Cholinergic involvement in cobalt-induced epilepsy in the rat.
In rats with cobalt implanted in the right frontal cerebral cortex, acetylcholine (ACh) levels were depressed in the visually non-necotic, surrounding cortex at 7 and 14 days after surgery in comparison with values for controls treated with glass. At 21 days post-implantation, ACh levels were not different for glass and cobalt treatments. Effects of drugs affecting cholinergic function on electro-corticographic (ECoG) epileptiform activity were determined in rats implanted bilaterally with cobalt. The cholinesterase inhibitors, physostigmine and diisopropylfluorophosphate reduced both seizure activity and interictal spiking in these cobalt-treated rats. Hemicholinium-3 (HC-3), given subacutely initially inhibited seizures, but seizure frequency increased later during treatment. HC-3 did not appear to inhibit interictal spiking. These results suggest an involvement of brain cholinergic system in chronic cobalt experimental epilepsy. Seven days after cobalt implantation, HC-3 was less effective in depleting ACh in cerebral cortex adjacent to the cobalt-lesion than in similar tissue from rats with no cobalt implants. This suggests that the cholinergic neurons adjacent to the implant are not highly active at a time when seizure frequency is maximal.
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002540:Cerebral Cortex / Q000201:enzymology / Q000378:metabolism*; D002802:Cholinesterases / Q000032:analysis; D003035:Cobalt; D006426:Hemicholinium 3 / Q000494:pharmacology; D007531:Isoflurophate / Q000494:pharmacology; D008297:Male; D010433:Pentylenetetrazole / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D011950:Receptors, Cholinergic / Q000502:physiology; D012640:Seizures / Q000139:chemically induced* / Q000378:metabolism; D013997:Time Factors
D011950:Receptors, Cholinergic; D007531:Isoflurophate; D006426:Hemicholinium 3; D003035:Cobalt; D010830:Physostigmine; D002802:Cholinesterases; D000109:Acetylcholine; D010433:Pentylenetetrazole