The effect of hypophysectomy on the gastrointestinal tract was
studied in the rat 8 wk after operation,
particularly regarding the frequency and distribution of serotonin,
somatostatin and gastrin-immunoreactive
cells. Body weight, the length of the intestine and the thickness of the
mucosa of the antrum and small
intestine were all reduced in the hypophysectomised rats compared with
sham-operated and untreated
controls. In the hypophysectomised animals the serotonin-immunoreactive
cells were fewer in the antrum
and caecum, whereas they were more numerous in the proximal large intestine.
There
were fewer gastrin-immunoreactive cells in the antrum, while the
somatostatin-immunoreactive cells were more numerous in the
antrum and caecum. The significant influence of hypophysectomy on the
gastrointestinal tract could be
direct, but could also be associated with the marked effect of pituitary
deficiency on endocrine cells, known
to exert both trophic and antitrophic actions. However, it could also be
an
indirect effect on metabolism,
resulting in lower food intake, other endocrine cell systems, and growth
factors.