Background: Catestatin, a chromogranin A-derived peptide, is a potent antagonist of nicotine-evoked catecholamine release. We know that catecholamine plays an important role in cardiovascular remodeling induced by hypertension, therefore we hypothesized that catestatin would affect target-organ structure during hypertension.
Methods: Twelve spontaneously hypertensive rats (SHRs) were randomized to SHR control group and catestatin group, the normal control group was comprised of six healthy Wistar-Kyoto rats of the same age. Tail-cuff blood pressure and pulse rate were obtained at weeks 1, 4 and 8. At the end of the eight-week period, the heart, abdominal aorta and left kidney were excised and weighed, VG staining was done and the intima-media thickness of vessels and the collagen volume fraction were assessed by an image acquisition and analysis system. The proliferating cell nuclear antigen (PCNA) was observed by immunohistochemistry, and real time reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA levels of proliferative genes including cyclin A, ki67 and PCNA in the abdominal aorta.
Results: All the parameters in SHR observed in the present study increased significantly compared to Wistar Kyoto rats (P < 0.01). With intervention with catestatin, the systolic blood pressure decreased slightly but it was not significantly different from the SHR control, the cardiac mass index and left ventricular mass index both decreased significant ly, the collagen volume fraction decreased by nearly 30% in the heart, by 25% in vessels and by 10% in the kidney, and the intima-media thickness and expression of proliferative genes, including cyclin A, ki67 and PCNA, in the abdominal aorta also decreased significant ly.
Conclusions: The present study indicated that catestatin could ameliorate proliferating changes of heart, kidney and vessels during hypertension, especially to the deposition of interstitial collagen. Blood pressure was not the main factor to mediate this effect, which suggested that catestatin could become a novel protective factor for hypertensive target organs.