DIFFERENT FUNCTIONAL POOLS OF ACETYLCHOLINESTERASE INDUCE CHANGES IN RAT LOCUS-CERULEUS NORADRENALINE METABOLISM

The effects of acetylcholinesterase (AChE) inhibition in the locus coeruleus (LC) were studied in rats utilizing fasciculin (FAS) and BW248c51 (BW). Both inhibitors were stereotaxically injected into the right LC and the animals were sacrificed 24 h later. Similar groups received atropine (30 mg/kg i.p.) every 5 h during 24 h. Another group of FAS-treated rats received naloxone twice (5 mg/kg i.p.) in 24 h. Other groups of FAS-treated rats were sacrificed 3 and 7 days after injection. An inhibition of 70% of LC AChE activity was observed 24 h after FAS or BW injection. Either FAS or BW induced a significant increase in NA levels in the injected LC compared to control values. Atropine treatment failed to block the FAS effect but it was able to counteract the BW-induced NA increase. NA levels were still increased 3 days after FAS treatment and returned to control values at day 7.