NTs 2 b Flashcards
neuropeptides: 5 categories
hypothalamic releasing hormones, neurohypophyseal hormones, pituitary peptides, gastrointestinal peptides, and other
neuropeptides act through what receptors?
heptahelical G protein and 2nd messengers. NOT ionotropic receptors. can also change ion fluxes.
neuropeptides: synthesis? rate, transport, abundance?
synthesized on ribosomes in cell bodies; rate controlled at cell body then peptide slowly transported to terminals via axonal transport and releasable peptide soon runs out
neuropeptides released by? characteristics of transmission
intense nerve activity: expensive but very effective and act over a wide area. volume transmission/slow synpatic potentials
peptides typically cleaved from? ex?
large precursor molecules by specific proteases. ex POMC into ACTH, b-LPH, a-MSH, edorphins and enkephalins, etc.
veiscles for neuropeptides vs. NTs
synaptic vesicle built around peptide as it is processed vs. conventional NTs are transported into vesicles
NTs into vesicles how?
proton pump (using ATP) makes inside very acidic. transmitter transporter: H+ leaves via concentration gradient, transmitter goes in
substance P: size? family?
11 amino acids. tackykinins: also includes neurokinin A and B
substance P involved in what 4 things
peristaltic reflex in enteric neurons. reflex pathways in prevertebral sympathetic ganglia. neurogenic inflammation (axon reflex) neuro-immune interactions
substance P in CNS: 2 roles
transfer of painful ino. anxiety, depression, emesis control (vomiting)
substance P actions outside NS (3)
arteriole vasodilator but constricts veins. constricts bronchioles and intestinal smooth muscle. salivary secretion.
substance P: therapeutic interventions?
non peptide antagonists developed as potential analgesics but work better as antidepressants
NPY: size? why called Y?
36 amino acids. rich in tyrosine = Y
NPY: main role for transmission
co-transmitter for NA in sympathetic nerves that control blood vessels (vasoconstriction)
NPY: in CNS?
involved in control of feeding and BP: intraventricular injection of NPY = feeding. maybe use antagonists for obesity treatment
2 NPY receptors and their transduction cascade and effect
Y1 receptors (like a1) G1 coupled, PLC, IP3, Ca for smooth muscle contraction. Y2 (like a2) Gi/o coupled, inhibit presynpatic Ca channel currents = decreased transmitter release (presynpatic)
3 opioid peptides
enkephalins. dynorphins. endorphins.
enkephalins: two examples and sizes? made from? distribution?
leucine and methionine enkephalins both chains of 5 aas. cleaved from larger 267 aa proenkephalin. in neurons widely distributed in the brain
dynorphins: size, made from
30 aa long. four smaller peptides derived from prodynorphin which is 257 aa long
endorphins: mainly found where?
imunoreactive cell bodies are mainly found in arcuate nucleus and periarcuate regions of hypothalamus. also found in brainstem + pit gland
opoid receptors: 3 types? category? also bind what drugs?
mu, delta, kappa. G protein coupled. morphine and heroin
mu-receptors (opioid) for?
important role in regulation of pain transmission in SC and CNS
opoid receptor stimulation causes what 6 things
analgesia. constipation. respiratory depression. euphoria. sedation. meiosis (pinpoint pupils, parasymp)
