AbstractThe effects of centrifuge-induced hypergravity on the presynaptic events have been investigated in order to provide further insight into regulation of glutamate and GABA neurotransmission and correlation between excitatory and inhibitory responses under artificial gravity conditions. Exposure of animals to hypergravity (centrifugation of rats at 10G for 1h) has been found to cause changes in the synaptic processes of brain, in particular neurotransmitter release and uptake in rat brain synaptosomes. Hypergravity loading resulted in more than two-fold enhancement of GABA transporter activity (Vmax increased from 1.4±0.3nmol/min/mg of protein in the control group to 3.3±0.59nmol/min/mg of protein for the animals exposed to hypergravity (P⩽0.05)). The maximal velocity of l-[14C]glutamate uptake decreased from 12.5±3.2 to 5.6±0.9nmol/min/mg of protein under artificial gravity conditions. Depolarization-evoked exocytotic release of the neurotransmitters has also changed in response to hypergravity. It increased for GABA (7.2±0.54% and 11.74±1.2% of total accumulated label for control and hypergravity, respectively (P⩽0.05)), but reduced for glutamate (14.4±0.7% and 6.2±1.9%, for control and hypergravity, respectively).Thus, comparative analysis of the neurotransmitter uptake and release has demonstrated that short-term centrifuge-induced 10G hypergravity loading intensified inhibitory and attenuated excitatory processes in nerve terminals. The activation or reduction of neurotransmitter uptake appeared to be coupled with similarly directed alterations of the neurotransmitter release.
Centrifuge-induced hypergravity: [3H]GABA and l-[14C]glutamate uptake, exocytosis and efflux mediated by high-affinity, sodium-dependent transporters
Advances in Space Research ; 36 , 7 ; 1340-1345
2005-10-04
6 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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