Marion Ehrich - US grants

The long term objective is to provide a means for reducing delayed neuropathy in man and animals exposed to certain organophosphates. As organophosphorus compounds are widely used today in agriculture and industry, risk is relatively high for accidental and occupational exposure. Although antidotes for acute toxicities are available, no specific treatment has been developed for the irreversible neuropathy that occurs weeks to months after exposure to some of these compounds. As recently demonstrated in our laboratory and others, adrenocorticoid hormones appear promising as agents to provide some moderation of the delayed neurotoxic effects of organophosphorus compounds. Using triorthotolyl phosphate (TOTP) to induce delayed neuropathy in chickens, we will examine a wide range of dietary concentrations of a natural corticoid, corticosterone, for effects on indices of this delayed neuropathy, such as clinical signs, histopathology, electrophysiology and neurotoxic esterase activity. We will observe effects of the corticosterone per se on the health of the birds by monitoring the heterophil/lymphocyte ratio, liver function, and feed efficiency. Also, as part of the work proposed, some properties of corticoids that may be relevant in moderation of organophosphate induced delayed neuropathy will be examined. These will include type of corticoid, by using a mineralocorticoid (deoxycorticosterone), a glucocorticoid (triamcinolone), and corticosterone, which has both properties, to modify TOTP-induced delayed neuropathy. The possibility that corticoids may alter metabolism of organophosphates, thereby providing protection, will be examined by comparing delayed neuropathy induced by a protoxicant (TOTP) with that induced by its active metabolite (phenyl saligenin phosphate) in the presence of corticosterone. The possibility that endogenous steroid may be substituting for exogenous steroid, as organophosphates inhibit steroidgenesis, will be examined by attempting to use ACTH rather than corticosterone to protect the birds from TOTP-induced delayed neuropathy. These studies should enhance our understanding of the basic pathogenetic mechanisms in organophosphate-induced delayed neurotoxicity, and, hopefully, lead to rational therapy.

biomedical equipment resource;

FULLERENES COUNTERACTING ORGANOPHOSPHORUS THREATS. Nerve agents used as agents of terror include organophosphorus (OP) compounds, neurotoxic substances that inhibit acetylcholinesterase (AChE) activity. When the neurotransmitter acetylcholine is not destroyed cholinergic poisoning can result. Contemporary treatment relies on blocking cholinergic receptors, removing OP compounds from AChE, and treating symptoms. This is often incomplete in poisoning with the potent and rapidly acting OP nerve agents, so additional countermeasures are desired. Our preliminary data show water soluble hydroxylated C60 fullerenes (C60-OH) have ability to decrease AChE inhibition in neuronal cells. Our preliminary data show no overt toxicity in mice after IV injection of a soluble C80-OH metallofullerene Trimetasphere[unreadable]. These data suggest in vivo potential of soluble fullerenes to safely detoxify OP toxicants. C60/C80-OH fullerenes and other soluble derivatives also have antioxidant properties likely to be useful against the oxidative stress associated with excitotoxicity resulting from rapid and life-threatening AChE depletion, effects that can be long-lasting and/or delayed and, when unopposed, contribute to neuropathy. Therefore, based on our preliminary data, the hypothesis is that soluble C60/C80-OH and other derivatives can decrease capability of OP compounds to inhibit AChE and also counteract oxidative effects. We predict that soluble C60/C80 derivatives can be safely administered as OP antidotes, either alone or in combination with currently accepted treatments (IV atropine, pralidoxime, diazepam). We propose to examine the ability of soluble C60/C80 derivatives to interact with OP nerve agent surrogates (DFP, paraoxon). Initial screening will be done in vitro by evaluating non-cytotoxic soluble C60/C80 derivatives for their ability to decrease OP-induced effects, including AChE inhibition, in neural tissue and neuronal cells. Using the best-performing compounds from the in vitro studies, experiments using mice will validate in vitro findings, examining the effectiveness of soluble C60/C80 derivatives as ameliorators of OP-induced effects on behavior, AChE inhibition, and brain neurochemistry and structure when given alone or in combination with traditional treatments. Successful identification of safe and effective fullerenes which have both AChE-protection and antioxidant properties will provide potential to protect and treat acute and delayed effects of nerve agent poisoning.