BIOL 460 1st Edition Lecture 1 Outline of Lecture I Monoamine Neurotransmitters and their mechanisms II Anatomy of the Brain III What each monoamine neurotransmitter does Monoamine Neurotransmitters NTMs released at synapse 1 Contain an amino group connected to an aromatic ring by a 2 carbon chain 2 Includes a Serotonin derived from tryptophan b Catecholamines derived from tyrosine i Dopamine ii Epinephrine iii Norepinephrine iv Catechol group aromatic ring with to hydroxyl groups 3 When monoamine NTMS are released they must be removed or destroyed so receptors aren t always on a One way Monoamine oxidase MAO in cytoplasm of terminal bouton b Transport proteins in terminal bouton c Reuptake of monoamines into cytoplasm via facilitated diffusion broken down by MAO d Several drugs prevent dopamine reuptake by blocking the transport protein cocaine 4 Catecholamine NTMs can also be inactivated in the cytoplasm of postsynaptic cells a Transporter takes catecholamine up into cell b Inactivated by catechol o methyl transferase COMT adds methyl group 5 Mechanism of action see figure 7 31 possible essay question a monoamine bonds to receptor b G protein is used as second messenger c Alpha subunit turns on adenylate cyclase converting ATP to cyclic adenosine monophosphate cAMP and pyrophosphate PO4 PO4 d cAMP is a very common 2nd messenger e cAMP activates protein kinase which add a phosphate to a protein phosphorylates the protein i phosphates are strongly polar ii alters protein conformation makes protein active can be an ion channel or enzyme f g h i 6 What a b c 1 kinase is inactive because kinase is a dimer 2 partsregulatory subunit more affinity for cAMP than catalytic part of protein kinase g protein turns itself off monoamine inactivates by MAO or COMT if catecholamine cAMP broken down by phosphodiesterase protein phosphatases reverse action of protein kinases monoamine NTMs do Brain anatomy of subphylum vertebrata Five regions of the brain front to back i Telencephalon 1 Largest part in mammals and birds 2 Cerebral hemispheres cerebrum limbic system 3 Cerebral cortex a Layer of gray matter on surface of cerebral hemisphere b On outside more surface area c White matter inside ii Diencephalon 1 Neck region 2 Top epithalamus pineal gland 3 Middle walls thalamus a Relay station b Sends signals to telencephalon 4 Bottom hypothalamus a Contains basal nuclei b Autonomic nervous system c Pituitary gland dangle from bottom iii Mesencephalon mid brain 1 Roof tectum vision in fishes 2 Floor tegmentum iv Metencephlaon unconscious control 1 Cerebellum mid cerebrum a Little brain b Refines movement of skeletal muscle c Gray matter on outside d White matter on inside arbor vitae 2 Pons fiber tract convey info back and forth from cerebrum to cerebellum a Relay station b Spinal cord telencephalon c Contains Raphe nuclei v Myelencephalon 1 Medulla oblongata brainstem 2 Centers controls ANS a Respiratory center b Cardiac center Serotonin i Synthesized from tryptophan ii Contains indole ring instead of catechol group iii LSD is an agonist for serotonin also has indole group 1 Affects mood and emotion 2 Can learn about endogenous NTMs by discovering agonists drugs and poisons iv Serotonergic neurons receptors that bond to serotonin 1 Raphe nucleus in pons 2 Sends projections axons to telencephalon v Affect mood behavior sleep appetite and circulation 1 Lots of effects because there are several types of serotonin receptors 2 Each receptor has its own effect 3 Migraine are caused by vasoconstriction of brain arteries vi Biochemistry of depression 1 Zoloft Paxil Prozac Luvox SSRIs serotonin specific reuptake inhibitors a Inhibits reuptake of serotonin into terminal bouton extends effect of serotonin release d Dopamine i tyrosine DOPA dopamine ii dopaminergic neurons 1 nigrostriatial dopamine system a cell bodies in substantia nigra i nigra black ii named after dark color of substantia nigra iii dark because of melanin pigment produced as byproduct of dopamine synthesis b project into basal nuclei of telencephalon c one projection axon is corpus striatum nigrostriatial dopamine system d involved in initiation of skeletal muscle movement e Parkinson s Disease i Dopaminergic neurons degenerate ii Treatment L DOPA precursor to dopamine that can cross blood brain barrier iii Fatal disease iv Also given MAO and COMT inhibitors to prevent dopamine breakdown