An animal model to study health effects during continuous low-dose exposure to the nerve agent VX

Distinguishing between endocrine disruption and non-specific effects on endocrine systems

The endocrine system is responsible for growth, development, maintaining homeostasis and for the control of many physiological processes. Due to the integral nature of its signaling pathways, it can be difficult to distinguish endocrine-mediated adverse effects from transient fluctuations, adaptive/compensatory responses, or adverse effects on the endocrine system that are caused by mechanisms outside the endocrine system. This is particularly true in toxicological studies that require generation of effects through the use of Maximum Tolerated Doses (or Concentrations). Endocrine-mediated adverse effects are those that occur as a consequence of the interaction of a chemical with a specific molecular component of the endocrine system, for example, a hormone receptor. Non-endocrine-mediated adverse effects on the endocrine system are those that occur by other mechanisms. For example, systemic toxicity, which perturbs homeostasis and affects the general well-being of an organism, can affect endocrine signaling. Some organs/tissues can be affected by both endocrine and non-endocrine signals, which must be distinguished. This paper examines in vitro and in vivo endocrine endpoints that can be altered by non-endocrine processes. It recommends an evaluation of these issues in the assessment of effects for the determination of endocrine disrupting properties of chemicals. This underscores the importance of using a formal weight of evidence (WoE) process to evaluate potential endocrine activity.

Effect of five acetylcholinesterase reactivators on tabun-intoxicated rats: induction of oxidative stress versus reactivation efficacy

Oxime reactivators HI-6, obidoxime, trimedoxime, K347 and K628 were investigated as drugs designed for treatment of tabun intoxication. The experiments were performed on rats in order to simulate real conditions. Rats were intoxicated with one LD(50 )of tabun and treated with atropine and mentioned reactivators. Activities of erythrocyte acetylcholinesterase (AChE), plasma butyrylcholinesterase (BChE) and brain AChE were measured as markers of reactivation efficacy. An estimation of low molecular weight antioxidant levels using cyclic voltammetry was the second examination parameter. The evaluation of cholinesterases activity showed good reactivation potency of blood AChE and plasma BChE by commercially available obidoxime and newly synthesized K347. The potency of oximes to reactivate brain AChE was lower due to the poor blood-brain barrier penetration of used compounds. Commercially available reactivator HI-6 and newly synthesized K628 caused oxidative stress measured by cyclic voltammetry as antioxidant level. The oxidative stress provoked by HI-6 and K628 was found to be significant on probability level P = 0.05. The others reactivators did not affect antioxidant levels.