Calcitonin ameliorates enhanced arterial contractility after chronic constriction injury of the sciatic nerve in rats

In addition to its regulatory effect on bone mass, calcitonin has been shown to relieve pain and alleviate peripheral circulatory disturbance in patients with Raynaud's syndrome and complex regional pain syndrome. In the present study, we investigated whether calcitonin ameliorates diminished blood flow and enhanced arterial contraction in response to noradrenaline in chronic constriction injury (CCI) of the sciatic nerve in rats. Following surgically induced CCI, laser Doppler flowmetry studies showed a significant decrease in plantar skin blood flow of the ipsilateral hind paw compared to the contralateral side. A subcutaneous bolus injection of elcatonin (20 U/kg), a synthetic derivative of eel calcitonin, significantly improved decreased skin blood flow in the ipsilateral side. In vitro analysis of plantar arteries isolated from the ipsilateral hind paw 7-13 days after the CCI procedure showed higher sensitivity to noradrenaline than the plantar arteries from the contralateral side. Elcatonin (0.1-10 nm) significantly reduced noradrenaline-induced contraction in the arteries of the ipsilateral side, whereas it had little effect on those of the contralateral side. These results suggest that calcitonin selectively ameliorates enhanced arterial contractility in CCI neuropathic rats, thus leading to its alleviating effect on peripheral circulatory disturbance.