ß-adrenergic receptor density and adenylate cyclase activity in lead-exposed rat brain after cessation of lead exposure
To understanding the reversible or irreversible harm to the -adrenergic system in the brain of lead-exposed rats, this study sets up an animal model to estimate the change in the sympathetic nervous system of brain after lead exposure was withdrawn. We address the following topics in this study: (a) the relationship between withdrawal time of lead exposure and brain -adrenergic receptor, blood lead level, and brain lead level in lead-exposed rats after lead exposure was stopped, and (b) the relationship between lead level and -adrenergic receptor and cyclic AMP (c-AMP) in brain. Wistar rats were chronically fed with 2% lead acetate and water for 2 months. Radioligand binding was assayed by a method that fulfilled strict criteria of -adrenergic receptor using the ligand [125I]iodocyanopindolol. The levels of lead were determined by electrothermal atomic absorption spectrometry. The c-AMP level was determined by radioimmunoassay. The results showed a close relationship between decreasing lead levels and increasing numbers of brain -adrenergic receptors and brain adenylate cyclase activity after lead exposure was withdrawn. The effect of lead exposure on the -adrenergic system of the brain is a partly reversible condition.