Galanin in the normal human pituitary and brain and in pituitary adenomas

Galanin-like immunoreactivity (IR) was measured by radioimmunoassay in extracts of non-tumorous and tumorous human pituitaries and in multiple sites in the human brain. Galanin-IR was present in considerable quantities in the non-tumorous pituitaries (21.4 +/- 1.2 pmol/g wet weight; mean +/- S.E.M., n = 30). In 25 pituitary tumours, galanin-IR was detectable in extracts of only nine, with a mean concentration of 11.5 +/- 4.4 pmol/g. Galanin-IR was undetectable in the remaining 16. Of ten brain sites, galanin-IR was detected only in the hypothalamus, where the concentration was 9.1 +/- 1.8 pmol/g (n = 5). On fast protein liquid chromatography of the non-tumorous pituitary extracts, galanin-IR mostly eluted in a peak with a retention time similar to that of synthetic porcine galanin. On gel permeation chromatography, galanin-IR eluted as a peak with an elution coefficient (Kav) of 0.72, also similar to that of porcine galanin, with additional preceding (Kav 0.62) and following (Kav 0.77) peaks of galanin-IR. These results show that healthy human pituitary and hypothalamus contain substantial amounts of galanin, whereas it is present in variable amounts or not at all in pituitary tumours. Chromatographic analysis suggests that pituitary galanin is present in three molecular forms, with the majority corresponding to synthetic porcine galanin.