Regional Brain and Pituitary Cyclic Nucleotide Response Following Central Cholinergic Stimulation in Rats Chronically Exposed to Lead.

摘要

Long Evans rats were exposed continuously to lead (1,000ppm) throughout gestation, nursing and up to sacrifice at 60 days of age. A matched group of control animals were exposed to distilled water. On the day of sacrifice, control and lead treated animals were administered methylatropine 40 minutes and oxotremorine (2mg/kg) 10 minutes prior to sacrifice by microwave irradiation. Locomotor activity was monitored during the 10 minutes immediately preceding sacrifice. Levels of cyclic AMP and cyclic GMP were determined in 21 brain regions by radioimmunoassay. Locomotor activity following oxotremorine was significantly reduced in both lead treated and control animals. Levels of cyclic GMP were increased in septal region and frontal cortex and reduced in cerebellum and inferior colliculus of both groups of animals. The levels of cyclic AMP in the pituitary increased 20-25 fold, with greater response noted in lead-treated rats. Elevations of cyclic AMP were also noted in both groups in the interpeduncular nucleus, corpus striatum and substantia nigra. These data suggest that in the central nervous system, other than the pituitary, the cellular response to a muscarinic agonist is not significantly affected by chronic exposure to lead.