Losartan may prevent the elevation of plasma glucose, corticosterone and catecholamine levels induced by chronic stress

Introduction

Stress is a stimulus that activates the hypothalamic pituitary adrenal (HPA) axis and sympathetic nervous system (SNS). Increased activity of the SNS causes to increment or impairment in blood pressure, heart rate, body temperature and plasma glucose and adrenocorticotrophic hormone (ACTH) levels. Angiotensin II (Ang II), which is a product of the renin-angiotensin system (RAS), is an important factor affecting the activity of the SNS and responses to stress. We suggest that the blockade of Ang II may be worthwhile in the prevention and treatment of diabetes mellitus and cardiovascular diseases affected by stress. Therefore, we investigated the effects of immobilisation stress on blood glucose, norepinephrine (NE), epinephrine (E) and corticosterone levels and the effects of an Ang II receptor antagonist, losartan, on these parameters.

Materials and methods

The rats were kept in small cylindrical cages for 60 min/day for 10 consecutive days to perform chronic immobilisation stress. Losartan (10 mg/kg) was given daily by gavage to Losartan (L) and Losartan + Chronic Stress (L+CS) groups. Control (C) and Chronic Stress (CS) P groups received an equal volume of saline daily by gavage for 10 days. After the last stress regimen, blood samples were collected for plasma glucose, NE, E and corticosteroid measurements.

Results

Plasma glucose, NE, E and corticosterone levels in the CS Group increased significantly compared with the C group. In Group L+CS, the plasma glucose, NE, E and corticosterone levels decreased significantly vs. Group CS. In Group L there was no significant difference vs. Group C.

Conclusion

It can be speculated that chronic blockade of RAS may decrease the excess sympathetic responses to stress in cardiovascular diseases and prevent the likely development of Type II diabetes mellitus.

Combined impact of matrix metalloproteinase-3 and paraoxonase 1 55/192 gene variants on coronary artery disease in Turkish patients

BACKGROUND

We investigated the association of matrix metalloproteinase-3 (MMP-3) and paraoxonase 1 (PON1) 55/192 polymorphisms with coronary artery disease (CAD) and the number of diseased vessels in patients with CAD.

MATERIAL/METHODS

One hundred thirty-nine CAD patients and 119 healthy control subjects were included in the study. Genotypes for PON1 55/192 and MMP-3 5A/6A polymorphisms were determined by restriction fragment length polymorphism.

RESULTS

Although distributions of the RR genotype of PON1 192 and the 5A5A genotype of MMP-3 were more frequent in patients, frequencies of the QQ genotype of PON1 192, the MM genotype of PON1 55, and the 6A6A genotype of MMP-3 were significantly lower in patients compared with healthy control subjects. The combined genotypes of RR/LL and/or 5A5A are increased the risk of CAD when compared with subjects who possess neither the MMP-3 5A5A nor the PON1 RR/LL genotype. While the MMP-3 5A/6A genetic variants were not associated with the number of diseased vessels, PON1 55/192 variants were associated with the number of diseased vessels.

CONCLUSIONS

The combined PON1 55/192 and MMP-3 5A/6A genetic variants are associated with CAD; PON1 seems to be connected with the number of diseased vessels, and hypertension and hyperlipidemia are related with PON1 192 and MMP-3 in CAD patients.

ACE gene polymorphism in peripheral vascular disease

Peripheral vascular disease is an atherosclerotic process. It has been suggested that angiotensin converting enzyme insertion/deletion polymorphism is associated with atherosclerosis. The aim of this study was to investigate the role of the insertion/deletion polymorphism of the angiotensin-converting enzyme in Turkish patients with peripheral vascular disease in Western part of Turkey. We also investigated the relationship between serum angiotensin converting enzyme activity and distribution of genotypes in both patients and control group. The study group consisted of 78 patients with peripheral vascular disease. The control group consisted of 73 healthy adults. Serum angiotensin converting enzyme activities in patients were higher than those of the control group (p<0.05). Angiotensin converting enzyme genotype frequencies in patients were observed as 28.2%, 18% and 53.8% for DD, II and ID polymorphism, respectively. These frequencies in controls were 42.5%, 20.5% and 37% for DD, II and ID, respectively. Serum angiotensin converting enzyme activities in both groups with II genotype were significantly lower than those with ID and DD genotype (p<0.05). Although conflicting results have been reported about this polymorphism in patients with peripheral vascular disease, we suggest that the angiotensin converting enzyme ID genotype may be a risk factor for peripheral vascular disease.

Age-dependent changes in liver ganglioside levels

Gangliosides, sialic acid-containing glycosphingolipids, are found in the outer layer of the plasma membrane of all vertebrate tissue cells; the highest concentration is in the central nervous system. In recent years, there has been research on the distribution and quantity of gangliosides in extra-neuronal tissues, such as liver, kidney and intestine. Since liver is the main source of gangliosides that are carried by lipoproteins in the blood, we examined the effect of development and aging on gangliosides in liver tissue. The relationship was investigated between GM1, GD3, GD1a, GD1b, GT1b ganglioside fractions and the aging process in liver tissue of Wistar-Albino rats aged 3, 6, 12 and 24 months. HPLC analysis of liver gangliosides showed the following results: Compared to 3 month-old rats, the GM1 fraction was decreased by 50% in 6 month-old rats, increased in 12 month-old rats and decreased in 24 month-old rats. The GD3 and GD1b fractions increased until 12 months of age and were decreased significantly (p < 0.01) in 24 month-old rats. The GD1a ganglioside fraction was significantly increased in 6 and 24 month-old rats (p < 0.01). We concluded that the increment of the polar fractions, such as GD3 and GD1b, and the variations of the other fractions in the plasma membrane of the hydrophilic liver tissue during the first 12 months were important parameters.