Expression of the neural cell adhesion molecule NCAM in endocrine cells

We examined the expression of the neural cell adhesion molecule
NCAM in a number of endocrine tissues of adult rat and in an
endocrine tumor cell line. NCAM was found by immunoelectron
microscopy to be present on the surface of all endocrine cells in
the three lobes of the hypophysis, although staining was relatively
less intense in the intermediate lobe, and in pancreatic islets.
Pituicytes, hypophyseal glial cells, were also labeled for NCAM. A
rat insulinoma cell line (RIN A2) also expressed NCAM as judged by
immunocytochemistry. Analysis of NCAM antigenic determinants (Mr
180, 140, and 120 KD) revealed large variations in the relative
proportions of NCAM polypeptides present in the different tissues.
Although all tissues and cell lines expressed NCAM-140, NCAM-180
was not detected in the adenohypophysis, pancreas, or adrenal
medulla, and NCAM-120 was found in none of the endocrine tissues or
cell lines except at low levels in the neurohypophysis. The tumor
cell line expressed significant levels of NCAM-180, which was most
abundant in the neurohypophysis. These results show that NCAM
expression appears to be a general property of endocrine cells,
although the antigenic composition differs markedly from that in
brain tissue. These data are discussed with regard to the
embryological origins of the different endocrine tissues, and
possible functional implications are suggested.