Analysis of salivary flow rate, biochemical composition, and redox status in orchiectomized spontaneously hypertensive rats

OBJECTIVE

This study aimed to analyze the salivary flow rate, biochemical composition, and redox status in orchiectomized spontaneously hypertensive rats (SHR) compared to normotensive Wistar rats.

DESIGN

Thirty-two young adult male SHR and Wistar (3-months-old) rats were randomly distributed into four groups; either castrated bilaterally (ORX) or underwent fictitious surgery (SHAM) as Wistar-SHAM, Wistar-ORX, SHR-SHAM, and SHR-ORX. Two months beyond castration, pilocarpine-induced salivary secretion was collected from 5-month-old rats to analyze salivary flow rate, pH, buffer capacity, total protein, amylase, calcium, phosphate, sodium, potassium, chloride, thiobarbituric acid reactive substances (TBARs), carbonyl protein, nitrite, and total antioxidant capacity.

RESULTS

The salivary flow rate was higher in the Wistar-ORX compared to the Wistar-SHAM group, while remaining similar between the SHR-SHAM and SHR-ORX groups. ORX did not affect pH and salivary buffer capacity in both strains. However, salivary total protein and amylase were significantly reduced in the Wistar-ORX and SHR-ORX compared to the respective SHAM groups. In both ORX groups, salivary total antioxidant capacity and carbonylated protein were increased, while lipid oxidative damage (TBARs) and nitrite concentration were higher only in the Wistar-ORX than in the Wistar-SHAM group. In the Wistar-ORX and SHR-ORX, the salivary calcium, phosphate, and chloride were increased while no change was detected in the SHAM groups. Only salivary buffering capacity, calcium, and chloride in the SHR-ORX adjusted to values similar to Wistar-SHAM group.

CONCLUSION

Hypertensive phenotype mitigated the orchiectomy-induced salivary dysfunction, since the disturbances were restricted to alterations in the salivary biochemical composition and redox state.

Decreased reactive oxygen species production and NOX1, NOX2, NOX4 expressions contribute to hyporeactivity to phenylephrine in aortas of pregnant SHR

AIMS

We determined whether decreased reactive oxygen species (ROS) production in the aorta of pregnant spontaneously hypertensive rats (SHR) resulted in increased nitric oxide (NO) bioavailability and hyporeactivity to phenylephrine (PE).

MAIN METHODS

Systemic and aortic oxidative stress were measured in pregnant and non-pregnant Wistar rats and SHR. Furthermore, the hypotensive effects of apocynin (30 mg/kg) and Tempol (30 mg/kg) were analyzed. Intact aortic rings of pregnant and non-pregnant rats were stimulated with PE in the absence of or after incubation (30 min) with apocynin (100 μmol/L). The effect of apocynin on the concentrations of NO and ROS were measured in aortic endothelial cells (AEC) using DAF-2DA (10 mmol/L) and DHE (2.5 mmol/L), respectively. Western blotting was performed to analyze eNOS, NOX1, NOX2, NOX4 and SOD expression. ROS production was analyzed by the lucigenin chemiluminescence method.

KEY FINDINGS

Aortic oxidative stress and ROS concentration in AEC were reduced in pregnant Wistar rats and SHR, when compared to non-pregnant rats. ROS production and NOX1, NOX2 and NOX4 expression in the aortas were decreased in pregnant SHR, but not in pregnant Wistar rats. Increased eNOS expression in aortas and NO concentration in AEC were observed in pregnant Wistar rats and SHR. Apocynin reduced PE-induced vasoconstriction in the aortas of non-pregnant Wistar rats and SHR, and pregnant Wistar rats, but not in the aortas of pregnant SHR.

SIGNIFICANCE

Taken together, these results suggest that ROS production was decreased in the aortas of pregnant SHR and could contribute to higher NO bioavailability and hyporeactivity to PE in the aortas of pregnant SHR.