Publications by authors named "André Pera Marques Pinto"

2 Publications

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

Acta Cir Bras 2006 Jan-Feb;21(1):16-20. Epub 2006 Feb 13.

University Hospital, FMRP, USP, São Paulo, Brazil.

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.
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August 2006

Hyperplasia of the colonic neuroendocrine cells after pinealectomy in rats. The new evidence for the existence of connections between the distant parts of the diffuse neuroendocrine system.

Neuro Endocrinol Lett 2005 Oct;26(5):511-4

Department of Pathology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil.

Objectives: The diffuse neuroendocrine system (DNES) participates in the systemic homeostasis and may work as a unified system with integrated functions but anatomically disperse. However, the mechanisms that are involved in the integration of the distant parts of the DNES are poorly known. This study is aimed on the effects of a pinealectomy on the population of the neuroendocrine cells (NECs) in the colon of rats.

Methods: A group of seven newborn rats and one of adult rats were submitted to a pinealectomy. The animals were sacrificed after 15 days and 90 days, respectively. The control groups of adult and newborn rats were subjected to a 'sham surgery' and then sacrificed after similar periods of time. Paraffin-included sections of the colon samples were stained by the Churukian-Schenk method in order to selectively stain the NECs. The NEC index was estimated by the expression: iNEC = NECs population per crypt/Total cell population of the crypt. The results were expressed as median and absolute range, and the statistical significance was demonstrated by the Mann-Whitney (U) test.

Results: The morphometric analysis showed a significant increase in the number of colonic NECs of the adult rats subjected to a pinealectomy when compared to the controls. No statistical difference was observed between the iNECs of the newborn groups of rats.

Conclusion: This finding suggests the existence of regulatory mechanisms that integrate distant parts of the DNES, by adapting the population of the endocrine cells after the ablation of an important component of the system. Further studies on the mechanisms involved in the integration of the DNES may be facilitated by the simple experimental model that we propose.
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October 2005