Polyamine transport, accumulation, and release in brain.
Cycling of polyamines (spermine and spermidine) in the brain was examined by measuring polyamine transport in synaptic vesicles, synaptosomes and glial cells, and the release of spermine from hippocampal slices. It was found that membrane potential-dependent polyamine transport systems exist in synaptosomes and glial cells, and a proton gradient-dependent polyamine transport system exists in synaptic vesicles. The glial cell transporter had high affinities for both spermine and spermidine, whereas the transporters in synaptosomes and synaptic vesicles had a much higher affinity for spermine than for spermidine. Polyamine transport by synaptosomes was inhibited by putrescine, agmatine, histidine, and histamine. Transport by glial cells was also inhibited by these four compounds and additionally by norepinephrine. On the other hand, polyamine transport by synaptic vesicles was inhibited only by putrescine and histamine. These results suggest that the polyamine transporters present in glial cells, neurons, and synaptic vesicles each have different properties and are, presumably, different molecular entities. Spermine was found to be accumulated in synaptic vesicles and was released from rat hippocampal slices by depolarization using a high concentration of KCl. Polyamines, in particular spermine, may function as neuromodulators in the brain.
Masuko
Takashi
T
Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
Kusama-Eguchi
Kuniko
K
Sakata
Kaori
K
Kusama
Tadashi
T
Chaki
Shigeyuki
S
Okuyama
Shigeru
S
Williams
Keith
K
Kashiwagi
Keiko
K
Igarashi
Kazuei
K
D000818:Animals; D015317:Biogenic Polyamines / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D001923:Brain Chemistry; D002478:Cells, Cultured; D006624:Hippocampus / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013095:Spermidine / Q000378:metabolism; D013096:Spermine / Q000378:metabolism; D013572:Synaptic Vesicles / Q000737:chemistry / Q000378:metabolism; D013574:Synaptosomes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism
D015317:Biogenic Polyamines; D013096:Spermine; D013095:Spermidine