Introduction 3. Neurotransmitter receptors 3.1. Gamma-aminobutyric acid type A receptors (GABA A-Rs) 3.1.1. Gene knockout of the beta 3 subunit of the GABA A-R 3.1.2. Gene knockout of the gamma 2 subunit of the GABA A-R 3.1.3. Gene knockout of the long splice variant of the gamma 2 subunit of the GABA A-R 3.1.4. Gene knockout of the alpha 6 subunit of the GABA A-R 3.2. Serotonin receptors 3.2.1. Gene knockout of the serotonin 5-HT 1B receptor 3.3. Opiate receptors 3.3.1 Gene knockout of the opiate mu receptor 3.4. Alpha adrenergic receptors 3.4.1. Point mutation of the alpha-2a adrenergic receptor 3.4.2. Gene knockout of the alpha-2b adrenergic receptor 3.4.3. Gene knockout and overexpression of the alpha-2c adrenergic receptor 3.5. Dopamine receptors 3.5.1. Gene knockout of the dopamine D1 receptor 3.5.2. Gene knockout of the dopamine D2 receptor 3.5.3. Gene knockout of the dopamine D3 receptor 3.5.4. Gene knockout of the dopamine D4 receptor 4. Kinases 4.1. Gene knockout of fyn tyrosine kinase 4.2. Gene knockout of the gamma isoform of protein kinase C 5. Neurotransmitters 5.1. Nitric oxide 5.1.1 Gene knockout of neuronal nitric oxide synthase 6. Perspectives 7. Acknowledgements 8. References