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Core Topics => Drugs => Opiates & Opioids => Topic started by: Chip on July 02, 2019, 04:06:41 PM
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source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3623050/
Some more on endorphins/morphine and my studies on drugs and the mechanism of memory and tissue ... because you can learn a lot from (being) a junky :P ;) :)
some excerpts:
Dual effect of morphine in long-term social memory in rat
April 2013
Abstract
Background and Purpose
Bimodal dose–response relationships have been demonstrated in animals and humans following morphine administration. We examined if systemic administration of morphine, in extremely low (μg) and high (mg, analgesic) doses, changed the learning process.
Experimental Approach
In the social learning test, an adult rat investigates a juvenile. The juvenile is submitted to a second encounter after a few days and investigation by the adult should be reduced. Morphine was administered before the first encounter between rats, and the critical test was performed 24, 72 or 168 h later, when animals were re-exposed to each other, in the absence of morphine.
Social memory assessment
Social memory test is based on the propensity of an adult rodent to inspect an unknown juvenile rodent. In this paradigm (Dantzer et al., 1987), two rats (one adult and one juvenile) are exposed to each other for a short time (2 min), and the time that the adult explores the juvenile is measured.
Then rats are re-exposed 24, 72 or 168 h after (second exposure). Re-exposing the rat also to an unfamiliar juvenile was used as control.
The effect on social memory retrieval of morphine at different doses was tested by a two-factor repeated-measures analysis using a mixed linear model.
The considered factors are morphine dose (between group factor), trial (repeated factor, initial versus trial) or familiar versus unfamiliar juvenile (trial versus trial) and the interaction between these two factors.
The same model was used to test the interval and trial effect on social memory with and without morphine administration except that, in this case, the considered factor are the exposure interval (the between group factor) and trial (initial versus trial) or familiar versus unfamiliar juvenile (trial versus trial).
Key Results
Low doses of morphine, comparable with endogenous brain concentrations, enhanced long-term memory recognition; while high doses did the reverse, indicating the adult failed to recognize the juvenile.
Recognition of a familiar rat appeared to be mediated within the brain accessory olfactory bulb (AOB) by an opioid system intrinsic to the olfactoryWiki system through μ-opioid receptorsWiki (MORs).
At this supraspinal site, the PLC/PKC signalling pathway was activated by extremely low morphine doses.
Conclusions and Implications
Morphine treatment administration may either disrupt or facilitate social memory, depending on the dose, extending to memory formation the bimodal effects of morphine previously shown in pain.
Social memory formation elicited by extremely low morphine doses, was mediated within the AOB by an opioid system, intrinsic to the olfactory system through MORs.
read the full article at the source link ...