Week 7 HW Assignment: Questions about Opiorphin Reading
1. What is the three classes of endogenous compounds whose anti-nociceptive activity is
mimicked by opioid drugs?
Opiorphin, sialorphin, and spinorphin are the three types of endogenous substances whose pain-
relieving effects are comparable to those of opioid medications.These substances are all
endogenous enkephalinase inhibitors (EIs) The function of these three EIs is to physiologically
reduce zinc ectopeptidases, which deactivate enkephalins, hence boosting the actions of
enkephalins.
2. What is the biochemical nature of opiorphin, where was it isolated, and what is its mechanism
of action?
Opiorphin is a pentapeptide with the amino acid sequence QRFSR. It is an inhibitor of neutral
ectoendopeptidase and ecto-aminopeptidase enzymes.Human saliva is where it was initially
discovered.Opiorphin lessens the breakdown of enkephalins, which are naturally occurring
opioids. As a result, more enkephalins are available to attach to opioid receptors and provide
analgesic effects.
3. How were the anti-nociceptive actions of opinorphin evaluated in the Popik study?
The tail-flick test in mice was used in the Popik study to assess the pain-relieving effects of
opiorphin. This test determines how long it takes a mouse to remove its tail from a radiant heat
source.The researchers measured the mice's tail-flick latency at different periods following
injection after giving them opiorphin. The findings indicated that opiorphin dramatically
prolonged tail-flick latency, proving its analgesic effect.
4. What was the purpose of the naloxone that was used in some of the tail flick experiments?
Naloxone counteracts the effects of opioids by acting as an opioid receptor antagonist.To see if
opioid receptors were involved in the antinociceptive effects of opiorphin, naloxone was utilized
in the tail-flick studies. The implication would be that opiorphin was actually acting via opioid
receptors if naloxone suppressed its effects.
5. What other potentially useful behavioral effect was observed from the use of opiorphin on
mice? How was this determined?
In addition to its pain-relieving properties, the study also found that opiorphin had an
antidepressant-like impact on mice. The forced swim test, a behavioral experiment that gauges
how long a mouse stays motionless when submerged in a container of water, was used to ascertain
this impact. Mice given opiorphin exhibited considerably less immobility than control mice,
