Acute administration of pioglitazone attenuates morphine withdrawal syndrome in rat: a novel role of pioglitazone.

BACKGROUND: Long-term exposure to opiates such is morphine induces dependence. PURPOSE: The purpose of the present study was to investigate the effects of the acute administration of pioglitazone, a selective agonist of peroxisome proliferator activated receptors gamma (PPAR-γ), on the morphine withdrawal syndrome in the rat. METHODS: Male Wistar rats (200-250 g) were selected randomly and divided into 8 groups including 2 non-dependent groups and 6 morphine-dependent groups which were received additive doses of morphine subcutaneously at an interval of 12 h for 9 continuous days. On the ninth day, only the morning dose of morphine was injected and 2 h later, morphine withdrawal was precipitated by naloxone and then ten distinct withdrawal behaviors were recorded for 45 min. Pioglitazone (5, 10, 20 and 40 mg/kg) was gavaged 2 h before naloxone injection. It is worth noting that 1 h before the pioglitazone (40 mg/kg) gavage, GW-9662 (2 mg/kg), a selective PPAR-γ antagonist, was administrated in order to evaluate the possible role of the PPAR-γ. RESULT AND DISCUSSION: The results of this study showed that administration of pioglitazone (40 mg/kg) decreased all withdrawal signs and the statistical analysis indicated that pioglitazone could attenuate the total withdrawal scores significantly. Administration of GW-9662 had no significant effect on pioglitazone attenuation effect on morphine withdrawal symptoms.Taking together, it was concluded that acute oral administration of pioglitazone prevented naloxone-precipitated withdrawal symptoms and GW-9662 could not revert its effect on morphine withdrawal syndrome. It seems that pioglitazone suppresses morphine withdrawal syndrome through PPAR-γ independent mechanisms.

The effects of Ramadan fasting on endothelial function in patients with cardiovascular diseases.

BACKGROUND/OBJECTIVES: Endothelial dysfunction, which can be manifested by loss of nitric oxide bioavailability, is an increasingly recognized cause of cardiovascular diseases. Previous studies showed that diets affect endothelial function and modify cardiovascular risks. This study aimed to assess the effects of Ramadan fasting, as a diet intervention, on endothelial function. SUBJECTS/METHODS: The study population consisted of 21 male patients (mean age: 52±9 years) with cardiovascular risks (coronary artery disease, cerebrovascular or peripheral arterial diseases). The biochemical variables in serum of patients were measured 2 days before and after Ramadan fasting. The levels of asymmetric dimethylarginine (ADMA) and vascular endothelial growth factor (VEGF) were evaluated using the enzyme-linked immunosorbent assay. Nitric oxide (NO) and Malondialdehyde (MDA) levels were measured by the Griess and thiobarbituric acid reaction substances assay, respectively. RESULTS: NO levels in patients after Ramadan fasting were significantly higher compared with the baseline value (85.1±11.54 vs 75.8±10.7 µmol/l) (P<0.05). Post-Ramadan levels of ADMA decreased significantly in comparison with pre-Ramadan levels (802.6±60.9 vs 837.6±51.0 nmol/l) (P<0.05). In addition, the levels of VEGF and MDA changed during Ramadan fasting, but these changes were not statistically significant (228.1±27.1 vs 222.7±22.9 pg/ml and 3.2±0.7 vs 3.6±1.1 µmol/l, respectively). CONCLUSIONS: Ramadan fasting may have beneficial effects on endothelial function and can modulate cardiovascular risks. Further studies are needed to confirm the clinical significance of Ramadan fasting on cardiovascular health.

Duloxetine attenuated morphine withdrawal syndrome in the rat.

BACKGROUND: Long term exposure to morphine can induce dependence. The exact mechanisms of dependence are not yet fully understood. Many studies have been conducted to find new drugs that can prevent dependence. This study examined the effects of the chronic administration of duloxetine on the morphine withdrawal syndrome in rats. METHODS: To this end, male Wistar rats (170-220 g) were randomly divided into 5 groups including one saline treated group (non-depend­ent group) and 4 morphine dependent groups. The experimental groups received additive doses of morphine for 9 days in order to induce dependence according to the following protocol: day 1:5 mg/kg/12 h, days 2 and 3: 10 mg/kg/12 h, days 4, 5:15 mg/kg/12 h, days 6 and 7: 20 mg/kg/12 h and days 8 and 9: 25 mg/kg/12 h. On the ninth day, the morning dose of morphine was only injected. It is worth noting that 30 min before the morning dose of morphine, duloxetine (10, 20, and 40 mg/kg) was injected intraperitoneally. In addition, 2 h after the last injection of morphine, the morphine withdrawal was precipitated by naloxone. The withdrawal signs were recorded for 30 min; these signs included jumping, rearing, genital grooming, abdominal writhing, wet dog shaking, and teeth grinding. RESULTS: The results of the study revealed that the chronic administration of duloxetine decreased all the withdrawal signs. Besides, it attenuated the total withdrawal scores significantly. CONCLUSION: Results indicate that the regulatory effects on serotonergic and noradrenergic parameters might be associated with the amelioration of the withdrawal symptoms.

Serum concentrations and hypoglycemic effect of gliclazide: crosspovidone solid dispersion on streptozotocin induced diabetic rats.

Gliclazide is practically insoluble in water and its GI absorption is limited by its dissolution rate. Our previously published works indicated that preparing gliclazide-crosspovidone solid dispersion in the drug/ carrier ratio of 1:1 using cogrinding technique is able to enhance drug dissolution rate. The coground of gliclazide-crosspovidone was administrated to the rats and the hypoglycemic effects of pure drug, a physical mixture and the coground were considered in 3 groups of rats weighing 200-250 g (n=6). The rats were made diabetic by single intravenous administration of streptozotocin (60 mg/kg). Each of the rats received a single dose of gliclazide (equivalent to 40 mg/kg) as pure drug, physical mixture and coground in an aqueous suspension. Glucose level was assessed via glucometer after collecting the blood samples from tail vein. Gliclazide concentration in plasma was assessed applying high pressure liquid chromatography. According to 1-way ANOVA, Student-Newman-Keuls test, the coground revealed enhanced hypoglycemic effects as well as higher serum gliclazide concentration relative to pure drug and its corresponding physical mixture in the all sampling times. The area under serum glucose concentration curve vs. time for the pure gliclazide, physical mixture and coground formulations were 3 090.5±79, 3 018.8±96 and 2 374.0±73 mg.h/dl, respectively. Correspondingly, their area under serum gliclazide concentration curve vs. time were 1 171.8±156.8, 1 379.5±96.2 and 4 827.7±637.5 µg.h/ml. It follows that; formulation of gliclazide-crosspovidone coground is able to improve oral absorption of the drug.