Opiate Receptors and the Neurochemical Actions of Opiates

Question 1

Mu receptors

Answer 1

• involved in the euphoric, analgesia, respiratory depression and physical dependence
• in the VTA opiate occupation of Mu receptors lead to the inhibition of GABA neurons which would normally inhibit dopamine neurons in the nucleus accumbens - this leads to the disinhibition of dopamine neurons in the nucleus accumbens and the resulting increase in dopamine underlies the rewarding effects of opiates

Question 2

Sigma Receptors

Answer 2

• mediate dysphoria and hallucination (PCP and DM expert effects on these receptors)

Question 3

Delta Receptors

Answer 3

• main backup opiate receptor and seems to cooperate with Mu receptors in producing most opiate effects

Question 4

Endogenous receptor ligand

Answer 4

• specific opiate receptors suggest that this exists bc it is unlikely that specific receptors would exist to interact solely with exogenously administered opiates

Question 5

Endorphins

Answer 5

• implicated in stress-induced algesia, acupuncture, childbirth, intense physical activity, sex and anorexia
• one way to determine if endorphins may be involved in some phenomena is to see if the behaviour affected by the administration of naloxone