Spontaneous and Naloxone-Precipitated Withdrawal Behaviors From Chronic Opiates are Accompanied by Changes in N-Oleoylglycine and N-Oleoylalanine Levels in the Brain and Ameliorated by Treatment With These Mediators

Abstract

Rationale: The endocannabinoidome mediators, N-Oleoylglycine (OlGly) and N-Oleoylalanine (OlAla), have been shown to reduce acute naloxone-precipitated morphine withdrawal affective and somatic responses.Objectives: To determine the role and mechanism of action of OlGly and OlAla in withdrawal responses from chronic exposure to opiates in male Sprague-Dawley rats.Methods: Opiate withdrawal was produced: 1) spontaneously 24 h following chronic exposure to escalating doses of morphine over 14 days (Experiments 1 and 2) and steady-state exposure to heroin by minipumps for 12 days (Experiment 3), 2) by naloxone injection during steady-state heroin exposure (Experiment 4), 3) by naloxone injection during operant heroin self-administration (Experiment 5).Results: In Experiment 1, spontaneous morphine withdrawal produced somatic withdrawal reactions. The behavioral withdrawal reactions were accompanied by suppressed endogenous levels of OlGly in the nucleus accumbens, amygdala, and prefrontal cortex, N-Arachidonylglycerol and OlAla in the amygdala, 2-arachidonoylglycerol in the nucleus accumbens, amygdala and interoceptive insular cortex, and by changes in colonic microbiota composition. In Experiment 2, treatment with OlAla, but not OlGly, reduced spontaneous morphine withdrawal responses. In Experiment 3, OlAla attenuated spontaneous steady-state heroin withdrawal responses at both 5 and 20 mg/kg; OlGly only reduced withdrawal responses at the higher dose of 20 mg/kg. Experiment 4 demonstrated that naloxone-precipitated heroin withdrawal from steady-state exposure to heroin (7 mg/kg/day for 12 days) is accompanied by tissue-specific changes in brain or gut endocannabinoidome mediator, including OlGly and OlAla, levels and colonic microbiota composition, and that OlAla (5 mg/kg) attenuated behavioural withdrawal reactions, while also reversing some of the changes in brain and gut endocannabinoidome and gut microbiota induced by naloxone. Experiment 5 demonstrated that although OlAla (5 mg/kg) did not interfere with operant heroin self-administration on its own, it blocked naloxone-precipitated elevation of heroin self-administration behavior.Conclusion: These results suggest that OlAla and OlGly are two endogenous mediators whose brain concentrations respond to chronic opiate treatment and withdrawal concomitantly with changes in colon microbiota composition, and that OlAla may be more effective than OlGly in suppressing chronic opiate withdrawal responses.

High‐performance liquid chromatography‐tandem mass spectrometry method for the analysis of N‐oleoyl glycine and N‐oleoyl alanine in brain and plasma

“…The presence of this suspected isobaric compound in the brain, without chromatographic resolution, raises the possibility of overreporting OlAla concentrations in the brain. A study measuring OlGly and OlAla levels in the amygdala, prefrontal cortex, nucleus accumbens, insular cortex, colon, and jejunum from male Sprague-Dawley rats failed to detect OlAla in brain 50 min after exogenous administration, but OlAla was detected in the colon with levels increasing after exogenous administration [31]. Another study stating that brain levels of OlAla increased following administration in mice did not show the data or include the methodological parameters for specifically analyzing OlAla [15].…”

“…Additionally, without separation, interferences may occur from other isobaric lipids and compounds, which limit the specificity and accuracy of quantitation. While other methods include OlGly and OlAla in small panels containing related lipids and endocannabinoids [3,5,12,15,16,31], these methods lacked validation parameters for OlGly and OlAla including validation of a substitute matrix for these endogenous lipids, linearity, matrix effects, autosampler stability. Of the published methods including OlGly and OlAla, only two report recovery for arachidonoyl glycine-d 8 (AraGly-d 8 ), which has been used as an internal standard (ISTD) as presently,no deuterated ISTDs for OlGly or OlAla are commercially available.…”

(Wh)olistic (E)ndocannabinoidome-Microbiome-Axis Modulation through (N)utrition (WHEN) to Curb Obesity and Related Disorders

“…In a context different from obesity and dysmetabolism, also NAAs have recently been suggested to produce some of their pharmacological effects by modifying the gut microbiota. A recent study [ 233 ] showed that chronic morphine or heroin withdrawal in rats could change NOleG and NOleA levels in the brain and/or the gut. These two compounds, and particularly NOleA, when administered exogenously, reduce some signs of spontaneous morphine withdrawal and naloxone-precipitated withdrawal, and this latter effect of NOleA was also accompanied by the reversal of some withdrawal-induced gut microbiota changes.…”

Orally Administered N-Oleoyl Alanine Blocks Acute Opioid Withdrawal Induced-Conditioned Place Preference and Attenuates Somatic Withdrawal following Chronic Opioid Exposure in Rats

“…Within the N-acyl amino acid family, both N-Oleoyl glycine (OlGly) and N-Oleoyl alanine (OlAla) have been shown to participate in the behavioral and neurochemical responses produced by withdrawal from opioids in preclinical animal models [12,[14][15][16]. Acute morphine withdrawal (MWD) is readily modelled in rodents by exposure to a high-dose of morphine followed 24-h later by administration of the mu-opioid receptor antagonist naloxone.…”