Résumé

P564

Morphological study of adrenal glands in Wistar rat subjected to chronic dehydration: comparison with a desert rodent Gerbillus tarabuli

Mlle S. AOUICHAT^a, Mme A. DEKAR-MADOUI^a, Mlle H. TOUATI^a, Mme S. OUALI-HASSENAOUI^a

^a Université des Sciences et de la Technologie Houari Boumediene, Faculté des Sciences Biologiques, Alger

Diet constitutes an important source of water in desert environments. For rodents surviving under such drastic conditions suggests a state of permanent stress. So, we investigated the effect of chronic dehydration on plasma parameters and adrenal gland structure compared to that of Gerbillus tarabuli.

12 male rats were divided into control and dehydrated group submitted to ingestion of 2% saline solution for 7 days. Gerbils (n=6) group was fed with barely grain. Osmolality, and hematocrit were determined and adrenal glands were treated by histological technique.

Dehydrated rats show a significant increase in hematocrit and osmolality; confirming hypovolemic state. Gerbil presented low hematocrit suggesting that their blood contains more water. However, its osmolality was similar to that of dehydrated rats. Dehydration induced degranulation of adrenaline chromaffine cells and enlargement of capillaries, suggesting strong adrenalin release. However, gerbils showed the same structure as that of controls, indicating basal stress hormone release. Parallely, the zona fasciculata (ZF) of dehydrated rats and gerbils, show a loss of the spongy appearance and capillary dilatations which can be related to an increased production of glucocorticoides. Considering all results, it appears that the chronic dehydration constitutes a stress condition in Wistar rats, but shortage of water, which characterizes the arid environment of gerbil is not a stress factor for this specie. In gerbil, morphological features of ZF, don’t seem to be a stress response; it would be rather an indication of metabolic strategy, probably for metabolic water production.

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