Hypertension and diabetes mellitus are strongly associated conditions from epidemiologic, genetic, and pathophysiologic points of view. It is well known that hypertension and diabetes mellitus often coexist in humans. One of the most frequent and important complications of IDDM (Insulin-Dependent Diabetes Mellitus) is hypertension. Thus Hypertension is frequently seen in insulin-dependent diabetes mellitus (TDDM), but the mechanism of the hypertension is unknown. An animal model of IDDM-hypertension could be helpful in determining the mechanism, but experimental IDDM has been infrequently and irregularly associated with hypertension. In an attempt to develope a consistent model of IDDM-hypertension, we would made hybrid strain of BBDP/Wor rat, as IDDM model animal, and SHR, as essential hypertension model animal, by cross-mating.
In hybrid groups, body weight gains were higher than Wistar, SHR, and BBDP rats. Systolic blood pressures were middle level between Wistar and SHR, and that of F2 exhibited a tendency to increase than F1. Plasma glucose and insulin levels were not significantly different among the experimental groups but insulin level of F2 was near to that of SHR. Densities of nerve fiber with immunoreactivity to Neuropeptide Y (NPY) in paraventricular nucleus and arcuate nucleus of SHR and BBDP rats significantly higher than Wistar rat. Also, density of NPY in paraventricular and arcuate nucleus of BSF2 and SBF2 rats significantly higher than Wistar rat. And these morphological appearances in both hybrids similir to SHR and BBDP rats. On the other hand, 3 heads of total 26 BSF2 rats developed IDDM; general characteristics of DM essentially same to BBDP rats, but initial time of DM delayed and process of DM toward death fast compared with BBDP rat. In both hybrids, DM was developed as soon as blood pressure decreased.
In conclusion, cross mated hybrids with SHR and BBDP rat inherited hypertension and DM phenotype as recessive pattern, and developing order of both phenotype is hypertension was prefered to DM. Therefore, these hybrids may will be expected as successive model of hypertension and DM.
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