Histological damage induced after ingestion of benzo-a-pyrene and 3-methylcholanthrene by the locust Gomphocerus sibiricus.

Using UV light in order to study accumulation of BaP or 3MC by Gomphocerus sibiricus, a locust strictly located between 2 000 and 2 800 m, we have pre viously shown that these HAP can be rapidly absorbed by midgut, then, accum ulated in many organs and essentially eliminated by Malpighian tubules (J.B ., 1999), presumably after partial degradation. Now we describe the effects of these carcinogenic polycyclic hydrocarbons at histological and cytologi cal levels. Wholly invaded, midgut epithelium is profoundly intoxicated, nu merous cells showing structural abnormalities or beeing destroyed: excessiv e merocrine secretion becoming finally holocrine. Connective and muscular t issues do not constitute effective barriers against toxic effects of the HA P. Fat body and muscles, though strongly impregnated with each of them, sho w only discrete cellular damage. Locally, the reproductive system is more c learly affected. Otherwise, nervous cord ganglia contain some dead cells, a nd we describe an effective swelling of the intercellular spaces. This poin t seems to imply disturbancies of the glial sheats which isolate neurons fr om their neighbours. Finally digestive caeca, strongly affected by HAP, are partly destroyed, especially after treatment by BaP. We suggest caeca coul d be a secondary route of degradation and excretion of HAP. Tubes of Malpig hi seem to be the principal route of their elimination; their epithelium is frequently severely injured and may sometimes disappear. As with mammals, we have to underline here similar differential cell susceptibilities within each organ of a locust. However what may be, we have perceived effective d isturbancies which are strong enough to involve a knock-down and finally de ath of a part of the treated locusts. This work gives us new opportunities for ulterior research, for example, with locusts sampled in a variety of bi otopes, strongly polluted or "not". Our UV test may be used as a first appr oach. (C) 2000 Editions scientifiques et medicales Elsevier SAS.