Esculin reduces P2X7 and reverses mitochondrial dysfunction in the renal cortex of diabetic rats.

AIMS: To evaluate the effects of esculin treatment on P2X7 receptor and mitochondrial dysfunction in the renal cortex of diabetic rats. MAIN METHODS: Male Wistar rats, 7 weeks old, were unilaterally nephrectomized. Part of these animals were induced to diabetes using streptozotocin (60 mg/kg). Diabetes was confirmed 48 h after induction, with blood glucose levels ≥200 mg/dL. Part of control and diabetic animals were selected to receive daily doses of esculin (50 mg/kg), during 8 weeks. The animals were placed in metabolic cages at the eighth week of protocol for 24 h urine collection and a small aliquot of blood was collected for biochemical analysis. After this procedure, the animals were euthanized and the remaining kidney was stored for histopathological analysis, Western blotting and mitochondrial high-resolution respirometry. KEY FINDINGS: Although esculin did not change metabolic parameters, renal biochemical function, neither TBARS in DM rats, esculin reduced P2X7 levels in these animals and restored mitochondrial function via glycolysis substrates and ß-oxidation. Besides, at the histological analysis, we observed that esculin reduced inflammatory infiltrates and collagen IV deposits as compared to diabetic group. SIGNIFICANCE: Esculin attenuated the development of renal injuries caused by hyperglycemia, proinflammatory and oxidative mechanisms mediated by P2X7 receptor, as seen by histological findings and improved mitochondrial function in diabetic animals. This suggests that esculin could be used as an adjuvant therapy to prevent the diabetic nephropathy.

Inhibition of the P2X7 receptor improves renal function via renin-angiotensin system and nitric oxide on diabetic nephropathy in rats.

AIM: To evaluate the effects of P2X7 receptor blockade on renin-angiotensin system (RAS) in rats with diabetic nephropathy (DN). MAIN METHODS: Wistar rats were unilaterally nephrectomized and received streptozotocin for diabetes mellitus (DM) induction; control animals (CTL) received the drug vehicle. The animals were submitted to P2X7 receptor silencing, forming the group (DM + siRNA). The animals were placed in metabolic cages for data collection and evaluation of renal function; at the end of the protocol, the kidney was removed for analysis of P2X7, renin, angiotensin-converting enzyme (ACE), ACE2, angiotensin, thiobarbituric acid reactive substance levels (TBARS), nitric oxide (NO) and qualitative histological. KEY FINDINGS: The metabolic profile was attenuated in DM + siRNA vs. DM and there was a significant improvement in creatinine, urea and proteinuria levels in the same group. Renin expression was significantly decreased in DM + siRNA vs. DM. ACE and ACE2 were significantly reduced in DM + siRNA vs. DM. TBARS levels were decreased and NO showed an increase in DM + siRNA vs. DM, both significant. All histological alterations were improved in DM + siRNA vs. DM. SIGNIFICANCE: Data have shown that although silencing of the P2X7 receptor did not decrease fasting glucose, it promoted an improvement in the metabolic profile and a significant recovery of renal function, revealing a protective action by the inhibition of this receptor. This effect must have occurred due to the inhibition of RAS and the increase of NO, suggesting that the use of P2X7 receptors inhibitors could be used as adjuvant therapy against DN progression.

Monolithic triglyceride matrices: a controlled-release system for proteins.

Matrices made of glyceryl trimyristate as a bioerodible and biocompatible material were manufactured by compression in dimensions that would still allow an application via injection. Pyranine, as a low molecular hydrophilic compound with a low detection limit, and tetramethylrhodamine labeled bovine serum albumin (TAMRA-BSA), as a high molecular weight (66 kDa) protein compound, served as model drugs for release investigations. In vitro studies with pyranine revealed that release depends substantially on the gelatin content of the matrices, which proved to be a useful tool as a release modifier. The duration of the drug release period can be adjusted to a desired time interval ranging from days to weeks by choosing the right gelatin content. Moreover, results illustrated the importance of the molecular weight and the nature of the compound to be incorporated into such matrices, since investigations with TAMRA-BSA showed a more pronounced burst release and altered release profiles and periods. Experiments with hyaluronidase, which served as a model enzyme to assess the problem of protein integrity in such matrices, suggested that proteins may display sufficient stability during the manufacturing procedure of the cylinders or while in contact with the triglyceride matrices. In addition to in vitro investigations, a study in mice revealed that after 15 days of subcutaneous implantation the matrices showed a good in vivo stability. The main conclusion that could be drawn from these results was that triglycerides are a promising alternative to biodegradable polymers for the development of parenteral release systems for protein and peptide drugs.