Influence of age and sex on high-fat diet-induced increase in blood pressure.

We are studying to elucidate the reason for increase in age-related hypertension and the mechanism thereof using rats. We would like to introduce model animals and the results obtained from these animal experiments. Based on a study regarding whether the elevation of blood pressure caused by dietary fat is due to excessive calorie intake and resulting body-weight gain or else fat itself--if so which type of fat is responsible for elevating blood pressure, it was suggested that elevated blood pressure was due to some effects specific to animal fat. According to a study if insulin resistance involves elevated blood pressure, it became apparent that the build-up of visceral fat caused by high-fat diet together with worsening of insulin sensitivity were responsible for elevating blood pressure. Next, we studied if there are sexual differences in dietary-fat induced hypertension and influence of male hormone. It became clear that the mechanism of elevated blood pressure caused by high-fat diet involved a condition of insulin resistance due to high-fat diet and furthermore, only when testosterone was present, the blood pressure was elevated. In addition, we studied aging effects on hypertension due to dietary fat. As a result, it became clear that the older the person gets, more likely he/she suffers from visceral obesity and conditions of insulin resistance, making blood pressure proneto rise. In summary, even without having excessively high calorie diet and without body weight gain, intake of excessive animal fat will cause visceral obesity and so do hypertension. Also, when taking high-fat diet, males tend to suffer from hypertension more often than females, suggesting testosterone is involved as the cause. Further, it was shown that the older the persons are, the greater the dietary effects result in, causing their blood pressures likely to increase.