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Neurotransmitters
| Question | Answer |
|---|---|
| What can neurotransmitters be classified as? | Biologically active, non-standard amino acids |
| What does non-standard mean? | Derived from standard AA but have some alterations to the classifc AA structure |
| What is GABA derived from? | Glutamate |
| What is serotonin derived from? | Tryptophan |
| What is melatonin derived from? | Tryptophan |
| What is thyroid hormone derived from? | Tyrosine |
| What is histamine derived from? | Histidine |
| What is nitric oxide derived from? | Arginine |
| What are catecholamines derived from? | Tyrosine |
| Through what reaction do we get GABA from glutamate? | Decarboxylation using B6 |
| What is the enzyme in the conversion of glutamate to GABA? | Glutamate decarboxylase |
| What are two other common reactions catalyzed by this vitamin? | Transamination, desulfhydration |
| What is the function of GABA? | Inhibitory NT in brain - binds to GABA receptors leading to the opening of Cl channels and hyperpolarization of membrane |
| What drugs facilitate the effects of GABA? | Barbiturates and benzodiazepines |
| What are the effects of BDZs and benzodiazepams? | Anti-epileptics, anxiolytics, or sedative |
| How do we get serotonin from tryptophan? | Hydroxylation step which uses BH4 and decarboxylation step which uses B6 |
| What is BH4 | Folate-like molecule that assists with redox reactions |
| What is serotonin involved in? | Inhibition of feeding, elevation of mood, temperature regulation, perception of pain, induction of sleep |
| How have we been able to quantify serotonin in the inhibition of feeding? | High levels are implicated in anorexia nervosa and low levels in bulimia |
| How has serotonin levels been used to elevate mood? | In use of antidepressants (SSRI) |
| What drug has shown the temperature regulatory effects of serotonin? | MDMA uses serotonin and can lead to oveheating |
| What role does serotonin play in the GIT? | Causes GIT stimulation |
| What role does serotonin play in vasculature? | Functions in platelet aggregation, vasoconstriction |
| How do we get melatonin from serotonin | After tryptophan reaction to serotonin, methylation and acetylation to get melatonin |
| Where does the conversion of serotonin to melatonin happen? | Pineal gland |
| What does melatonin help with? | Regulation of sleep/wake cycles |
| How do we get thyroid hormones? | Complex mechanism that includes the addition of I's |
| What does T3 stand for? | Tri-iodo-thyronine |
| What is T4? | Thyroxine |
| What is the effect of T3? | Increase metabolic rate |
| How do we get histamine from histidine? | Via decarboxylation using B6 |
| What role does histamine have on the CNS? | Promotes wakefulness via H1 receptors |
| What is a related side effect of some antihistamines, like benadryl? Why do some others like Claritin not have this effect | Drowsiness. Doesn't cross BBB |
| What role does histamine have on the immunological system? | Mediates allergic responses via H1 receptors by releasing mast cells in response to allergens |
| What is the allergic response? | Bronchoconstriction and vasodilation. If severe, can cause anaphylactic shock |
| What role does histamine have on the stomach? | Promotes secretion of gastric acid via H2 receptors |
| What is the function of nitric oxide? | Vasodilator and inhibitor of blood clotting. NO also acts as a retrograde NT for glutamate release |
| How does NO act as a retrograde NT for glutamate release? | Glu causes post-synaptic calcium influx in neurons which is linked to NO synthesis and release which causes further presynaptic release of Glu |
| What is linked to learning and memory? | Nitric oxide - glutamate release |
| What is the common structural features of catecholamines | Benzene with two hydroxyl groups and an amine group |
| What are examples of catecholamines? | Dopamine, norepinephrine, epinephrine |
| How is tyrosine converted to dopamine? | Hydroxylation via BH4 and decarboxylation via B6 |
| How is norepinephrine derived from dopamine? | Hydroxylated via B6 and Vit C |
| How is epinephrine derived from norepinephrine? | Methylation via B9/B12 - SAM |
| What kind of effect does NE/E have on the PNS? | Sympathetic mediators for body's response to stress - fight or flight |
| What kind of effect does NE/E have on the CNS? | Stimulatory NT in CNS |
| What can overstimulation of the CNS lead to? | Anxiety, fear, tension, headache, tremor |
| What role does dopamine have on the body? | Acts as prolactin inhibitory hormone, stimulatory NT in CNS, important in movement |
| What is the function of prolactin? | Hormone secreted by pituitary gland that stimulate milk production |
| What kind of stimulatory effect does dopamine have on CNS? | Stimulates pleasure/reward centers - is the basis of many recreational drugs (nicotine, cocaine, amphetamines) |
| What disease is characterized by a deficiency in dopamine? | Parkinson's |
| How are catecholamines metabolized? | MAO or COMT |
| What is MAO? | monoamide oxidase - oxidizes amine group using FAD as cozenzyme |
| What is COMT? | Catechol-O-methyltransferase - methylates hydroxy group from SAM (B9/B12) |
| What are special peptide? | Biologically active molecules made from short strings of AAs |
| What are examples of special peptides? | Glutathione; NPY, galanin vs alpha-MSH, CCK; ADH vs ANF; Substance P, bradykinin vs enkephalins |
| What is NPY, galanin, alpha-MSH, and CCK involved in? | Appetite |
| What is ADH and ANF involved in? | Blood pressure |
| What is substance P, bradykinins, and enkeohalins involved in? | Pain perceptions |
| What is glutathione? | Gamma-glutamylcysteinylglycine - glutamate, cysteine, and glycine |
| What are the four general functions of glutathione? | Antioxidant, detoxification, synthesis of eicosanoid LTC4, and movement of AA especially S on cysteine |
| What two NTs are involved in stimulating appetite? | Neuropeptide Y and galanine |
| How does neuropeptide Y stimulate appetite? | In high levels upon waking in morning, dieting, and fasting - use of carbs as fuel → increases carb instake |
| How does galanin stimulate appetite? | High levels later in day or when preparing to fast - use of fats for fuel → increases fat intake |
| What NTs are involved in inhibiting appetite? | CCL, alpha-MSH, and leptin |
| What is CCK | Cholecystokinin - in response to fat and protein intake |
| What is alpha-MSH? | alpha-melanocyte stimulating hormone |
| What stimulates alpha-MSH release? | Leptin release from adipose cells in response to increased adipose tissue mass |
| In addition to stimulating alpha-MSH release, what other function does leptin have? | Decrease expression of NPY and galanin |
| Given the effects leptin has, why isn't it useful as an anti-obesity drug? | Reduces appetite but not associated with weight loss |
| What peptides stimulate pain perception? | Bradykinin and substance P |
| How does bradykinin stimulate pain perception? | Released from damaged vessels and activates sensory neurons |
| How does substance P stimulate pain perception? | Transmits pain signals up spinal cord to brain |
| What peptides decrease pain perception? | Enkephalins |
| What are the two types of enkephalins? | Met-/Leu-enkephalins |
| What is the structure of enkephalins | Tyr-Gly-Gly-Phe-(Met or Leu) |
| How do enkephalins decrease pain perception? | Bind to opioid receptors which leads to decreased release of substance P → decreased transmission of pain signals up spinal cord |
| What other NT can inhibit pain signals? | Serotonin can decrease transmission of pain by activating inhibitory interneurons in the pain pathway and block substance P release |
Created by:
nnguyen44