Opiates (exam 3)

PSYC 733

Laudanum

opium-based medicinal drink from the 19th century

Anti-tussive

cough suppressant

Anti-nociceptive

pain management

Naloxone

aka Narcan
synthetically derived antagonist used to treat opioid OD

how do opiates influence synaptic transmission?

opiates bind to opioid receptors in the brain (mu, delta, and kappa) to inhibit adenylyl cyclase and cAMP

fast vs slow pain pathway (anatomy and function)

• fast pain pathway: sensory information—> withdrawal/escape from stimulus (spinothalamic tract)

  • A delta fibers

  • dorsal horn

• slow pain pathway: affective processing of pain (C-fibers)

  • dorsal horn

  • PAG

  • cold sweat, decreased blood pressure

mu receptors: function and distribution

• found in areas related to analgesia (thalamus, PAG, SC, raphe nucleus)

• reinforcement: NA

• CV, respiratory control, emesis: brain stem

• sensorimotor integration: thalamus, striatum

delta receptors: function and distribution

• mostly in neocortex, striatum, olfactory areas, SN, and NAcc

• suggests role in olfaction, reinforcement, cognition, and modulation of analgesia

kappa receptors: function and distribution

• hypothalamus and pituitary

• may regulate pain perception, gut motility, water balance, and temp control

how does catecholamine depletion influence self-administration of opiates?

6-OHDA lesions DO NOT completely abolish self-administration

• suggesting something else contributes to addictiveness

what are clinical uses of opiates?

• anti-nociceptive (stop pain)

• anti-tussive (stop coughing)

• decreased gut motility (stop diarrhea)

what are the behavioral effects of opiates?

• respiratory depression

• pinpoint pupils

• drowsiness

• decreased appetite

• decreased ex drive

• vomiting

• self-administration

what are the effects of kappa and mu agonists on conditioned place studies?

• mu: CPP

• kappa: CPA

what are the effects of b-endorphins on the mesolimbic system?

disinhibition of VTA neurons

• inhibit inhibitory neurons (GABA) to increase DA

• like a double negative

how does dynorphin impact the mesolimbic system?

decrease DA release in NAcc (aversive effects)

how do kappa agonists impact the mesolimbic system

decrease DA release in NAcc (aversive effects)

effects of PZM21 vs morphine (analgesia, constipation, respiratory depression, CPP)

• decreases pain sensation

• not as much constipation and respiratory depression as morphine

• safer replacement for morphine (probably not very addictive)

which NTs are sometimes co-released with endogenous opioids?

• ACh

• GABA

• 5-HT

• CA (NE, epi, DA)

how do the acute effects of opioids differ from the rebound withdrawal symptoms?

withdrawal symptoms are basically the opposite of the acute actions (acute = pain relief, euphoria, and relaxation; rebound withdrawal = increased pain, anxiety, and agitation.

psychological and physiological effects of opiates

• physical withdrawal symptoms

• classical conditioning

• pharmacodynamic changes

• metabolic changes

• tolerance only for some effects

clonidine

medication used for high blood pressure

why is clonidine used in relation to opioids?

can be used to manage symptoms of opioid withdrawal (reduces SNS activity)

how is opiate addiction treated?

• withdrawal symptoms managed after detox w/ methadone (synthetic agonist that decreases craving)

• LAAM: agonist

• Buprenorphine: agonist/antagonist

• Narcan: antagonist