Neuropeptides & Drugs 1 Flashcards
test 4 material
how are neuropeptides synthesized and released?
pre-propeptides with a signaling sequence are attached to the ER, activating the signaling sequence converts them into propeptides and then they are broken up into peptides, they are then packaged into dense-core vesicles then undergo cleavage and post-translational modification, they are co-released in the synapse with other NT, bind to metabotropic receptors
what is the termination of action of neuropeptides?
they are degraded by peptidases since they are too large for reuptake
what are the 5 classes of neuropeptides?
- brain-gut peptides
- pituitary peptides
- hypothalamic releasing peptides
- miscellaneous peptides
- endogenous opiates
what are some examples of brain-gut peptides?
secreted by the brain and the GI track, include substance P (pain perception in the periaqueductal gray, peristalsis) and cholecystokinin and vasointestinal peptides (feeding, satiation, and appetite)
what are some examples of pituitary peptides?
oxytocin (bonding in humans, uterine contractions, lactation) and vasopressin (male bonding in prairie voles)
what are some examples of hypothalamic releasing peptides?
leutenizing hormone releasing hormone (LHRH) for sexual development and fertility
what are some examples of miscellaneous peptides?
neuropeptide Y (feeding)
posterior vs anterior pituitary glands?
posterior: cell bodies are in the hypothalamus and terminals in the posterior pituitary gland for release of oxytocin and vasopressin
anterior: peptides are produced in the anterior pituitary gland and the endocrine cells release endorphins, growth hormone, PRL, FSH and LH, ACTH, and TSH
what are the types of endogenous opiates and their preferred receptors?
endorphins bind to mu, dynorphins bind to kappa, and enkephalins bind to delta opioid receptors
what is the function of endogenous opiates and what are some examples?
function in euphoria, analgesia, sedation, antitussive (reduces coughing), and anti-diarrhea examples include runner’s high, post-traumatic analgesia, placebo analgesia, and opiate addiction
what are some drugs that act on opioid receptors?
morphine/heroin/fentanyl: direct mu opioid receptor agonists that mimic endorphins
naloxone/naltrexone: direct mu antagonist
salvinorin A: direct kappa agonist
imodium: peripheral opioid receptor agonist
where in the body are mu opioid receptors located?
in the brain, spinal cord, GI tract, sensory neurons, and immune cells
how does chronic opioid use affect mu receptors?
the opioid receptor becomes desensitized and B-arrestin internalizes the receptor leading to reduced signaling, eventually the receptor will be degraded inside the cell and there will be increased levels of adenylate cyclate, PKC, PKA, and NMDA which will cause hyperalgesia
