Polyamines appear to be second messengers in mediating Ca2+ fluxes and neurotransmitter release in potassium-depolarized synaptosomes.
High potassium (50 mM) depolarization induces a rapid (less than 15 sec) increase in the levels of the polyamines putrescine, spermidine and spermine and their rate-regulating synthetic enzyme ornithine decarboxylase in synaptosomes from rat cerebral cortex. The ornithine decarboxylase inhibitor alpha-difluoromethylornithine blocked the K+-stimulated increase in enzyme activity and polyamines and also suppressed the increase in 45Ca2+ influx and efflux and the Ca2+-dependent release of GABA and norepinephrine. Added putrescine attenuated or negated the effects of alpha-difluoromethylornithine. These results suggest that enhanced polyamine synthesis is required for potassium depolarized stimulation of synaptic function.
Iqbal
Z
Z
Koenig
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002540:Cerebral Cortex / Q000201:enzymology / Q000378:metabolism; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D009955:Ornithine Decarboxylase / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D013574:Synaptosomes / Q000201:enzymology / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018377:Neurotransmitter Agents; D011073:Polyamines; D005680:gamma-Aminobutyric Acid; D009955:Ornithine Decarboxylase; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine