Enhancement of short-term synaptic plasticity by prior environmental stress

All chemical synapses can rapidly up- or down-regulate the strength of thei r connections to reshape the postsynaptic signal, thereby stressing the inf ormational importance of specific neural pathways. It is also true that an organism's environment can exert a powerful influence on all aspects of neu ral circuitry. We investigated the effect of a prior high-temperature stres s on the short-term plasticity of a neuromuscular synapse in the hindleg ti bial extensor muscle of Locusta migratoria. We found that the prior stress acted to precondition the synapse by increasing the upper temperature limit for synaptic transmission during a subsequent stressful exposure. As well, preexposure to a stressful high-temperature environment increased short-te rm facilitation of excitatory junction potentials concurrent with a decreas e in excitatory junction potential amplitude and a reduction in its tempora l parameters. We conclude that a stressful environment can modify synaptic physiological properties resulting in an enhancement of short-term plastici ty of the synapse.