SUMMARY1. Transmitter release at neuromuscular junctions of extensor digitorum longus (EDL) muscle in mice was studied after 2-8 month periods of unforced running in wrheels.2. Intracellular recordings at 10 Hz stimulation revealed that the quantal content of endplate potentials (EPPs) in Mg2+-blocked preparations was larger by 30% in trained (mean number of quanta, m = 175+019, n = 7) than in untrained control EDL muscles (m = 135+0-35, n = 7). Similarly the amplitudes of the first, maximum and plateau EPPs during tetanic stimulation (100 Hz for 1 s or 400 ms) in curare-blocked preparations were increased by 28 % each; muscle fibre diameters did not differ while other postsynaptic effects were not excluded.3. Training effects became particularly evident in two pairs of monozygotic twins, in which the time courses of facilitation and depression were changed as well: at 100 Hz stimulation the maximum EPP amplitude was reached on average at 2-6 impulses in controls but at 2 0 impulses in runners, and the following decline below the value of the first EPP at 5 0 and 3-8 impulses respectively.4. Block resistance, as monitored by isometric tension measurements in different presynaptic (Mg2+) and postsynaptic (curare) blocking solutions, was higher in trained than in control EDL muscles. Depression in a train of four nerve-evoked single twitches at 2 Hz was lower.5. As expected from the unchanged fibre diameters (see above) isometric tetanic force was similar in trained and control EDL muscles. Muscle fatigue resistance was larger in trained animals and succinic dehydrogenase activity was higher in fibres of trained muscles indicating an endurance training of the EDL muscle.6. It is concluded that besides changes in muscle fibre properties, prolonged elevated activity causes increased transmitter release in EDL muscles. As a consequence, the safety margin of transmission in trained EDL muscles is markedly elevated.

Background Complex regional pain syndrome (CRPS) is a multifactorial disorder with complex aetiology and pathogenesis. At the outpatient pain clinic of Magdeburg University Hospital, all patients, without exception, are subject to permanent psychiatric care delivered by a consultation-liaison psychiatrist. In CRPS, psychological stabilization and treatment of the neuropathic aspects are equally important. The aim of this single-center retrospective study was to determine mental/psychiatric defects impairing pain processing at the time of investigation and show the effects of treating mental disorders and neuropathic pain with the same psychotropic drugs. Method On admission, the consultation-liaison psychiatrist examined the mental state of every patient in a semistructured interview according to AMDP (working group for methods and documentation in psychiatry). Due to the model of the Department of Anaesthesiology, we are able to compare the group of CRPS patients with all other outpatients treated for pain. Results The medical treatment of psychiatric dysfunction leads to an analgesic effect. Only every second CRPS patient had an additional psychiatric diagnosis, and 15.6% were diagnosed with depressive mood disorders and show a higher prevalence of depressive symptoms than the general population and exceed the mean for all patients treated in our pain clinic. Conclusions In neuropathies, treatment of the neuropathic pain has a modulating effect on mental disorders. As CRPS patients are frequently affected by depressions, and owing to the connection between depression and suicidal tendencies, patients should be seen by a consultation-liaison psychiatrist, and nonpsychiatrists should pay special attention to this patient group.

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The consequent application of established guidelines (according to WHO scheme) and the WHO index leads to a qualitative and measurable improvement of drug therapy for cancer-related pain.

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