<prompt> Reduction in central___ plays a vital role in suicidal behavior.DopamineAcetylcholineSerotoninEpinephrine  <response>: Ans. c Serotonin Ref. Harrisons medicine 17th ed., 2717; Kaplan Sadocks Synopsis of Psychiatry, 10th ed., p. 901Biological Factors in Suicide Diminished central serotonin plays a role in suicidal behavior. Low concentrations of CSF 5-HIAA also predicts future suicidal behavior.ETIOLOGY AND PATHOPHYSIOLOGY OF SUICIDE There is some evidence that a functional polymorphism in the serotonin transporter 5-HTT gene may interact with stressful life events to markedly increase risk of depression and suicide. Postmortem examination of brains of suicide victims indicate altered noradrenergic activity, including increased binding to a1, - a2-, and b-adrenergic receptors in the cerebral cortex and decreased numbers of noradrenergic neurons in the locus coeruleus. Involvement of the serotonin system is suggested by findings of reduced plasma tryptophan levels, a decreased cerebrospinal fluid level of 5-hydroxyindolacetic acid the principal metabolite of serotonin in brain, and decreased platelet serotonergic transporter binding. An increase in brain serotonin receptors in suicide victims and decreased expression of the cyclic AMP response element-binding CREB protein are also reported. However, a decrement in mood after tryptophan reduction is considerably less robust in untreated patients, indicating that, if presynaptic serotonergic dysfunction occurs in depression, it likely plays a contributing rather than a causal role.DiseaseAssociated Change in NeuotransmitterSucidal behavior?HIAA and serotoninAnxiety NE, GABA, serotonin 5HT.DepressionNE and serotonin 5HT.Alzheimers dementiaACh.Huntingtons diseaseGABA, ACh.Schizophrenia dopamine.Parkinsons diseasedopamine, ACh.Educational point:NTCell BodiesTerminal locationNotesGlutamateGABACortexStriatumSpinal CordInter-neurons,Spinal CordAMPA Na, NMDA Ca, Ketamine, Stroke lschemiaAnticonvulsantsBarbiturateBenzodiazepineAnestheticsEtOHAchNucleus Basalis, SeptumCortex, HabenulaMemoryAlzheimersMyasthenia gravisDopamineSubstantia Nigra, VTACaudatePutamen, Limbic,Frontal Cortex,PituitaryParkinsonsDrug craving Psychosis ProlactinNELocus CoeruleusCortex Limbic-5-HTRaphe nucleiForebrainLow levels in suicidal behavior.Acts as inhibitor of pain pathways in the cord.Sleep.Acts an inhibitor in higher regions of CNS is believed to help control the mood.MigraineAnti-anxiety.Anti-psychosis.Anti-emetic.Opioid peptidesHypothalamusBasal gangliaPituitaryHypothalamusEndorphinEnkephalinDynorphin 