G. Díaz de Barboza

New perspectives in melatonin uses

This review summarizes the metabolism, secretion, regulation and sites of action of melatonin. An updated description of the melatonin receptors, including their signal transduction mechanisms, distribution and characterization of receptor genes, is given. Special emphasis is focused on the clinical aspects and potential uses of melatonin in the sleep-wake rhythms, in the immune function, in cancer therapy, in neuroprotection against oxidative damage and antioxidant activities in different tissues. Finally, combined effects of melatonin with other drugs are discussed.

Sodium deoxycholate alters the transcellular pathway of intestinal calcium absorption

Diabetes mellitus (DM) type I is a disorder characterized by hyperglycemia due to a deficient insulin secretion. Alterations in different organs have been observed in DM. The aim of this work was to study intestinal calcium absorption, alkaline phosphatase (AP) activity and the expression of some genes involved in calcium transport in an experimental diabetes model. Two-month old male Wistar rats were divided into two groups: control (n=5) and treated rats (n=5). Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) (60 mg/kg) after fasting for 12-hours. Control rats were injected with the vehicle. Serum and urine glucose were determined before and 5 days after STZ induction. Rats with glycemia over 250 mg/dL were considered diabetic. Intestinal calcium absorption was measured and AP activity from duodenal mucosa was assayed. Ca-ATPase pump and calbindin D28K gene expressions were analyzed by RT-PCR. The weight of the STZ-injected rats decreased after 5 days of the induction and the glucose levels were significantly higher than those of the control group (406±13 mg/dL vs 142±17 mg/dL, p<0.001). Diabetic rats had polyuria and glycosuria. Calcium absorption was lower in diabetic rats than in controls (0.26±0.01 nmol Ca/mL plasma vs 0.65±0.05 nmol Ca/mL plasma, p<0.001). AP activity was significantly lower in diabetic rats than in controls (0.31±0.06 IU/mg protein vs 0.59±0.10 IU/mg protein, p<0.05). Preliminary determinations show that the expression of the studied genes would be similar in both groups. To conclude, the metabolic alteration in DM would alter intestinal calcium absorption and AP activity. The molecular mechanisms responsible of these effects are under investigation. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.