Historic perspectives and recent advances in major animal models of hypertension.

Hypertension and related cardiovascular diseases are the leading causes of death in many countries. The etiology of human essential hypertension is largely unknown. It is highly likely that hypertension is a complex and multifactorial disease resulting from the interaction of multiple genetic and environmental factors. Animal models of hypertension have been proved to be useful to study the pathogenesis of, and to find a new therapy for, hypertension. The aim of this article is to briefly review the most widely used rodent models of experimental hypertension, including history and recent advances. These models are classified as genetically-induced, environmentally-induced, pharmacologically-induced, and renal-induced hypertension according to the way of induction; the typical representatives of each of these major types of experimental hypertension are spontaneous hypertension, cold-induced hypertension, DOCA-salt-induced hypertension, and renal-induced hypertension, respectively. The processes of induction of hypertension, possible pathogenesis, characteristics, advantages, and limitations of these animal models are reviewed. In addition, the clinical implications of the above experimental models of hypertension are addressed.

Effect of resveratrol and in combination with 5-FU on murine liver cancer.

AIM: To study the anti-tumor effect of resveratrol and in combination with 5-FU on murine liver cancer. METHODS: Transplantable murine hepatoma22 model was used to evaluate the anti-tumor activity of resveratrol (RES) alone or in combination with 5-FU in vivo. H22 cell cycles were analyzed with flow cytometry. RESULTS: Resveratrol could inhibit the growth of murine hepatoma22, after the mice bearing H22 tumor were treated with 10 mg/kg or 15 mg/kg resveratrol for ten days, and the inhibition rates were 36.3% (n = 10) and 49.3% (n = 9), respectively, which increased obviously compared with that in control group (85+/-22 vs 68+/-17, P<0.01). RES could induce the S phase arrest of H22 cells, and increase the percentage of cells in S phase from 59.1% (n = 9) to 73.5% (n = 9) in a dose-dependent manner (P<0.05). The enhanced inhibition of tumor growth by 5-FU was also observed in hepatoma22 bearing mice when 5-FU was administered in combination with 10 mg/kg resveratrol. The inhibition rates for 20 mg/kg or 10 mg/kg 5-FU in combination with 10 mg/kg resveratrol were 77.4% and 72.4%, respectively, compared with the group of 20 mg/kg or 10 mg/kg 5-FU alone, in which the inhibition rates were 53.4% and 43.8%, respectively (n = 8). There was a statistical significance between the combination group and 5-FU group. CONCLUSION: RES could induce the S phase arrest of H22 cells and enhance the anti-tumor effect of 5-FU on murine hepatoma22 and antagonize its toxicity markedly. These results suggest that resveratrol, as a biochemical modulator to enhance the therapeutic effects of 5-FU, may be potentially useful in cancer chemotherapy.

Effect of resveratrol on cell cycle proteins in murine transplantable liver cancer.

AIM: To study the antitumour activity of resveratrol and its effect on the expression of cell cycle proteins including cyclin D1, cyclin B1 and p34cdc2 in transplanted liver cancer of murine. METHODS: Murine transplanted hepatoma H22 model was used to evaluate the in vivo antitumor activity of resveratrol. Following abdominal administration of resveratrol, the change in tumour size was recorded and the protein expression of cyclin D1, cyclin B1 and p34cdc2 in the tumor and adjacent noncancerous liver tissues were measured by immunohistochemistry. RESULTS: Following treatment of H22 tumour bearing mice with resveratrol at 10 or 15 mg/kg bodyweight for 10 days, the growth of murine transplantable liver cancer was inhibited by 36.3% or 49.3%, respectively. The inhibitory effect was significant compared to that in control group (P<0.05). The level of expression of cyclin B1 and p34cdc2 protein was decreased in the transplantable murine hepatoma 22 treated with resveratrol whereas the expression of cyclin D1 protein did not change. CONCLUSION: Resveratrol exhibits anti-tumour activities on murine hepatoma H22. The underlying anti-tumour mechanism of resveratrol might involve the inhibition of the cell cycle progression by decreasing the expression of cyclinB1 and p34cdc2 protein.

Expression of angiotensin II type 1 (AT(1)) receptor in the rostral ventrolateral medulla in rats.

In the present study, the changes of amino acids release in the spinal cord after the application of angiotensin II (ANG II) in the rostral ventrolateral medulla (RVLM) and the distribution of ANG receptors on neurons of the RVLM were investigated. A microdialysis experiment showed that microinjection of angiotensin II into the RVLM significantly (P < 0.01) increased the release of aspartate and glutamate in the intermediolateral column of the spinal cord. Immunofluorescence technique combined with confocal microscopy demonstrated that most of the glutamatergic and GABAergic neurons in the RVLM of both Wistar and spontaneously hypertensive rats (SHR) were double labeled with ANG type 1 (AT1) receptor. Immunocytochemical studies demonstrated that the mean optic density of AT1 receptor of the cell surface as well as the whole cell was higher (P < 0.05) in SHR than that in Wistar rats, indicating that the higher expression of AT1 receptors in the RVLM may contribute to the higher responsiveness of SHR to ANG II stimulation. Immunogold staining and electronmicroscopic study demonstrated that AT1 receptor in the RVLM was distributed on the rough endoplasmic reticulum, cell membrane, and nerve processes. The results suggest that effects evoked by ANG II in the RVLM are closely related to glutamatergic and GABAergic pathways. These results indirectly support the hypothesis that ANG II in the RVLM may activate vasomotor sympathetic glutamatergic neurons, leading to an increase in sympathetic nerve activity and arterial blood pressure.

Anti-hepatoma activity of resveratrol in vitro.

AIM: To study the anti-tumor effect of resveratrol alone and the synergistic effects of resveratrol with 5-FU on the growth of H22 cells line in vitro. METHODS: The number of cells was measured by MTT method the morphological changes of H22 cells were investigated under microscopy and electron microscopy examination. RESULTS: Resveratrol inhibited the growth of hepatoma cells line H22 in a dose- and time-dependent manner, IC50 of the resveratrol on H22 cells was 6.57mg x L(-1),The synergistic anti-tumor effects of resveratrol with 5-FU increased to a greater extent than for H22 cells treated with 5-FU alone (70.2% vs 28.4%) P<0.05 .Under microscope and electron microscope, characteristics of apoptosis such as typical apoptotic bodies were commonly found in tumor cells in the drug-treated groups. CONCLUSION: Resveratrol can suppresses the growth of H22 cells in vitro,its anti-tumor activity may occur through the induction of apoptosis.