Changes in cerebellar amino acid neurotransmitter concentrations and receptors following administration of the neurotoxin L-2-chloropropionic acid.
1p4studied the effect of L-2-chloropropionic acid (L-CPA)-induced (250 mg/kg/po/day for 3 days) neurotoxicity, which results in an almost total destruction of cerebellar granule cells over 5 days, on forebrain and cerebellar neurochemistry. There was a reduction in cerebellar aspartate and glutamate concentrations of L-CPA-treated rats and a reduction in N-methyl-D-aspartate (NMDA) and kainate receptor densities in the cerebellar cortex following loss of the granule cells. Concentrations of glutamine and GABA were increased transiently during the development of the granule cell lesion but fell back to control levels by Day 5 of the study. Glycine concentrations began to rise as the granule cells began to disappear and concentrations remained elevated until the end of the study. In contrast, concentrations of taurine began to fall around the same time point as the granule cells were gradually depleted. We did not observe any consistent changes in forebrain amino acid concentrations following the L-CPA administration or any changes in NMDA, kainate, GABAA, or A1-adenosine receptor densities. We therefore conclude that the L-CPA-induced loss in cerebellar granule cells is accompanied by a reduction in cerebellar aspartate and glutamate concentrations and in the density of NMDA and kainate receptors in the cerebellar cortex. Changes in cerebellar GABA, glutamine, glycine, and taurine concentrations probably reflect secondary compensatory changes in cerebellar activity resulting from a widespread loss of cerebellar granule cells and loss of excitatory inputs. We suggest that L-CPA-induced neurotoxicity may be valuable tool to study cerebellar neurochemistry and physiology.
Widdowson
P S
PS
Neurotoxicology Group, Zeneca Central Toxicology Laboratory, Macclesfield, Cheshire, United Kingdom.
Gyte
A
A
Simpson
M G
MG
Wyatt
I
I
Lock
E A
EA
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001345:Autoradiography; D001665:Binding Sites; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D006843:Hydrocarbons, Chlorinated; D008297:Male; D009498:Neurotoxins / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011422:Propionates / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013237:Stereoisomerism; D009435:Synaptic Transmission / Q000187:drug effects; D013654:Taurine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000596:Amino Acids; D001224:Aspartic Acid; D018698:Glutamic Acid; D005973:Glutamine; D005998:Glycine; D006843:Hydrocarbons, Chlorinated; D009498:Neurotoxins; D018377:Neurotransmitter Agents; D011422:Propionates; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D013654:Taurine; D005680:gamma-Aminobutyric Acid; C021974:2-chloropropionic acid