Heterogeneity of plasma calcitonin gene-related peptide: partial characterisation of immunoreactive forms.

Calcitonin gene-related peptide (CGRP) in plasma is heterogeneous and derived from both neural tissues and from the thyroid gland in the rat. CGRP is widely distributed in neural and cardiovascular tissues, and also in the thyroid gland in rat. We have previously shown that the main source of circulatory CGRP is the perivascular nerves. The present study shows that, in addition to the neural tissues, the thyroid gland may also contribute to the circulating pool of immunoreactive-CGRP.