title: Polyamine amides are neuroprotective in cerebellar granule cell cultures challenged with excitatory amino acids.
abstract: Primary cultures of rat cerebellar granule cells have been used to assess the potential neuroprotective effects of philanthotoxins and argiotoxin-636 (ArgTX-636). These polyamine amides are potent antagonists of ionotropic L-glutamate (L-Glu) receptors. In granule cells loaded with fluo-3, ArgTX-636 and philanthotoxin-343 (PhTX-343) antagonised increases of intracellular free calcium concentration ([Ca2+]i) that were stimulated by N-methyl-D-aspartate (NMDA). The antagonism was use-dependent. Antagonism by PhTX-343 was fully reversible, but recovery following antagonism by ArgTX-636 was slow and only partial during the time-course of an experiment. Neither compound inhibited K(+)-induced increases in [Ca2+]i. In excitotoxicity studies with cerebellar granule cells, the release of lactate dehydrogenase (LDH) and morphological observations were used to assess cell death. A 20-30 min exposure to 500 microM NMDA, 100 microM L-Glu or 500 microM kainate was sufficient to kill > 90% of the cells after 18-20 h. When added 5 min prior to, and during agonist exposure, PhTX-343 and ArgTX-636 provided total neuroprotection. ArgTX-636 was about 20-30 fold more potent than PhTX-343 against NMDA, but was approximately equipotent with PhTX-343 against a kainate challenge. Neither of the toxins showed any inherent toxicity even at 400 microM and 100 microM respectively. Some analogues of PhTX-343 are more potent, both in terms of antagonism of NMDA-stimulated increases of [Ca2+]i and neuroprotection, than PhTX-343 and ArgTX-636.
authors: Department of Life Science, University of Nottingham, University Park, UK.
authors: A C
authors: AC
authors: Green
authors: K
authors: K
authors: Nakanishi
authors: P N
authors: PN
authors: Usherwood
mesh_terms: D000577:Amides; D000818:Animals; D001180:Arthropod Venoms / Q000633:toxicity; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects; D002531:Cerebellum / Q000166:cytology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018698:Glutamic Acid / Q000494:pharmacology; D007210:Indoleacetic Acids; D007608:Kainic Acid / Q000494:pharmacology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010636:Phenols / Q000633:toxicity*; D010648:Phenylacetates / Q000494:pharmacology*; D011073:Polyamines / Q000494:pharmacology* / Q000633:toxicity*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013111:Spider Venoms / Q000494:pharmacology
chemical_list: D000577:Amides; D001180:Arthropod Venoms; D018690:Excitatory Amino Acid Agonists; D007210:Indoleacetic Acids; D018696:Neuroprotective Agents; D010636:Phenols; D010648:Phenylacetates; D011073:Polyamines; D013111:Spider Venoms; C558368:argiotoxin-636; C074003:philanthotoxin 343; D018698:Glutamic Acid; D016202:N-Methylaspartate; D011188:Potassium; D007608:Kainic Acid; D002118:Calcium