Salmon calcitonin in lizard brain: a possible neuroendocrine transmitter.

Calcitonin is a polypeptide which until recently was thought to be concerned primarily with the control of body calcium. Recent studies carried out with radioimmunoassay have demonstrated the presence of this peptide in brain and we have carried out an immunohistochemical study showing the presence of high concentrations of calcitonin in the nerve varicosities and terminals of the hypothalamus and in particular the median eminence of the lizard Lacertus muralis. The distribution of this calcitonin, which cross-reacted with anti-salmon calcitonin, suggests that this polypeptide and/or its flanking peptides may function as a neuroendocrine neurotransmitter.