Chapter 6 taught new things about neurotransmitters, for example that they are assorted in three major classes: amino acids, amines, peptides. They must have three identifiable features for the molecule to be a neurotransmitter. First, the molecule must be stored in the presynaptic neuron and synthesized there. Second, during the stimulation the presynaptic axon terminal release the molecule. Third, the presynaptic neuron releases a neurotransmitter and produces the response. After that the molecule must make a response in postsynaptic cell, which mimics the response of the neurotransmitter.
The neurotransmitters can be localized in several ways. One way is immunochemistry where the transmitter candidate can cause an immune response that generates specific antibodies which be chemically tagged with colourful marker. After this the antibodies are injected to brain tissue section. They highlight cell types that have the specific transmitters. Molecules can be localized by the different antibodies that are marked with different colours.
Other method is called in situ hybridization, ISH. The method finds the specific mRNA strands by binding complementary nuclei acid strands to these mRNA strands. Every polypeptide synthesize has unique mRNA molecule. In the method can be used colourful fluorescent molecules, then it is called FISH. The third alternative is to make the probes radioactive. Then we can monitor the distribution of radioactivity. This method is called autoradiography.
It was interesting to read about the different neurotransmitters, specially catecholamines and serotonin, and their limiting factors. The structures of different neurotransmitters are quite complex and their synthesizations are also quite hard to remember.
The most interesting part of the chapter was the one about G-protein coupled receptors and effectors because it gathered well the previously learned information about it but also explained well the new ones. For example, the shortcut pathway and second messenger cascades clarified well, how the different G-protein-coupled receptors affect on different effector proteins.
The chapter taught in its entirety that the neurotransmitters are small parts of huge chain of events. Neurotransmitters causes fast and slow chemical changes and some of them can active more than one subtype of receptor while some of the neurotransmitters have their own receptors but converge to affect the same effector system.