Pituitary growth hormone and somatotrophs in rats bearing chemically induced hepatomas

Measurement of pituitary growth hormone (GH) content by polyacrylamide gel electrophoresis (PAGE) showed that rats bearing diethylnitrosamine (DENA) induced hepatomas contained significantly less GH than age-related controls. Light microscopy of these pituitaries revealed many apparently dying somatotrophs in tumour bearing rats. By electron microscopy the somatotrophs of DENA hepatoma rats were relatively inactive and some clearly dying, which could account for the reduced hormone content. However, electron microscopy of somatotrophs of rats with 2-acetyl-aminofluorene (2-AAF) hepatic tumour nodules revealed many very active cells with greatly increased content of free ribosomes and many granules poised for imminent release. Other somatotrophs of these rats showed lysosomal activity indicating reduced secretion after an active phase.