The effect of estrogen on serum nitric oxide concentrations in normotensive and DOCA Salt hypertensive ovariectomized rats

Thymoquinone Prevents Myocardial and Perivascular Fibrosis Induced by Chronic Lipopolysaccharide Exposure in Male Rats: - Thymoquinone and Cardiac Fibrosis

Objectives

Thymoquinone (TQ) is one of the active ingredients of herbal plants such as Nigella sativa L. (NS) which has beneficial effects on the body. The beneficial effects of TQ on the cardiovascular system have reported. This study aimed to investigate the effect of TQ on cardiac fibrosis and permeability, serum and tissue concentration of inflammatory markers and oxidative stress status in chronic lipopolysaccharide exposure in male rats.

Methods

Seventy male Wistar rats were randomly divided into five groups as follows: (1) control; (2) LPS (1 mg/kg/day); (3–5) LPS + TQ with three doses of 2, 5 and 10 mg/kg (n=14 in each group). After 3 weeks, serum and cardiac levels of IL-1β, TNF-α and nitric oxide (NO) metabolites, and cardiac levels of malondialdehyde (MDA), total thiol groups, catalase (CAT) and superoxide dismutase (SOD) activities, permeability of heart tissue (evaluated by Evans blue dye method) and myocardial fibrosis were determined, histologically.

Results

LPS administration induced myocardial and perivascular fibrosis and increased cardiac oxidative stress (MDA), inflammatory markers and heart permeability, while, reduced anti-oxidative enzymes (SOD and CAT) and the total thiol group. Administration of TQ significantly attenuated these observations.

Conclusion

TQ improved myocardial and perivascular fibrosis through suppression of chronic inflammation and improving oxidative stress status and can be considered for attenuation of cardiac fibrosis in conditions with chronic low-grade inflammation.

Interaction of central Angiotensin II and estrogen on systolic blood pressure in female DOCA-salt treated rats

Background:

There is a probable interaction of central angiotensin II (Ang II) and estrogen (Est) on blood pressure in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Therefore, in the present study, the interaction between Ang II and Est in ovariectomized (Ovx) and Sham rats that were treated with DOCA- salt was evaluated.

Materials and Methods:

The female rats were divided into 10 groups as follows: Sham, Ovx, Sham-DOCA, Ovx-DOCA, Sham-DOCA-estrogen (E), Ovx DOCA-E, Sham-DOCA-losartan (L), Ovx-DOCA-L, Sham–DOCA-L-E, and Ovx-DOCA-L-E. The Est groups received estradiol valerate (2 mg/kg; daily; subcutaneously (s.c)) for four weeks. Following that, several doses of Ang II (0.5, 5, 50, 500, 5000 ng/5 μl) were injected via the intracerebroventricular (i.c.v) route and the changes in systolic blood pressure (SBP) were evaluated. In the losartan groups, 200 μg losartan was injected (i.c.v) 15 minutes after the Ang II injection and the blood pressure was recorded. Treatment by DOCA was performed by removal of one kidney, injection of DOCA (45 mg/kg i.p), and adding of sodium chloride (NaCl) (1%) and potassium chloride (KCl) (0.1%) in the drinking water.

Results:

The SBP was increased by Ang II and this effect in DOCA-salt treated rat was higher than in the untreated groups. The effect of Ang II on SBP in groups that were treated with Est and L was lower than that in the DOCA-salt groups. Increase in SBP was strongly attenuated by Ang II in groups that were co-treated with both Est and L compared to the DOCA-treated rats. These results showed that Est significantly attenuated the effect of central Ang II on SBP in the DOCA-salt treated rats.

Conclusion:

We suggest that there are interactions between E and Ang II in the control of blood pressure in DOCA-salt treated rats.

Should there be sex-specific criteria for the diagnosis and treatment of heart failure?

All-cause mortality from cardiovascular disease is declining in the USA. However, there remains a significant difference in risk factors for disease and in mortality between men and women. For example, prevalence and outcomes for heart failure with preserved ejection fraction differ between men and women. The reasons for these differences are multifactorial, but reflect, in part, an incomplete understanding of sex differences in the etiology of cardiovascular diseases and a failure to account for sex differences in pre-clinical studies including those designed to develop new diagnostic and treatment modalities. This review focuses on the underlying physiology of these sex differences and provides evidence that inclusion of female animals in pre-clinical studies of heart failure and in development of imaging modalities to assess cardiac function might provide new information from which one could develop sex-specific diagnostic criteria and approaches to treatment.

Evidence against protective role of sex hormone estrogen in Cisplatin-induced nephrotoxicity in ovarectomized rat model

BACKGROUND

Cisplatin (CP) is an effective drug in cancer therapy to treat the solid tumors, but it is accompanied with nephrotoxicity. The protective effect of estrogen in cardiovascular diseases is well-documented; but its nephron-protective effect against CP-induced nephrotoxicity is not completely understood.

MATERIALS AND METHODS

Thirty ovarectomized Wistar rats were divided in to five groups. Groups 1-3 received different doses of estradiol valerate (0.5, 2.5 and 10 mg/kg/week) in sesame oil for 4 weeks, and at the end of week 3, a single dose of CP (7 mg/kg, intraperitoneal [IP]) was administrated. Group 4 (positive control) received the same regimen as group 1-3 without estradiol without vehicle. The negative control group (Group 5) received sesame oil during the study. The animals were sacrificed 1 week after CP injection for histopathological studies.

RESULTS

The serum level of blood urea nitrogen and creatinine, kidney tissue damage score (KTDS), kidney weight and percentage of body weight change in CP-treated groups significantly increased (P < 0.05), however, there were no significant differences detected between the estrogen-treated groups (Groups 1-3) and the positive control group (Group 4). Although, estradiol administration enhanced the serum level of nitrite, it was not affected by CP. Finally, significant correlation between KTDS and kidney weight was detected (r (2) = 0.63, P < 0.01).

CONCLUSION

Estrogen is not nephron-protective against CP-induced nephrotoxicity. Moreover, it seems that the mechanism may be related to estrogen-induced oxidative stress in the kidney, which may promote the nephrotoxicity.

Vitamin E, Vitamin C, or Losartan Is Not Nephroprotectant against Cisplatin-Induced Nephrotoxicity in Presence of Estrogen in Ovariectomized Rat Model

Background. The nephroprotective effect of vitamins E and C or losartan against cisplatin (CP)- induced nephrotoxicity when they are accompanied by estrogen was investigated. Methods. The ovariectomized rats received estradiol valerate for two weeks. At the end of the first week, a single dose of CP (7 mg/kg, IP) was also administered, and they received placebo (group 1), vitamin E (group 2), vitamin C (group 3), or losartan (group 4) every day during the second week, and they were compared with another three control groups. Results. CP alone increased the serum levels of blood urea nitrogen (BUN), creatinine (Cr), and kidney tissue damage score (KTDS), significantly (P < 0.05), however at the presence of estradiol and CP, vitamin C, vitamin E, or losartan not only did not decrease these parameters, but also increased them significantly (P < 0.05). The serum level of superoxidase dismutase (SOD) was reduced by CP (P < 0.05), but it was increased when estradiol or estradiol plus vitamin C or losartan were added (P < 0.05). Conclusion. The particular pharmacological dose of estrogen used in this study abolish the nephroprotective effects vitamins C and E or losartan against CP-induced nephrotoxicity.

Aqueous extract of tamarind seeds selectively increases glucose transporter-2, glucose transporter-4, and islets' intracellular calcium levels and stimulates β-cell proliferation resulting in improved glucose homeostasis in rats with streptozotocin-induced diabetes mellitus

Tamarindus indica Linn. has been in use for a long time in Asian food and traditional medicine for different diseases including diabetes and obesity. However, the molecular mechanisms of these effects have not been fully understood. In view of the multidimensional activity of tamarind seeds due to their having high levels of polyphenols and flavonoids, we hypothesized that the insulin mimetic effect of aqueous tamarind seed extract (TSE) might increase glucose uptake through improvement in the expression of genes of the glucose transporter (GLUT) family and sterol regulatory element-binding proteins (SREBP) 1c messenger RNA (mRNA) in the liver. Daily oral administration of TSE to streptozotocin (STZ)-induced (90 mg/kg intraperitoneally) type 2 diabetic male Wistar rats at different doses (120 and 240 mg/kg body weight) for 4 weeks showed positive correlation with intracellular calcium and insulin release in isolated islets of Langerhans. Tamarind seed extract supplementation significantly improved the GLUT-2 protein and SREBP-1c mRNA expression in the liver and GLUT-4 protein and mRNA expression in the skeletal muscles of diabetic rats. The elevated levels of serum nitric oxide (NO), glycosylated hemoglobin level (hemoglobin (A1c)) and tumor necrosis factor α (TNF-α) decreased after TSE administration. Immunohistochemical findings revealed that TSE abrogated STZ-induced apoptosis and increased β-cell neogenesis, indicating its effect on islets and β-cell mass. In conclusion, it was found that the antidiabetic effect of TSE on STZ-induced diabetes resulted from complex mechanisms of β-cell neogenesis, calcium handling, GLUT-2, GLUT-4, and SREBP-1c. These findings show the scope for formulating a new herbal drug for diabetes therapy.

Role of exogenous nitric oxide donor in treatment of decompensated hemorrhagic shock in normotensive and hypertensive rats

INTRODUCTION

In this study, we investigated the role of exogenous NO donor, sodium nitroprusside (SNP), on hemodynamic responses and survival rate during decompensated hemorrhagic shock in normotensive and hypertensive rat.

METHODS

Male wistar rats were divided into normotensive and hypertensive groups (n = 12 each). Then, the animals were subjected to decompensated hemorrhagic shock by withdrawing blood until the mean arterial pressure (MAP) reached to 40 mmHg. After the shock period, the animals were randomly assigned to SNP-treated (0.5 mg/kg) and control groups (n = 6 each). MAP and heart rate (HR) were monitored throughout the experiment and 60 min after the administration of drug. Serum NO concentrations were measured. The survival rate was counted during next 72 h.

RESULTS

Infusion of SNP caused no significant changes in MAP and HR in normotensive and hypertensive animals. Hemorrhagic shock increased serum NO concentration and SNP administration reduced serum NO concentration in either normotensive or hypertensive groups. Survival counts during 72 h after experiment did not improve by SNP administration, and there were no significant differences between normotensive and hypertensive groups.

CONCLUSION

SNP administration cannot improve hemodynamic responses and survival count during decompensated hemorrhagic shock in normotensive and hypertensive animals.

Hemodynamic responses and serum nitrite concentration during uncontrolled hemorrhagic shock in normotensive and hypertensive rats

BACKGROUND

We evaluated the effect of hypertension on hemodynamic responses and serum nitrite concentrations in normotensive (NT) and deoxycorticosteron acetate (DOCA)-Salt hypertensive (HT) rats.

METHODS

Uncontrolled hemorrhagic shock was induced in NT and HT rats (n=7 each) by preliminary bleed of 25 ml/kg followed by a 75% tail amputation. The mean arterial pressure (MAP), heart rate and serum nitrite were measured pre-hemorrhage and during hemorrhage.

RESULTS

Changes in time-averaged MAP after hemorrhage were significantly greater in HT group than NT. After resuscitation, the HT rats failed to restore MAP to baseline level. Serum nitrite level in both groups was significantly increased during shock period. Survival rate of HT animals was lower than NT group, although it was not statistically significant.

CONCLUSIONS

Marked reduction of MAP and less improvement after resuscitation suggested the less adaptation of cardiovascular system in HT animals which may interfere with management of these subjects during uncontrolled hemorrhagic shock.

Effect of chronic L-Arginine supplementation on aortic fatty streak formation and serum nitric oxide concentration in normal and high-cholesterol fed rabbits

Several reports indicated the beneficial effects of short-term L-Arginine (L-Arg) administration on atherosclerosis processes. The aim of this study was to evaluate the effect of chronic L-Arg supplementation on serum lipid profile, aortic Fatty Streak (FS) formation, and serum Nitric oxide (NO) concentration in Normal Diet (ND) and High-Cholesterol Diet (HCD) fed rabbits. 24 male rabbits were randomly divided into four groups (n=6 in each group) (i): ND for seven months; (ii): ND for 1 month plus ND + L-Arg for six months; (iii): HCD (1%) for 1 month plus HCD (0.5%) for six months; (iv): HCD (1%) for 1 month plus HCD (0.5%) + L-Arg for six months. At the end of the study, histological evaluation of aortic FS formation was performed. Blood samples were taken for serum lipid profile and NO concentrations. L-Arg did not change serum total cholesterol, triglyceride, LDL and LDL/HDL ratio in normal and hypercholesterolemic rabbits (p>0.05). Histological examination of thoracic aortae revealed that the HCD group had higher FS formation compared to the ND group (2.1 ± 0.16 vs. 0 ± 0; respectively; p<0.05) and L-Arg supplementation did not attenuate FS formation in the HCD group (1.93 ± 0.17 compare to 2.1 ± 0.16; p>0.05). Serum NO level in the HCD group was higher than ND groups (p<0.05). Chronic L-Arg supplementation did not alter serum NO concentration either in the hypercholesterolemic or in the ND group (p>0.05). It seems that chronic L-Arg supplementation does not have beneficial effects on aortic fatty streak formation, serum lipids and NO concentrations in this model of experimental hypercholesterolemia.

Different effects of L-arginine on morphine tolerance in sham and ovariectomized female mice

OBJECTIVE

The roles of gonadal hormones and nitric oxide (NO) on the analgesic effects of morphine, tolerance to morphine, and their interactions have been widely investigated. In the present study, the effect of L-arginine (an NO precursor) on morphine tolerance in sham and ovariectomized (OVX) female mice was investigated.

METHODS

Forty mice were divided into sham and OVX groups. On the first day, a hot plate test ((55±0.2) °C; cut-off 30 s) was carried out as a base record 15 min before injection of morphine (10 mg/kg, subcutaneously (s.c.)) and was repeated every 15 min after injection. The sham group was then divided into two subgroups: sham-tolerance-L-arginine (Sham-Tol-LA) and sham-tolerance-saline (Sham-Tol-Sal) which received either L-arginine 50 mg/kg (intraperitoneally (i.p.)) or saline 10 ml/kg (i.p.), respectively, three times in a day for three consecutive days. Morphine tolerance was induced in animals by injecting 30 mg/kg morphine (s.c.) three times/day for three days. This treatment was also used for OVX subgroups. On the fifth day, the hot plate test was repeated. The analgesic effect of morphine was calculated as the maximal percent effect (MPE). The results were compared using repeated measure analysis of variance (ANOVA).

RESULTS

There was no significant difference in MPE between the OVX and sham groups. The MPEs in both the Sham-Tol-Sal and OVX-Tol-Sal groups were lower than those in both the sham and OVX groups (P<0.01). The MPE in the OVX-Tol-Sal group was greater than that in the Sham-Tol-Sal group (P<0.01). The MPE in the Sham-Tol-LA group was higher than that in the Sham-Tol-Sal group (P<0.01). However, there was no significant difference between the Sham-Tol-LA and sham groups or between the OVX-Tol-LA and OVX-Tol-Sal groups.

CONCLUSIONS

The results of the present study showed that repeated administration of morphine causes tolerance to the analgesic effect of morphine. L-arginine could prevent tolerance to morphine but its effect was different in the presence of ovarian hormones.

Chronic treatment with the nitric oxide synthase inhibitor, L-NAME, attenuates estradiol-mediated improvement of learning and memory in ovariectomized rats

INTRODUCTION

The role of ovarian hormones and nitric oxide in learning and memory has been widely investigated.

OBJECTIVE

The present study was carried out to evaluate the effect of the nitric oxide synthase (NOS) inhibitor, N (G)-nitro-L-arginine methyl ester (L-NAME), on the ability of estradiol to improve learning in OVX rats using the Morris water maze.

METHODS

Forty rats were divided into five groups: (1) ovariectomized (OVX), (2) ovariectomized-estradiol (OVX-Est), (3) ovariectomized-L-NAME 10 (OVX-LN 10), (4) ovariectomized-L-NAME 50 (OVX-LN 50) and (5) ovariectomized-estradiol-L-NAME 50 (OVX-Est-LN 50). The animals in the OVX-Est group were treated with a weekly injection of estradiol valerate (2 mg/kg; i.m.). The OVX-LN 10 and OVX-LN 50 groups were treated with daily injections of 10 and 50 mg/kg L-NAME (i.p.), respectively. The animals in the OVX-Est-LN 50 group received a weekly injection of estradiol valerate and a daily injection of 50 mg/kg L-NAME. After 8 weeks, all animals were tested in the Morris water maze.

RESULTS

The animals in the OVX-Est group had a significantly lower latency in the maze than the OVX group (p<0.001). There was no significant difference in latency between the OVX-LN 10 and OVX-LN 50 groups in comparison with the OVX group. The latency in the OVX-Est-LN 50 group was significantly higher than that in the OVX-Est group (p<0.001).

CONCLUSION

These results show that L-NAME treatment attenuated estradiol-mediated enhancement of spatial learning and memory in OVX rats, but it had no significant effect in OVX rats without estrogen, suggesting an interaction of nitric oxide and estradiol in these specific brain functions.

Effects of diabetes on myocardial capillary density and serum angiogenesis biomarkers in male rats

INTRODUCTION

Cardiovascular disease is one of the main causes of mortality and morbidity in diabetic patients. This study evaluated the effects of diabetes on myocardial capillary density and several serum angiogenic factors including nitric oxide, vascular endothelial growth factor, and soluble vascular endothelial growth factor receptors.

METHODS

Twelve male rats were divided into two groups: control and diabetic (n = 6 each). Diabetes was induced with a single dose of streptozotocin (50 mg/kg). After 21 days, capillary density in the myocardial tissue was evaluated using immunohistochemical staining and is reported as capillaries per mm². Blood samples were collected before and after the induction of diabetes.

RESULTS

In the diabetic group, serum nitric oxide and soluble vascular endothelial growth factor receptor 2 concentrations were lower than the levels in the control group, while the level of soluble vascular endothelial growth factor receptor 1 was significantly higher. There was no significant change in the serum vascular endothelial growth factor concentration between the diabetic and control groups; however, the ratio of vascular endothelial growth factor to vascular endothelial growth factor receptor 1 was significantly lower in the diabetic animals. The myocardial capillary density was also lower in the diabetic group compared with the control group (1549 ± 161 vs. 2156 ± 202/mm², respectively).

CONCLUSION

Reduced serum nitric oxide and vascular endothelial growth factor receptor 2 levels, increased serum vascular endothelial growth factor receptor 1 levels and a lower vascular endothelial growth factor to vascular endothelial growth factor receptor 1 ratio may be responsible for the decreased myocardial capillary density in diabetic rats.

The effect of chronic administration of L-arginine on the learning and memory of estradiol-treated ovariectomized rats tested in the morris water maze

OBJECTIVE

The present study was carried out to evaluate the effect of L-arginine on the learning and memory of estradiol-treated ovariectomized (OVX) rats.

METHODS

Forty-eight rats were divided into six groups: (1) sham, (2) OVX, (3) sham-Est, (4) OVX-Est, (5) sham-Est-LA, and (6) OVX-Est-LA. The animals of the sham-Est and OVX-Est groups were treated by weekly injection of estradiol valerate (2mg/kg). The sham-Est-LA and OVX-Est-LA groups were treated in the same manner but with an additional daily injection of L-arginine (200mg/kg). After eight weeks, animals of all groups were tested in the Morris water maze. The escape latency and path traveled to reach the platform were compared between groups.

RESULTS

Time latency and path length in the OVX group were significantly higher than in the sham group (P<0.05). The OVX-Est group had a significantly shorter traveled path length and time latency compared to the OVX group (P<0.001). Time latency and path length in the sham-Est group was significantly higher than in the sham group (P<0.001). Time latency and path length in the OVX-Est-LA group were significantly higher than in the OVX-Est group.

CONCLUSIONS

These results allow us to propose that chronic treatment with estradiol enhances the spatial learning and memory of OVX rats, and that long term L-arginine treatment attenuates the effects of improvement produced by estradiol in OVX rats.

The effect of L-arginine and L-NAME on pentylenetetrazole induced seizures in ovariectomized rats, an in vivo study

The role of ovarian hormones and nitric oxide (NO) on seizure and their interaction have been widely investigated. The present study carried out to evaluate the effect of chronic administration of L-arginine (LA) and L-NAME (LN) on pentylenetetrazole (PTZ) induced epilepsy in ovariectomized (OVX) and naïve female rats. Fourty-eight female rats were randomly divided into six groups (n=8) as follows: (1) sham, (2) ovarectomized (OVX), (3) sham-LA, (4) sham-LN, (5) OVX-LA, and (6) OVX-LN. The animals of sham-LA and OVX-LA received daily injection of 500 mg/kg L-arginine (i.p.) during 4 weeks. Sham-LN and OVX-LN were treated by 10 mg/kg L-NAME (i.p.) daily for 4 weeks. The animals of sham and OVX groups received 1 ml/kg saline (i.p.) instead of L-arginine and L-NAME. The latencies to minimal clonic seizures (MCS) and generalized tonic-clonic seizures (GTCS) after intraperitoneal injection of penetylenetetrazole (PTZ, 90 mg/kg) was recorded and compared between groups. A significant increase in the GTCS, but not MCS, latency was seen in OVX rats in comparison with sham-operated animals. Pretreatment of animals with L-NAME resulted in a significant increase in the GTCS and MCS latencies in sham group while no significant effects were seen in OVX rats. On the contrary, while pretreatment with L-arginine had no effects on MCS and GTCS latencies in sham group, a significant decrease in GTCS latency was observed in OVX rats. It is concluded that ovarian sex hormones affect seizure thresholds induced by PTZ and NO has a role on seizures susceptibility following PTZ administration. This NO effect might be differing in the presence or absence of ovarian hormones, but further investigations need to be done.

Vascular endothelial function in health and diseases

The vascular endothelium constitutes approximately 1% of body mass (1kg) and has a surface area of approximately 5000m(2). The endothelium is a multifunctional endocrine organ strategically placed between the vessel wall and the circulating blood, and has a key role in vascular homeostasis. The endothelium is both a target for and mediator of cardiovascular disease. The endothelium releases several relaxing and constricting factors, which can affect vascular homeostasis. Endothelial dysfunction, whether caused by physical injury or cellular damage, leads to compensatory responses that alter the normal homeostatic properties of the endothelium. In this review, we summarized some physiological aspects of endothelial function and then we discussed endothelial dysfunction during some pathological conditions.

Baroreflex gain in normotensive and GH hypertensive rats before and after early gonadectomy

The authors have assessed arterial baroreflex gain in urethane-anesthetized normotensive and New Zealand genetically hypertensive (GH) rats and investigated the effect of gonadectomy in adult animals at 3 weeks of age postnatally. No gender differences in resting blood pressures existed for either normotensive or GH strains. In normotensive animals, bradycardic gain was greater than tachycardic gain and was lower in females than in males. Tachycardic gain was similar in GH and normotensive rats of either sex, but bradycardic gain was lower in GH. Gonadectomy had no effect on baroreflex gain in male or female animals of either strain.

The effect of hypertension on serum nitric oxide and vascular endothelial growth factor concentrations. A study in DOCA-Salt hypertensive ovariectomized rats

CardioVascular Disease (CVD) accounts for considerable mortality and morbidity in developed countries. Most of the common forms of CVD, such as hypertension, are caused by functional and structural changes in endothelial function. This study was designed to study the effect of hypertension on serum Nitric Oxide (NO) and Vascular Endothelial Growth Factor (VEGF) concentrations in DOCA-Salt hypertensive ovariectomized rats. Thirty female rats were ovariectomized. Blood samples were taken and the animals were divided into hypertensive and control groups. Hypertension was induced by DOCA-Salt method. DOCA was injected 30 mg/kg of body weight subcutaneously, twice a week with NaCl 1% instead of tap water for drinking throughout the experiment. The control group received normal saline injection with usual drinking water. Results showed that serum NO concentration in DOCA-Salt hypertensive rats was lower than the control group (18.35 +/- 5.31, 45.01 +/- 12.54 micromol/l, respectively) (p < 0.05). Also, the mean serum VEGF concentration was raised after induced hypertension (120.55 +/- 8.11 vs. 88.58 +/- 2.24 pg/ml) (p < 0.05). In conclusion, reduced serum NO and increased serum VEGF concentrations in hypertensive animals support the concept of endothelial dysfunction in hypertensive subjects.

Serum level of vascular endothelial growth factor is increased by estrogen replacement therapy in normotensive and DOCA–Salt hypertensive ovariectomized rats

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in developed countries. Previous studies have shown that hormone replacement therapy reduces the risk of CVD in postmenopausal women, however, the mechanism remains unclear. This study was designed to evaluate the effect of estrogen on serum vascular endothelial growth factor (VEGF) concentration in normotensive and hypertensive ovariectomized rats.

METHODS

Forty-eight female rats were ovariectomized and randomly divided into 6 groups. Hypertension was induced by DOCA-Salt method. DOCA was injected 30 mg/kg of body weight subcutaneously, twice a week with NaCl 1% instead of tap water for drinking throughout the experiment. Estradiol valerate (Es) was injected 2 mg/week i.m. The groups were as follows: (i) DOCA (4 weeks) and DOCA+Es (6 weeks); (ii) DOCA (10 weeks); (iii) Normal saline (N/S) (4 weeks) and Es (6 weeks); (iv) N/S 10 weeks; (v) DOCA (4 weeks), and (vi) N/S (4 weeks). Serum VEGF concentration was measured in groups 1 to 4.

RESULTS

Results showed that in normotensive animals that received estrogen treatment, serum VEGF concentration was significantly higher than those not receiving estrogen (269+/-41 vs. 106+/-36 pg/ml) (P<0.05). In hypertensive group, serum VEGF level was also increased after estrogen therapy compare to those not receiving estrogen (326+/-55 vs. 121+/-28 pg/ml (P<0.05).

CONCLUSION

It is possible that the increase in serum VEGF concentration after estrogen therapy may contribute to the cardiovascular effects of estrogen in normotensive and hypertensive conditions.