Prepro-orexin mRNA expression in the rat brain is increased during pregnancy.

The purpose of this study was to investigate whether orexin expression in the rat brain was changed during pregnancy. Brain samples were obtained from 5 nonpregnant rats and 10 pregnant rats (5; day 10 of gestation, and 5; day 20 of gestation). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed to investigate the expression of prepro-orexin mRNA and the housekeeping gene in the rat brain. The signals were quantified by the densitometric analysis. The distribution and expression of orexin-A and orexin-B were determined using immunohistochemistry. The ratio of the prepro-orexin mRNA expressions to the housekeeping gene expression in pregnant rat brain were significantly higher than that in nonpregnant control. There was no significant difference between prepro-orexin mRNA levels of day 10 and day 20 of gestation. Immunohistochemical staining for orexin-A and orexin-B was present in neurons within and around the lateral and posterior hypothalamic areas in both nonpregnant and pregnant rats. These results suggest that increased prepro-orexin mRNA levels at early gestational age in the maternal rat has a role on energy metabolism during pregnancy.

Effects of pravastatin on progression of glucose intolerance and cardiovascular remodeling in a type II diabetes model.

OBJECTIVES: We examined the effects of early treatment with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor pravastatin on the progression of glucose intolerance and cardiovascular remodeling in a model of spontaneously developing type II diabetes mellitus (DM), the Otsuka Long-Evans Tokushima Fatty (OLETF) rats. BACKGROUND: Clinical trials showed that pravastatin prevented new-onset DM in hypercholesterolemic patients, and that it was effective in prevention of cardiovascular events in diabetics. METHODS: The OLETF rats were treated with pravastatin (100 mg/kg/day) from 5 weeks of age and compared with age-matched untreated OLETF rats and normal Long-Evans Tokushima Otsuka (LETO) rats on serial oral glucose tolerance tests (OGTT) and Doppler echocardiography and on histopathological/biochemical analyses of the heart at 30 weeks. RESULTS: The OGTT revealed that 40% and 89% of untreated OLETF rats were diabetic at 20 and 30 weeks, respectively, but 0% and only 30%, respectively, were diabetic in the treated OLETF. Left ventricular diastolic function was found impaired from 20 weeks in untreated OLETF but remained normal in the treated-OLETF. The wall-to-lumen ratio and perivascular fibrosis of coronary arteries were increased in untreated-OLETF but were limited in the treated-OLETF at 30 weeks. Moreover, cardiac expressions of a fibrogenic growth factor, transforming growth factor-beta1 (TGF-beta1), and a proinflammatory chemokine, monocyte chemoattractant protein-1 (MCP-1), were increased in untreated-OLETF. However, in the treated-OLETF, overexpressions of TGF-beta1 and MCP-1 were attenuated, which was associated with overexpression of endothelial nitric oxide synthase (eNOS) (2.5-fold of control LETO). CONCLUSIONS: Early pravastatin treatment prevented cardiovascular remodeling in the spontaneous DM model by retarding the progression of glucose intolerance, overexpressing cardiac eNOS, and inhibiting overexpressions of fibrogenic/proinflammatory cytokines.

Lipopolysaccharide triggers late preconditioning against myocardial infarction via inducible nitric oxide synthase.

OBJECTIVE: The aim of this study was to investigate the role of inducible nitric oxide synthase (iNOS) as a trigger in lipopolysaccharide (LPS)-induced late preconditioning against myocardial infarction. METHODS: Rats were pretreated intraperitoneally with two different doses of LPS (0.5 or 2.5 mg/kg) or normal saline (control) 24 h prior to lethal myocardial ischemia. Subsequently, all rats were subjected to a sustained 30-min coronary occlusion followed by 180-min reperfusion. In the second study, total RNA and protein were extracted from myocardium of the control and LPS-treated rats (after 4, 6 and 24 h of treatment) for reverse transcription-polymerase chain reaction and Western blot analysis. RESULTS: In LPS (2.5 mg/kg, but not 0.5 mg/kg)-treated rats receiving no pharmacological intervention, the percentage of myocardial infarct within the area at risk and left ventricle was significantly reduced to 42+/-4 and 24+/-2% (P<0.01) compared with the control group. The cardioprotection was abolished by injection of dexamethasone (4 mg/kg x 2, i.p.) or the selective iNOS inhibitor aminoguanidine (300 mg/kg x 2, s.c.) before LPS treatment. The expression of iNOS mRNA and the iNOS protein significantly increased 4 and 6 h after administration of LPS (2.5 mg/kg), respectively. The increases in iNOS mRNA and protein were eliminated by dexamethasone. But the iNOS mRNA and protein were not detectable 24 h after administration of LPS (2.5 mg/kg). CONCLUSIONS: These data provide molecular and pharmacological evidence that LPS-induced late preconditioning against myocardial infarction is triggered by iNOS.