Histopathological study on the effect of octreotide.

The present investigation was performed to clarify the mechanism of action of octreotide. On a quantitative study by electron microscopy showed that lysosomes were markedly increased in the patients receiving octreotide. Growth hormone (GH) was shown to be in the secretory granules by the postembedding immunogold technique, but no GH immunostaining was noted of the lysosomes. The present investigation suggests that retention of secretory granules and subsequent lysosomal increase are the mechanism of GH-lowering effect of octreotide.