Co-administration of opioids and cannabinoids can enhance pain relief even when administered on different days. Repeated systemic administration of morphine has been shown to enhance the antinociceptive effect of tetrahydrocannabinol (THC) administered 12h later, and repeated microinjection of the cannabinoid receptor agonist HU-210 into the ventrolateral periaqueductal gray (PAG) has been shown to enhance the antinociceptive effect of morphine administered 1 day later. The primary objective of the present study was to test the hypothesis that this cannabinoid/opioid interaction is bidirectional. Experiment 1 showed that microinjection of morphine into the ventrolateral PAG of male Sprague-Dawley rats twice daily for 2 days enhanced the antinociceptive effect of HU-210 measured 1 day later. In Experiment 2, twice daily systemic injections of THC enhanced the antinociceptive effect of morphine administered 1 day later. These results complement the previously mentioned studies by showing that morphine and cannabinoid interactions are bidirectional and that the ventrolateral PAG plays an important role in this effect. In contrast to the PAG, repeated administration of HU-210 or the cannabinoid receptor agonist, WIN 55,212-2, into the RVM had a neurotoxic effect. Rats became ill following repeated cannabinoid administration whether given alone or with morphine. Presumably, this neurotoxic effect was caused by the high cannabinoid concentration following RVM microinjection because rats did not become ill following repeated systemic THC administration. These findings indicate that alternating opioid and cannabinoid treatment could produce a longer lasting and more potent analgesia than either compound given alone.
Pharmacology, Toxicology and Pharmaceutical Science
5
9%
Psychology
5
9%
Other
9
16%
Unknown
15
27%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 4. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 07 March 2023.
All research outputs
#11,627,647
of 34,763,505 outputs
Outputs from Pharmacology, Biochemistry & Behavior
#1,486
of 4,299 outputs
Outputs of similar age
#81,221
of 230,451 outputs
Outputs of similar age from Pharmacology, Biochemistry & Behavior
#11
of 30 outputs
Altmetric has tracked 34,763,505 research outputs across all sources so far. This one has received more attention than most of these and is in the 65th percentile.
So far Altmetric has tracked 4,299 research outputs from this source. They typically receive a little more attention than average, with a mean Attention Score of 6.7. This one has gotten more attention than average, scoring higher than 64% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 230,451 tracked outputs that were published within six weeks on either side of this one in any source. This one has gotten more attention than average, scoring higher than 62% of its contemporaries.
We're also able to compare this research output to 30 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 60% of its contemporaries.
