Quiz 3 Flashcards
What are some functions of serotonergic pathways in the brain?
Found in CNS (raphe nuclei of the brainstem)
Influence mood, appetite, sleep, cognition, memory, thermoregulation, nausea
What cells make 90% of the serotonin in the body?
Enterochromaffin cells of the GI tract
- What is the effect of serotonin on the GI?
a. Stimulate myenteric neurons → ↑GI motility
b. Release of 5-HT → acts on vagal afferents → nausea
c. Gut immune response(?)
- What is the function of serotonin stored in platelets?
a. Released from PLT → vasoconstriction, PLT aggregation, clot formation
- What conditions are treated with therapies that increase serotonin?
a. Depression, anxiety, insomnia, OCD, migraines, aggression
- What are the symptoms of serotonin syndrome?
a. Cognitive: HA, agitation, hypomania, mental confusion, hallucinations
b. Autonomic: HTN, hyperthermia, shivering, sweating, N, D
c. Somatic: tremor, hyperreflexia, myoclonus
- What is carcinoid syndrome?
a. Disorder caused by tumors of the enterochromaffin cells secreting excess serotonin
b. SXS: D, flushing, dyspnea, abd. pain
- What is the rate-limiting step in serotonin synthesis? What is this most dependent upon?
a. Tryptophan → 5-HTP
b. Dependent on tryptophan concentration
- Why might giving someone tryptophan result in a decrease in catecholamines?
a. The enzyme used to convert 5-HTP into serotonin (dopa decarboxylase) is the same enzyme used in catecholamine synthesis. Increasing the pool of tryptophan reduces the amount of dopa decarboxylase available for catecholamine synthesis.
- How is 5-HT neurotransmission terminated?
a. 5-HT is removed from synaptic cleft via reuptake system, similar to catecholamines.
b. SSRIs inhibit this reuptake
- Why should MAO inhibitors not be given at the same time as selective serotonin uptake inhibitors (SSRIs)?
a. 5-HT is degraded by MAO → MAO inhibitors → ↑5-HT → ↑Serotonin
b. Combining an MAO inhibitor with an SSRI can cause serotonin syndrome
- What are some conditions that are treated with 5-HT receptor agonists?
a. Migraines (triptans), anxiety (Buspar)
- What are some conditions that are treated with 5-HT receptor antagonists?
a. Schizophrenia (Risperidone), N/V (Zofran, Metoclopramide)
- What is the main inhibitory neurotransmitter in the CNS?
a. GABA
- What are effects of GABA?
a. Sedative/hypnotic, anti-anxiety, and anti-convulsive effects
- How are substances that increase GABA activity used?
a. Seizure d/o, anxiety d/o, insomnia
- How are substances that decrease GABA activity used?
a. Antidote for OD of GABA agonist
- What amino acid is the precursor for GABA?
a. Glutamate
- In addition to the binding site for GABA, what other binding sites exist on the GABAA receptor?
a. Binding sites for benzodiazepines, barbiturates, ethanol
- Where do many of the nervine herbs bind on the GABAA receptor?
a. Benzodiazepine receptor site
- What is the main excitatory neurotransmitter in the CNS?
a. Glutamate
- What is the excitotoxicity theory?
a. Prolonged or repeated depolarization of a neuron d/t glutamate stimulation → cell damage and death
- What is the immediate precursor for glutamate in the brain?
a. Glutamine
- How is glutamate neurotransmission terminated?
a. Rapidly taken back up into neurons and astrocytes after release
- What are some endogenous opioids?
a. Endorphins, Enkephalins, Dynorphins
- What are endogenous opioids involved in?
a. Pain suppression, reward, mood, motor coordination, feeding, body temperature, immune response, stress response