Effects of long-term oral administration of melatonin on tear production, intraocular pressure, and tear and serum melatonin concentrations in healthy dogs.

OBJECTIVE: To evaluate the effects of long-term (30-day) oral administration of melatonin on tear production, intraocular pressure (IOP), and concentration of melatonin in the tears and serum of healthy dogs. ANIMALS: 20 healthy sexually intact adult male dogs. PROCEDURES: 10 dogs were given melatonin (0.3 mg/kg, PO, q 24 h, administered in food at 9 am), and 10 dogs were given a placebo. Tear and serum melatonin concentrations, IOP, and tear production (determined with a Schirmer tear test) were recorded before (baseline) and 30 minutes, 3 hours, and 5 hours after administration of melatonin or the placebo on day 1 and 30 minutes after administration of melatonin or the placebo on days 8, 15, and 30. RESULTS: Data collection time had significant effects on tear production, IOP, and tear melatonin concentration but not on serum melatonin concentration. Treatment (melatonin vs placebo) had a significant effect on tear melatonin concentration, but not on tear production, IOP, or serum melatonin concentration; however, tear melatonin concentration was significantly different between groups only 30 minutes after administration on day 1 and not at other times. CLINICAL RELEVANCE: In healthy dogs, long-term administration of melatonin at a dosage of 0.3 mg/kg, PO, every 24 hours did not have any clinically important effects on tear production, IOP, or serum or tear melatonin concentrations.

Role of Schwann Cells in Preservation of Retinal Tissue Through Reduction of Oxidative Stress.

The aim of this study was to evaluate the effect of subretinal injection of Schwann cells on preservation of retina by decreasing oxidative stress in Dystrophic Royal College of Surgeons (RCS) rats. Schwann cells were harvested from the sciatic nerve of postnatal day 5, RCS rats. Twenty-five RCS rats randomly assigned to cell and sham groups. Schwann cells injected in the sub-retinal space in one eye of the cell group and carrier medium was injected in one eye of the sham group. The proof for the appropriate site of injection of Schwann cells confirmed by the green fluorescent protein (GFP) positive cells. Electroretinogram (ERG) and enucleation for histopathology and enzymatic evaluation were performed 1, 2 and 3 months post-injection. The enzymatic evaluation included catalase, superoxide dismutase (SOD) and glutathione peroxidase 1 (GPx1) by enzyme-linked immunosorbent assay (ELISA) method. Three months after injection, histopathology assessments showed a complete absence of the outer nuclear layer (ONL), photoreceptors and obvious reduction of retinal pigment epithelium (RPE) in the sham group. Cell group showed marked preservation of RPE, choroidal congestion and mild presence of ONL. The green fluorescent protein positive Schwann cells remained in one integrated layer during the study under RPE. The enzymatic evaluation showed that in cell group expression of SOD and GPx1 until month 2 and catalase until month 1 were significantly more than the sham group. At the end of month 3, the amplitude of ERG waves significantly preserved in cell group in comparison to baseline waves and the sham group. We concluded that Schwan cells are able to preserve retinal in RCS rats by reducing oxidative stress.

Molecular approaches in obesity studies.

The prevalence of obesity as one of the most health concerns has increased globally. This kind of disease has been accounted for several diseases such as type 2 diabetes, different types of cancer, heart disease, and Alzheimer. Obesity is a multifactorial disease that both environmental factors and genetics play important role in its susceptibly. In molecular biology, characterization of the adipocyte secretome is important in signaling to other organs and in regulating energy balance for evaluating underlines mechanism. Since better understanding of this disease lead to both preventive and post treatment of obesity which is achieved by molecular evaluations, this review underlies the importance of some molecular approaches in the field of obesity.