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.
OBJECTIVE
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.


CONCLUSIONS
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.
da Silva
Júlio César Fernandes
JC
Department of Pathology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil.
Vespúcio
Marcelo Vinícius Oliveira
MV
Dalio
Renato Belini
RB
Guimarães
Marco Aurelio
MA
Pinto
André Péra Marques
AP
Garcia
Waynice Neiva de Paula
WN
Zucoloto
Sergio
S
Garcia
Sérgio Britto
SB
D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D003106:Colon / Q000473:pathology*; D006965:Hyperplasia; D008297:Male; D009490:Neurosecretory Systems / Q000473:pathology* / Q000502:physiology*; D016612:Paraffin Embedding; D010870:Pineal Gland / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar