Reduced Endocannabinoid Tone in Saliva of Chronic Orofacial Pain Patients

Hair and Saliva Endocannabinoid and Steroid Hormone Analysis by Liquid Chromatography Paired with Tandem Mass Spectrometry

Endocannabinoids are lipid neurotransmitters that play an important part in human health. Recent methods have found that quantification of endocannabinoids in hair and saliva samples is possible using liquid chromatography paired with tandem mass spectrometry (LC-MS/MS). This chapter describes two simple sample preparation methods that can be used to prepare hair and saliva samples for analysis using LC-MS/MS. Our LC-MS/MS method can be applied to both hair and saliva samples and is sufficiently sensitive for endocannabinoid, as well as steroid hormone, quantification in both of these sample matrices. This chapter provides a comprehensive description of how this can be achieved and provides tips and tricks for troubleshooting problems users may experience.

Excessive alcohol intake produces persistent mechanical allodynia and dysregulates the endocannabinoid system in the lumbar dorsal root ganglia of genetically-selected Marchigian Sardinian alcohol-preferring rats

Epidemiological data indicate a strong association between alcohol use disorder (AUD) and neuropathic pain. Genetically-selected Marchigian Sardinian alcohol-preferring (msP) rats exhibit a high preference for alcohol compared with their background strain (Wistar rats), but their sensitivity to mechanical allodynia after chronic alcohol exposure is unknown. The present study compared the development of mechanical allodynia between "low, non-pathological drinker" Wistar rats and "high drinker" msP rats using the two-bottle choice (2BC) free-access procedure. Several studies reported the involvement of endocannabinoids (eCBs) in modulating mechanical allodynia, but there are no data on their role in alcohol-related allodynia. Thus, the present study assessed eCBs and their related lipid species in lumbar dorsal root ganglia (DRG) and correlated them with mechanical allodynia in our model. We found that male and female msP rats developed persistent mechanical allodynia during protracted abstinence from alcohol, presenting no sign of recovery, as opposed to Wistar rats. This effect directly correlated with their total alcohol intake. Notably, we found a correlation between lower lumbar DRG 2-arachidonoylglycerol (2-AG) levels and the development of higher mechanical allodynia during abstinence in msP rats of both sexes but not in Wistar rats. Moreover, alcohol-exposed and abstinent msP and Wistar females but not males exhibited significant alterations of thromboxane B2 and prostaglandin E2/prostaglandin D2 compared with naive rats. These findings demonstrate that DRG 2-AG metabolism is altered in msP rats during prolonged abstinence and represents a potentially interesting pharmacological target for the treatment of mechanical allodynia during alcohol abstinence.

Advances in targeted liquid chromatography-tandem mass spectrometry methods for endocannabinoid and N-acylethanolamine quantification in biological matrices: A systematic review

Liquid chromatography paired with tandem mass spectrometry (LC-MS/MS) is the gold standard in measurement of endocannabinoid concentrations in biomatrices. We conducted a systematic review of literature to identify advances in targeted LC-MS/MS methods in the period 2017-2024. We found that LC-MS/MS methods for endocannabinoid quantification are relatively consistent both across time and across biomatrices. Recent advances have primarily been in three areas: (1) sample preparation techniques, specific to the chosen biomatrix; (2) the range of biomatrices tested, recently favoring blood matrices; and (3) the breadth of endocannabinoid and endocannabinoid-like analytes incorporated into assays. This review provides a summary of the recent literature and a guide for researchers looking to establish the best methods for quantifying endocannabinoids in a range of biomatrices.

Sex-dimorphism in human serum endocannabinoid and n-acyl ethanolamine concentrations across the lifespan

The endocannabinoid (ECB) system has recently been considered a potential treatment target for various clinical disorders. However, research around age- and sex-related changes within the ECB system is relatively limited. To improve our understanding of these changes, the current study measured arachidonoyl ethanolamide (AEA), 2-arachidonoyl glycerol (2-AG), oleoylethanolamine (OEA), palmitoylethanolamine (PEA), arachidonic acid (AA), cortisol, and progesterone in pooled serum samples stratified by sex (male and female) and age groups (5-15; 15-30; 30-45; 45-60; 60-75; 85+), using liquid-chromatography tandem mass spectrometry. Serum progesterone levels significantly increased in females of the 15-30 and 30-45 age groups, before declining. Significantly higher cortisol, AEA, 2-AG, OEA, and PEA were found in males and in older age, while significantly higher AA was found in females. Our results indicate that ECBs and related hormones exhibit sexual dimorphism in the age ranges that correspond with female pregnancy, menopause, and post menopause. Male testosterone levels most likely influences male ECB changes throughout the lifespan. Future research could capitalise on these findings by performing repeated measurements in individuals in a longitudinal style, to further refine the temporal profile of age-specific changes to the ECB system identified here.

Salivary Endocannabinoid Profiles in Chronic Orofacial Pain and Headache Disorders: An Observational Study Using a Novel Tool for Diagnosis and Management

The endocannabinoid system is involved in physiological and pathological processes, including pain generation, modulation, and sensation. Its role in certain types of chronic orofacial pain (OFP) has not been thoroughly examined. By exploring the profiles of specific salivary endocannabinoids (eCBs) in individuals with different types of OFP, we evaluated their use as biomarkers and the influence of clinical parameters and pain characteristics on eCB levels. The salivary levels of anandamide (AEA), 2-arachidonoyl glycerol (2-AG), and their endogenous breakdown product arachidonic acid (AA), as well as the eCB-like molecules N-palmitoylethanolamide (PEA) and N-oleoylethanolamide (OEA), were assessed in 83 OFP patients and 43 pain-free controls using liquid chromatography/tandem mass spectrometry. Patients were grouped by diagnosis: post-traumatic neuropathy (PTN), trigeminal neuralgia (TN), temporomandibular disorder (TMD), migraine, tension-type headache (TTH), and burning mouth syndrome (BMS). Correlation analyses between a specific diagnosis, pain characteristics, and eCB levels were conducted. Significantly lower levels of 2-AG were found in the TN and TTH groups, while significantly lower PEA levels were found in the migraine group. BMS was the only group with elevated eCBs (AEA) versus the control. Significant correlations were found between levels of specific eCBs and gender, health-related quality of life (HRQoL), BMI, pain duration, and sleep awakenings. In conclusion, salivary samples exhibited signature eCBs profiles for major OFP disorders, especially migraine, TTH, TN, and BMS. This finding may pave the way for using salivary eCBs biomarkers for more accurate diagnoses and management of chronic OFP patients.