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

Pteridophyte

A new experimental model to study preneoplastic lesions in achalasia of the esophagus

PURPOSE: Develop an experimental model to study esophageal preneoplastic lesions induced by diethylnitrosamine in rats with achalasia. METHODS: Male Wistar rats were divided into four groups: control - C (n=8); rats with megaesophagus - B (n=8); rats treated with DEN - D (n=15) and rats with megaesophagus plus DEN - BD (n=15). Megaesophagus can be experimentally obtained in rats by topical application of benzalkonium choride. The morphology and PCNA labeling index of the epithelium were evaluated. RESULTS: The morphometric analysis showed an increase in epithelial thickness in the animals of group BD (2166?1012mm²) when compared to the other groups (C = 878?278mm²; B = 1746?144mm² and D = 1691?697mm²), mainly due to basal layer hyperplasia, besides an increase in the keratin of the superficial layer. The PCNA labeling index in the basal layer was significantly higher in the group BD (0,695?0,111) when compared to the other groups (C = 0,490?0,132; B = 0,512?0,215 and D = 0,477?0,198). CONCLUSIONS: Our data confirm in an experimental model the previous observation in humans of increased epithelial cell proliferation during the esophageal carcinogenic process in achalasia and may be useful to further studies on the mechanisms of the esophageal carcinogenesis and the the design of follow-up endoscopic studies for patients with achalasia

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 borning. 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

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 borning. 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