Maternal high-salt diet altered PKC/MLC20 pathway and increased ANG II receptor-mediated vasoconstriction in adult male rat offspring

High-Salt Diet Causes Defective Oocyte Maturation and Embryonic Development to Impair Female Fertility in Mice

SCOPE

High salinity has been reported to induce many human disorders in tissues and organs to interfere with their normal physiological functions. However, it is unknown how salinity affects the development of female germ cells. This study suggests that a high-salt diet (HSD) may weaken oocyte quality to impair female fertility in mice and investigates the underlying mechanisms.

METHODS AND RESULTS

C57BL/6 female mice are fed with a regular diet (Control) or a high-salt diet (HSD). Oocyte maturation, fertilization rate, embryonic development, and female fertility are evaluated. In addition, the spindle organization, actin polymerization, and kinetochore-microtubule attachment of oocytes are examined in both groups. Moreover, single-cell transcriptome data are used to demonstrate how HSD alters the transcript levels of genes. The observations confirm that HSD leads to female subfertility due to the deterioration of oocyte and embryo quality. The mechanism underlying reveals HSD compromises the oocytes' autophagy, apoptosis level, and mitochondrial function.

CONCLUSION

The work illustrates that a high concentration of salt diet results in oocyte meiotic arrest, fertilization failure, and early developmental defection that embryos undergo to reduce female fertility in mice by perturbing the level of autophagy and apoptosis, mitochondrial function in oocytes.

Perinatal Fat-Diets Increased Angiotensin II-Mediated Ca2+ through PKC-L-Type Calcium Channel Axis in Resistance Arteries via Agtr1a-Prkcb Gene Methylation

Perinatal malnutrition affects vascular functions, and calcium is important in vascular regulations. It is unknown whether and how perinatal maternal high-fat diets (MHF)-mediated vascular dysfunction occurs via the angiotensin-PKC-L-type-calcium-channels (LTCC) axis. This study determined angiotensin II (AII) roles in the PKC-LTCC axis in controlling calcium influx in the arteries of offspring after perinatal MHF. Mesenteric arteries (MA) and smooth muscle cells (SMCs) from 5-month-old offspring rats were studied using physiological, ion channel, molecular, and epigenetic analysis. Pressor responses to AII were significantly increased in the free-moving MHF offspring rats. In cell experiments, MA-SMC proliferation was enhanced, and associated with thicker vascular wall in the obese offspring. Imaging analysis showed increase of fluorescence Ca²⁺ intensity in the SMCs of the MHF group. Angiotensin II receptor (AT1R)-mediated PKC-LTCC axis in vasoconstrictions was altered by perinatal MHF via reduced DNA methylation at specific CpG sites of Agtr1a and Prkcb gene promoters at the transcription level. Accordingly, mRNA and protein expression of AT1R and PKCβ in the offspring MA were increased, contributing to enhanced Ca²⁺ currents and vascular tone. The results showed that DNA methylation resulted in perinatal MHF-induced vascular disorders via altered AT1-PKC-LTCC pathway in resistance arteries of the offspring, providing new insights into the pathogenesis and early prevention/treatments for hypertension in developmental origins.

Prenatal high-salt diet impaired vasodilatation with reprogrammed renin-angiotensin system in offspring rats

AIMS

High-salt diet is linked to hypertension, and prenatal high-salt diet increases the risk of cardiovascular diseases in the offspring. The present study investigated whether and how prenatal high-salt diet influenced nitric oxide-mediated vasodilatation in the offspring.

METHODS AND RESULTS

Pregnant rats were fed either normal-salt (1% sodium chloride) or high-salt (8% sodium chloride) diet during gestation. Experiments were conducted in 5-month-old male offspring. Sodium nitroprusside (SNP, nitric oxide donor)-induced hypotensive responses (in vivo) and vascular dilatation (in vitro) was significantly attenuated (Emax: 84 ± 2 vs. 51 ± 2, high-salt vs. control, P < 0.001) in the high-salt offspring, indicating reduced vascular relaxations. Pretreatment with Tempol (reactive oxygen species scavenger) alleviated this attenuation. The high-salt offspring showed an increased level of oxidative stress markers in both mesenteric arteries and plasma samples. The antioxidant activity, serum superoxide dismutase and catalase were significantly reduced, whereas malondialdehyde was increased in the high-salt offspring. O2 production, and protein expression of Nox2 and Nox4 in mesenteric arteries was significantly increased in the high-salt offspring whereas Nox1 showed no changes. The local renin-angiotensin system in mesenteric arteries was activated, associated with an increased NADPH oxidase. DNA methylation at the proximal promoter of angiotensin-converting enzyme gene in the lung was significantly increased in the high-salt offspring (P = 0.004).

CONCLUSION

The results suggest that prenatal high-salt diet impairs nitric oxide-mediated vasodilatation because of the increased oxidative stress-affected renin-angiotensin system in the high-salt offspring, providing new information for understanding, and early prevention of cardiovascular diseases in fetal origins.

S-adenosyl methionine regulates calcium channels and inhibits uterine smooth muscle contraction in rats with infectious premature delivery through the transient receptor protein 3/protein kinase Cβ/C-kinase-activated protein phosphatase-1 inhibitor of 17 kDa signaling pathway

The aim of the present study was to investigate the effects of S-adenosyl methionine (SAMe) on infectious premature inflammatory factors and uterine contraction, and to further explore its mechanism of action via the transient receptor protein 3 (TRPC3)/protein kinase Cβ (PKCβ)/C-kinase-activated protein phosphatase-1 inhibitor of 17 kDa (CPI-17) signaling pathway, following intervention by a TRPC3 inhibitor. A rat model of premature delivery induced by lipopolysaccharide (LPS) was established. Following treatment with SAMe and inhibiting TRPC3 expression, rat serum and uterus were isolated. Hematoxylin and eosin staining was used to observe the histopathological changes in the uterus. Uterine muscle strips in vitro were selected to measure the changes in muscle tension. ELISA was utilized to measure the changes in serum inflammatory factor and oxidative stress indexes. Immunohistochemistry, western blot assay and reverse transcription-quantitative polymerase chain reaction were applied to detect calcium channel protein expression in the uterus. Western blot analysis was employed to measure the expression of TRPC3/PKCβ/CPI-17 signaling pathway-related proteins. TRPC3 was highly expressed in the uterus of rat models of premature delivery induced by LPS. Following treatment with SAMe, inflammatory cell infiltration markedly reduced in the uterus and the tension of in vitro uterine muscle strips significantly decreased. SAMe treatment suppressed inflammatory reaction and oxidative stress, and diminished L-type and T-type calcium channel protein expression. TRPC3/PKCβ/CPI-17 signaling pathway-related protein expression was also reduced. When TRPC3 expression was suppressed, the effects of SAMe against inflammation and oxidative stress were diminished. TRPC3/PKCβ/CPI-17 signaling pathway-related protein expression significantly increased. SAMe was able to reduce inflammatory reaction and oxidative stress in the uterus of rat model of infectious premature delivery induced by LPS, prolong delivery time, reduce the mortality rate of offspring rats, and serve a therapeutic role. This effect is likely achieved via the regulation of uterine contractions and childbirth through the TRPC3/PKCβ/CPI-17 signaling pathway.

Maternal high-salt diet alters redox state and mitochondrial function in newborn rat offspring's brain

Excessive salt intake is a common feature of Western dietary patterns, and has been associated with important metabolic changes including cerebral redox state imbalance. Considering that little is known about the effect on progeny of excessive salt intake during pregnancy, the present study investigated the effect of a high-salt diet during pregnancy and lactation on mitochondrial parameters and the redox state of the brains of resulting offspring. Adult female Wistar rats were divided into two dietary groups (n 20 rats/group): control standard chow (0·675 % NaCl) or high-salt chow (7·2 % NaCl), received throughout pregnancy and for 7 d after delivery. On postnatal day 7, the pups were euthanised and their cerebellum, hypothalamus, hippocampus, prefrontal and parietal cortices were dissected. Maternal high-salt diet reduced cerebellar mitochondrial mass and membrane potential, promoted an increase in reactive oxygen species allied to superoxide dismutase activation and decreased offspring cerebellar nitric oxide levels. A significant increase in hypothalamic nitric oxide levels and mitochondrial superoxide in the hippocampus and prefrontal cortex was observed in the maternal high-salt group. Antioxidant enzymes were differentially modulated by oxidant increases in each brain area studied. Taken together, our results suggest that a maternal high-salt diet during pregnancy and lactation programmes the brain metabolism of offspring, favouring impaired mitochondrial function and promoting an oxidative environment; this highlights the adverse effect of high-salt intake in the health state of the offspring.

Roles and mechanisms of TRPC3 and the PLCγ/PKC/CPI-17 signaling pathway in regulating parturition

The aim of the current study was to investigate the role of phospholipase C (PLC)γ/protein kinase C (PKC)/C-kinase-activated protein phosphatase-1 (CPI-17) signaling pathways in uterine smooth muscle during parturition. Samples of uterine tissue were collected from pregnant patients who underwent a caesarean section for preterm delivery, full-term delivery with labor onset, full-term delivery without labor onset, and from a non-pregnant control group undergoing surgery for cervical intraepithelial neoplasia III. Immunohistochemistry, and western blotting were used to assess the association between TRPC3 levels and parturition and the influence of calcium ion channels. In addition, pregnant mice were used to explore the effect of uterine canonical transient receptor potential 3 (TRPC3) expression on the parturition-triggering mechanism and PLCγ/PKC/CPI-17 signaling pathways. Pregnant mouse uterine smooth muscle cells were cultivated, with and without TRPC3 silencing, and the expression levels of PLCγ, PKC and CPI-17, the upstream and downstream factors of the TRPC3 pathway, were measured in pregnant mouse uterine smooth muscle cells, in order to provide a theoretical basis for the prevention and treatment of premature labor. In the preterm and full-term without labor onset patient groups, the TRPC3 gene expression in the mSMCs was significantly overexpressed when compared with the non-pregnant group (P<0.05); however, TRPC3 expression was not elevated in the full-term with labor onset group, exhibiting no significant difference compared with the non-pregnant group (P>0.05). During pregnancy, compared with the non-pregnant controls, Ca_v1.2, Ca_v3.1 and Ca_v3.2 gene expression levels were markedly increased (P<0.05) in mSMCs from the preterm delivery group and the full-term with labor onset group, however were non-significantly increased in the full-term without labor onset group. The level of TRPC3 was highest in the preterm group, while the levels of Ca_v1.2, Ca_v3.1 and Ca_v3.2 were highest in the full-term with labor onset group. In the preterm, LPS-treated preterm and full-term groups, TRPC3, MAPK, ERK1/2, P-ERK, Ca_v3.2, Ca_v3.1 and Ca_v1.2 were all expressed at higher levels than in the unfertilized group. In the LPS-treated preterm group, the levels of TRPC3, MAPK, ERK1/2, P-ERK, Ca_v3.2, Ca_v3.1 and Ca_v1.2 were increased compared with the preterm group. Furthermore, following transfection of small interfering TRPC3 (siTRPC3) into cells, it was demonstrated that the levels of TRPC3, PLCγ, PKC, CPI-17, P-CPI-17, Ca_v1.2, Ca_v3.1 and Ca_v3.2 expression were lower in the LPS siTRPC3 group when compared with that of the LPS-treated untransfected control group.

Prenatal Hypoxia Induced Dysfunction in Cerebral Arteries of Offspring Rats

BACKGROUND

Hypoxia during pregnancy could cause abnormal development and lead to increased risks of vascular diseases in adults. This study determined angiotensin II (AII)-mediated vascular dysfunction in offspring middle cerebral arteries (MCA).

METHODS AND RESULTS

Pregnant rats were subjected to hypoxia. Vascular tension in offspring MCA by AII with or without inhibitors, calcium channel activities, and endoplasmic reticulum calcium stores were tested. Whole-cell patch clamping was used to investigate voltage-dependent calcium channel currents. mRNA expression was tested using quantitative real-time polymerase chain reaction. AII-mediated MCA constriction was greater in male offspring exposed to prenatal hypoxia. AT1 and AT2 receptors were involved in the altered AII-mediated vasoconstriction. Prenatal hypoxia increased baseline activities of L-type calcium channel currents in MCA smooth muscle cells. However, calcium currents stimulated by AII were not significantly changed, whereas nifedipine inhibited AII-mediated vasoconstrictions in the MCA. Activities of IP3/ryanodine receptor-operated calcium channels, endoplasmic reticulum calcium stores, and sarcoendoplasmic reticulum membrane Ca2+-ATPase were increased. Prenatal hypoxia also caused dysfunction of vasodilatation via the endothelium NO synthase. The mRNA expressions of AT1A, AT1B, AT2R, Cav1.2α1C, Cav3.2α1H, and ryanodine receptor RyR2 were increased in the prenatal-hypoxia group.

CONCLUSIONS

Hypoxia in pregnancy could induce dysfunction in both contraction and dilation in the offspring MCA. AII-increased constriction in the prenatal-hypoxia group was not mainly dependent on the L-type and T-type calcium channels; it might predominantly rely on the AII receptors, IP3/ryanodine receptors, and the endoplasmic reticulum calcium store as well as calcium ATPase.

Maternal high salt diet altered Adenosine-mediated vasodilatation via PKA/BK channel pathway in offspring rats

SCOPE

High salt (HS) diets are related to cardiovascular diseases, and prenatal HS was suggested to increase risks of coronary artery diseases in the offspring. This study tested the hypothesis that prenatal HS may influence Adenosine-induced vasodilatation via protein kinase A (PKA) pathway in coronary arteries.

METHODS AND RESULTS

Sprague-Dawley rats were fed with 8% salt diet for gestation, the control was fed with 0.3% salt diet. Coronary arteries from male adult offspring were tested for K⁺ channels and Adenosine signal pathways. Adenosine-mediated vasodilatation was reduced in coronary arteries in HS. There was no difference in gene expression of A_2A receptors between the two groups. After pretreatment with PKA inhibitor, vasodilatation to Adenosine was decreased to a smaller extent in HS than that in control. Forskolin (activator of adenylate cyclase)-mediated vasodilatation was decreased in HS. Iberiotoxin (large-conductance Ca²⁺ -activated K⁺ channel [BK channel] inhibitor) attenuated Forskolin-induced vasodilatation in control, not in HS group. Currents of BK channels decreased in coronary artery smooth muscle cells, and PKA-modulated BK channel functions were declined. Protein levels of BK β1 and PKA C-subunits in coronary arteries of HS offspring were reduced.

CONCLUSIONS

Prenatal HS diets altered Adenosine-mediated coronary artery vasodilatation in the offspring, which was linked to downregulation of cAMP/PKA/BK channel pathway.