Up-regulation of cholecystokinin receptors in the nucleus accumbens of the young prehypertensive spontaneously hypertensive rat.

We employed receptor autoradiography to test the hypothesis that changes in cholecystokinin neurotransmission in the striatum of the young spontaneously hypertensive rat (SHR) is involved in the development of hypertension. The binding density of 125I-Bolton Hunter labelled cholecystokinin octapeptide (125I-BH-CCK8) in the striatum of 5-week-old prehypertensive SHRs and its normotensive control the Wistar-Kyoto rat (WKY) was determined using computer-assisted densitometry. We found a significant increase in 125I-BH-CCK8 binding density in the nucleus accumbens of the SHR. No difference between the binding density of 125I-BH-CCK8 was found in the caudate-putamen and the prefrontal cortex of SHRs and WKYs. These results suggest that changes in CCK8S neurotransmission or receptor function are not secondary to an increase in arterial blood pressure and, therefore, may be involved in the development of hypertension.