-estradiol and progesterone in the maternal serum and both the capillary area density (CAD) and capillary surface density (CSD) in type A COT were decreased in response to Arg or NCG supplementation when compared to the RES group. The concentrations of arginine, leucine, putrescine and spermidine in type A COT were higher (P < 0.05) in the RES + ARG or RES + NCG group than in the RES group. The mRNA expression levels of inducible nitric oxide synthase (iNOS) and solute carrier family 15, member 1 (SLC15A1) were increased (P < 0.05) while those of progesterone receptor (PGR) and fibroblast growth factor 2 (FGF2) were decreased in type A COT by supplementation with either NCG or RP-Arg compared to the RES group. The results suggest that providing underfed pregnant ewes from d 35 to 110 of gestation with a diet supplemented with NCG or RP-Arg improves placental AA transport, and reduces the expression of angiogenic growth factor genes and steroid anabolism, leading to better fetal development.

The significance of N-carbamoylglutamate in ruminant production

Improving the efficiency and production of grazing ruminants to support food and fiber production, while reducing the environmental footprint and meeting the welfare needs of the animals, is important for sustainable livestock production systems. Development of new technologies that can improve the efficiency of nitrogen (N) utilization in ruminants, and that are effective and safe, has important implications for ruminant livestock production. N-carbomoylglutamate (NCG) is a functional micronutrient that stimulates endogenous synthesis of arginine, which can improve survival, growth, lactation, reproductive performance, and feed efficiency in mammals. There is a growing body of evidence to support the potential of dietary NCG supplementation to improve the productive capacity and N utilization efficiency of ruminants. This review summarizes the current literature on the effects of dietary supplementation with NCG in ruminants and impacts on production and potential to reduce the environmental footprint of farmed ruminant livestock. The current literature highlights the potential for commercial application in ruminant livestock to improve productivity and N utilization efficiency.

In Vitro Effects of Enniatin A on Steroidogenesis and Proliferation of Bovine Granulosa Cells

The emerging Fusarium mycotoxins enniatins (ENNs) have been the focus of new research because of their well-documented existence in various cereal and grain products. Research findings indicate that reproductive disorders may be caused by exposure to Fusarium mycotoxins, but little work has evaluated ENNs on reproductive function. Therefore, to determine the effects of ENNA on the proliferation and steroidogenesis of granulosa cells (GC), experiments were conducted using bovine GC cultures. In vitro, ENNA (1−5 μM) inhibited (p < 0.05) hormone-induced GC progesterone and estradiol production. The inhibitory effect of ENNA on estradiol production was more pronounced in small- than large-follicle GC. In large-follicle GC, 0.3 μM ENNA had no effect (p > 0.10) whereas 1 and 3 μM ENNA inhibited GC proliferation. In small-follicle GC, ENNA (1−5 μM) dramatically decreased (p < 0.05) GC proliferation. Using cell number data, the IC50 of ENNA was estimated at 2 μM for both follicle sizes. We conclude that ENNA can directly inhibit ovarian function in cattle, decreasing the proliferation and steroid production of GC.

Progesterone Induces Apoptosis and Steroidogenesis in Porcine Placental Trophoblasts

Placentation and placental steroidogenesis are important for pregnancy and maternal−fetal health. As pregnancy progresses, the main site of progesterone (P4) synthesis changes from the corpus luteum to the placenta, in which placental trophoblasts are the main cell type for P4 synthesis. Therefore, this study investigated the effects of P4 on apoptosis and steroidogenesis in porcine placental trophoblasts and the underlying molecular mechanisms. Porcine placental trophoblasts were treated with different concentrations of P4 for 48 h in a serum-free medium in vitro. Cell number, steroidogenesis, and relevant gene and protein expression levels were detected. A high dose of P4 (10.0 μM) significantly increased P4 (p < 0.01), androstenedione (p < 0.05), testosterone (p < 0.05), and estradiol (p < 0.05) production in porcine placental trophoblasts compared with that in control cells, while a low dose of P4 (1 × 10−3 μΜ) had no marked impact on steroid production. The mRNA expression of apoptosis-related genes (CASP3, CASP8, and Bax) (p < 0.05) and steroidogenesis-related genes (CYP11A1, CYP19A1, and StAR) (p < 0.01) was upregulated, and the expression of HSD3B and HSD17B4 was inhibited (p < 0.05) in the porcine placental trophoblasts treated with high doses of P4. Low doses of P4 had a lighter effect on gene expression than high doses. The expression of apoptosis-related proteins CASP3 (p < 0.05), and Bax (p < 0.01) and steroidogenesis-related proteins CYP19A1 (p < 0.05) and StAR (p < 0.01) was raised, but the proliferation-related protein CCND2 (p < 0.01) was downregulated in the pTr cells treated with high dose of P4. In comparison, a low dose of P4 inhibited the expression of Bax, CYP11A1 (all p < 0.01), and CCND2 (p < 0.05), but the expression of CASP3 (p < 0.05) and StAR (p < 0.01) was upregulated. In summary, excessive P4 can induce the apoptosis of porcine placental trophoblasts and lead to abnormal steroidogenesis in the placenta and hormone imbalance.

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

Heat stress (HS) during pregnancy adversely affects uterine vascular perfusion and fetal 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 hemodynamics and uteroplacental thickness under environmental HS conditions. For this purpose, pluriparous (n=12) HS-pregnant buffaloes (mid-gestation, 180-190 d; 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 hemodynamics (ipsi-lateral and contralateral to the pregnant horn) were examined utilizing B-mode and color Doppler ultrasonography, respectively. The serum levels of progesterone (P4), estradiol 17 β (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 < 0.05) CUPT and MUA diameter values starting at 24 h post-treatment and onward than the control buffalo cows. In addition, there were improvements (P<0.05) 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, colored areas toward 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 hemodynamics, NO levels, and steroids production in mid-pregnant buffalo cows under environmental heat stress conditions which could improve fetal growth and development.

Effects of bone morphogenetic protein 4, gremlin, and connective tissue growth factor on estradiol and progesterone production by bovine granulosa cells

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-β family of proteins that have been implicated in the paracrine regulation of granulosa cell (GC) function, but whether responses to BMPs change with follicular size or interact with connective tissue growth factor (CTGF) or BMP antagonists (e.g., gremlin [GREM]) to directly affect GC function of cattle is unknown. Therefore, to determine the effects of BMP4 on proliferation and steroidogenesis of GCs and its interaction with GREM or CTGF, experiments were conducted using bovine GC cultures. In vitro, BMP4 (30 ng/mL) inhibited (P < 0.05) follicle-stimulating hormone (FSH) plus insulin-like growth factor 1 (IGF1)-induced progesterone and estradiol production by large- and small-follicle GCs, but the inhibitory effect of BMP4 on estradiol production was much more pronounced in large-follicle GCs. In small-follicle GCs, BMP4 had no effect (P > 0.10) on IGF1-induced proliferation, but GREM inhibited (P < 0.05) cell proliferation and estradiol and progesterone production in IGF1 plus FSH-treated GCs. In large-follicle GCs, BMP4 (10 to 30 ng/mL) increased (P < 0.05) GC numbers and GREM (100 ng/mL) blocked this effect. In large-follicle GCs, CTGF inhibited (P < 0.05) FSH plus IGF1-induced progesterone and estradiol production, and CTGF blocked the stimulatory effect of BMP4 on GC proliferation. These results indicate that BMP4, GREM, and CTGF inhibit GC aromatase activity and progesterone production. Also, the stimulatory effect of BMP4 on GC proliferation and the inhibitory effects of BMP4 on GC steroidogenesis are more pronounced in large vs. small follicles.

Influence of N-acetylcysteine on steroidogenesis and gene expression in porcine placental trophoblast cells

N-acetylcysteine (NAC) is a widely used anti-inflammatory agent and antioxidant in vivo and in vitro. As a nutritional supplement, NAC can improve production and reproductive performances in animals through enhancing placental function and regulating hormone production. Trophoblast proliferation and steroid hormone production are two major functions in the placenta. We hypothesized that the effects of NAC on placental function is due to its direct and indirect effects on gene expression in placental trophoblast cells (pTr). To evaluate this hypothesis, we investigated the effects of NAC on steroidogenesis, gene expression, and cell proliferation in porcine pTr in vitro. pTr were treated with NAC in serum-free medium for 24 h with different concentrations (0, 0.1 μM, 1.0 μM, 10.0 μM, 0.1 mM, 1.0 mM, and 10.0 mM). Low-dose NAC (1 μM) stimulated pTr proliferation and decreased progesterone production, while increasing estradiol production (P < 0.05). High-dose NAC (10 mM) suppressed cell proliferation (P < 0.05), but had no effect on steroidogenesis. Low-dose NAC increased CCDN1 and decreased CASP3 and CASP8 mRNA levels (P < 0.05), whereas high-dose NAC decreased CDK4 and CCDN1 and increased CASP3 mRNA levels (P < 0.05). NAC had no effect on the mRNA abundance of StAR and HSD3B. Low-dose NAC upregulated CYP19A1 mRNA expression, and high-dose NAC downregulated CYP11A1 mRNA abundance (P < 0.05). Only low-dose NAC increased NOS3 mRNA abundance and tetrahydrobiopterin reduction (BH4/BH2 ratio). We conclude that NAC may act directly and indirectly on pTr with a dose-dependent manner and may regulate placental function by affecting pTr differentiation via regulating pTr steroid synthesis, cell proliferation, and apoptosis in sows.

Effects of N-carbamylglutamate on steroidogenesis and relative abundances of mRNA transcripts in pig placental trophoblasts

Supplementation of N-carbamylglutamate (NCG) improves gestation outcomes, with increased piglet within-litter uniformity of birth weight and reduced peripheral steroid concentrations in pregnant sows and ewes. It was hypothesized that the effect of NCG on placental function results from direct effects on the placental trophoblasts. There, therefore, was investigation of the effects of NCG on pig placental trophoblast (pTr) steroidogenesis, mRNA transcript abundance, and cell proliferation in vitro. The pTr were treated with NCG in serum-free medium for 24-48 h. Treatment with NCG inhibited pTr progesterone, androstenedione, testosterone (all P <  0.01), and estradiol (P <  0.05) production, whereas it promoted (P <  0.05) pTr proliferation. Treatment with NCG suppressed (P <  0.05) the relative abundances of CYP11A1, CYP19A1, and CASP3 and increased abundances of CCDN1 (P <  0.01) and CDK4 (P <  0.05) mRNA transcripts in pTr, whereas NCG treatment had no effect (P >  0.10) on relative abundances of StAR, HSD17B4, or HSD3B mRNA transcripts. Treatments with NCG can increase pTr cell numbers of sows through upregulating CCND1 and CDK4 and suppressing CASP3 mRNA transcript abundances, while modulating steroidogenesis through effects on CYP11A1 and CYP19A1 mRNA transcript abundances. It is concluded that NCG may have a direct action on pTr and may regulate placental function by suppressing pTr differentiation as a consequence of lesser steroid synthesis while promoting pTr proliferation and inhibiting apoptosis in sows.

Effect of dietary N-carbamylglutamate on development of ovarian follicles via enhanced angiogenesis in the chicken

N-carbamylglutamate (NCG), an analogue of N-acetyl-L-glutamate (NAG), can increase arginine synthesis in mammals and improve the reproductive performance. However, the effect of NCG on poultry laying performance is still unclear. This study investigated the effect of dietary NCG on development of chicken ovarian follicles. The dosage and timing for NCG administration were evaluated for its effect on follicular development. Results showed that supplementation with 1% NCG in the diet for 14 D led to accelerated development of growing follicles (over 60 μm in oocyte diameter) and significantly increased feed intake and feed efficiency. Plasma amino acids (AA) analysis showed that feeding with 1% NCG significantly increased of plasma AA levels. RNA-seq analysis revealed that NCG supplementation upregulated expression of genes related to angiogenesis and cell proliferation, but downregulated expression of apoptosis-related genes. Meanwhile, RT-qPCR and Western blot analysis validated the RNA-seq results. Moreover, NCG enhanced plasma NO level; upregulated expression of PKG-I, Raf1, and p-p38; and increased angiogenesis of the ovaries. In conclusion, dietary NCG (1% for 14 D) can promote development of ovarian follicles by increasing angiogenesis in ovaries of the chicken.

Determination of N-Carbamylglutamate in Feeds and Animal Products by High Performance Liquid Chromatography Tandem Mass Spectrometry

N-carbamylglutamate (NCG), a synthetic analogue of N-acetylglutamate, is an activator of blood ammonia conversion and endogenous arginine synthesis. Here, we established an accurate quantitative determination of NCG in feeds, animal tissues, and body fluids using the high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The sample pretreatment procedures included extraction with 0.5% of formic acid in water/methanol (80/20, v/v), and purification using an anionic solid phase extraction cartridge. Satisfactory separation of NCG was achieved in 20 min with the application of an Atlantis T3 column, and a confirmative detection of NCG was ensured by multiple reaction monitoring of positive ions. NCG spiked in feeds, tissues, and body fluids were evaluated in regard to linearity, sensitivity, recovery, and repeatability. Recoveries for different sample matrices were in the range of 88.12% to 110.21% with relative standard deviations (RSDs) less than 8.8%. Limits of quantification were within the range of 0.012 to 0.073 mg kg⁻¹ and 0.047 to 0.077 μg mL⁻¹ for solid and liquid samples, respectively. This study will provide a solid foundation for the evaluation of availability and metabolic mechanism of NCG in animals.

Effects of N-carbamylglutamate and arginine on steroidogenesis and proliferation of pig granulosa cells in vitro

Results of in vivo studies indicate dietary N-carbamylglutamate (NCG) and arginine (ARG) can enhance reproductive performance in gilts. It was hypothesized that both NCG and ARG will alter hormone-induced estradiol (E2) production by granulosa cells (GC), explaining why these compounds could improve reproductive performance in pigs. The objective of these studies, therefore, was to evaluate the direct effects of NCG and ARG on porcine GC proliferation and steroidogenesis, using an in vitro cell culture system. The GC from small (SM; 1-5 mm) and large (LG; >5 mm) pig follicles were cultured for 2 days in 5% fetal bovine serum and 5% porcine serum-containing medium followed by 2 days in serum-free medium containing 500 ng/mL of testosterone (as an E2 precursor), and NCG or ARG at various doses in the presence of either follicle-stimulating hormone (FSH; 30 ng/mL), insulin-like growth factor-1 (IGF1; 30 ng/mL), or both. Numbers of GC were determined at the end of the experiment and concentrations of progesterone (P4) and E2 in culture medium were determined. Results indicated that LG-follicle GC were more responsive to NCG and ARG than SM-follicle GC. Specifically, in LG-follicle GC, NCG inhibited (P <  0.05) basal and FSH-induced P4 and E2 production but stimulated cell numbers; whereas ARG inhibited FSH-induced E2 production and cell numbers. In SM-follicle GC, treatment with NCG and ARG decreased IGF1 plus FSH induced P4 production, but E2 production and cell proliferation were not affected. These studies indicate that NCG and ARG may directly affect follicular function in pigs.

Effects of l-arginine on endometrial estrogen receptor α/β and progesterone receptor expression in nutrient-restricted sheep

This study aimed to determine the effects of l-arginine (L-Arg) supplementation on steroid hormone receptors in non-pregnant ovine endometrium. All experimental ewes were randomly assigned to either a control group (n = 6), a nutrient-restricted group (n = 6), or an L-Arg supplemented nutrient-restricted group (n = 6). The effects of L-Arg on estrogen receptor α/β (ERα/β) and progesterone receptor (PGR) expression in the ovine endometrium were assessed. Our results showed that levels of ERβ and PGR expression were significantly increased by nutrient restriction, but L-Arg counteracted the effect of nutrient restriction on ERβ and PGR expression (p < 0.05). Also, expression of endometrial ERα was substantially increased (p < 0.05) by L-Arg supplementation. Furthermore, ERα/β and PGR were mainly detected in the endometrial luminal epithelium and glandular epithelium. Therefore, we isolated and identified endometrial epithelial cells (EECs) from sheep. Different concentrations of L-Arg were added to investigate the effects on ERα/β and PGR in EECs. The expression levels of endothelial nitric oxide synthase, ERβ, and PGR were significantly increased in response to low-concentration (200 μmol) L-Arg supplementation, which subsequently decreased with a high concentration (800 μmol) (p < 0.05). Otherwise, ERα expression was remarkably increased at both L-Arg concentrations in EECs (p < 0.05). Overall, the results indicated that L-Arg performed crucial roles in the regulation of ovine steroid hormone receptor expression in the endometrium. The results of this study provide a theoretical basis and technical means for the normal function of endometrium in response to low nutrient levels.