A study of the effects of pinealectomy on intestinal cell proliferation in infant newborn rats.

Purpose: Study the proliferation rate of jejunum and large intestine crypt epithelial cells, in rats pinealectomized immediately after birth.

Methods: Twenty-four male Wistar rats were distributed into two groups: Acute group (n=12) and Chronic group (n=12). Six animals of each group were operated for removal of the pineal gland (pinealectomy-PnX), and other six were controls (sham pinealectomy-C). Animals from acute and chronic group were sacrificed 15 and 90 days after the surgery, respectively.

Results: In acute group, pinealectomy of new-born rats has not caused significant alteration in cell proliferation (PnX=58.77+/-1.77 and C=60.88+/-1.10 in the descending colon/PnX=31.56+/-0.45 and C=31.73+/-0.47 in the proximal jejunum) and in crypt cell population (PnX=24.92+/-4.82 and C=23.60+/-2.48 in the descending colon/PnX=39.92+/-3.49 and C=44.32+/-5.56 in the proximal jejunum). However, in chronic group there was an uprising crypt cell production per crypt in the proximal jejunum (PnX=57.54+/-2.19 and C=47.19+/-7.3)and in the descending colon (PnX=37.78+/-2.22 and C=17.92+/-2.28).

Conclusion: As the increase of intestinal crypts epithelial cells in chronic group is a carcinogenesis predetermining factor, the understanding of the interaction between pineal gland and this event has great importance.