Full Project – EFFECT OF AQUEOUS EXTRACT OF COWPEA (Vigna unguiculata) ON VISUOSPATIAL LEARNING AND MEMORY IN ACUTE LEAD-INDUCED NEUROTOXICITY IN MICE

Lead is a poisonous metal, which exist in both organic (Tetraethyl lead) and inorganic (lead acetate and lead chloride) forms in the environment (Shalan et al., 2005). The main sources are medicines, paintings, pipes, ammunition. And more recently, it is found in alloys for welding storage materials for chemical reagents (Garazaet al., 2006). Exposure to lead mostly occurs through the respiratory and gastrointestinal systems. Lead is conjugated by the liver and passed to the kidney, where it is excreted out in urine and the rest accumulates in various body organs. This affects many biological activities at the molecular, cellular and intercellular levels, which may result in morphological alterations that can remain even after lead level has fallen (Flora et al., 2006; Ibrahimet al., 2012).

Lead poisoning or lead intoxication is defined as exposure to high levels of lead typically associated with severe health effects. Poisoning is a pattern of symptoms that occur with toxic effects from mild to high levels of exposure; toxicity is a wider spectrum of effects, including subclinical ones (those that do not cause symptoms) (Guidotfi and Ragain, 2007). The amount of lead in the blood and tissues, as well as the time course of exposure, determines toxicity. Lead poisoning may be acute (from intense exposure of short duration) or chronic (from repeat low-level exposure over a prolonged period), but the chronic is much more common (Rossi, 2008).

Diagnosis and treatment of lead exposure are based on blood lead level measured in micrograms of lead  perdeciliter of blood  (μg/dL). A blood lead level of 10 μg/dL or above is a cause for concern; however, lead may impair development and have harmful health effects even at lower levels, and there is no known safe exposure level (Barbosa, et al., 2005).