Acute Delta 9-tetrahydrocannabinol administration differentially alters the hippocampal opioid system in adult female and male rats

Evaluation of pre-hospital cannabis exposure and hospital opioid utilization in a trauma population: A retrospective cohort

PURPOSE

Cannabis utilization has increased over time for recreational and medical purposes due to its legalization or decriminalization. The effects of cannabis use on opioid utilization are not well understood. The primary objective was to evaluate the total opioid utilization, measured in morphine milligram equivalents (MME), in hospitalized trauma patients that tested positive for tetrahydrocannabinol (THC) on a urine drug screen (UDS).

METHODS

This was a retrospective, cohort study in a level 1 trauma center between 10/17/17 and 12/31/19. Adult trauma patients (aged 15 years and older) who had a UDS completed within 48 h of hospital arrival were eligible for inclusion. Patients were excluded for a hospitalization >14 days, death within 24 h, severe alcohol withdrawal, prescribed cannabinoids, high daily opioid use prior-to-arrival, or transitioned to hospice or palliative care. Group assignments were determined based on the presence or absence of THC on the UDS.

RESULTS

The analysis included 750 patients with 160 (21 %) THC positive patients. The population were primarily male (64.6 %), median age of 56 years [IQR 35-72], with blunt (93 %) injuries from motor vehicle crash or falls (79 %). The THC group was more likely to have other substances present, including amphetamines, benzodiazepines, opiates, and cocaine. The THC group had a higher median injury severity score (10 [IQR 5-17] vs. 9 [5-14], p = 0.0056), and maximum abbreviated injury score (3 [IQR 2-3] vs. 2 [IQR 2-3], p = 0.0009). The THC group had a total higher median opioid utilization during the hospitalization (155 [IQR 68-367] vs. 62 [IQR 13-175] MME; p < 0.0001), which included higher opioid use in the emergency department, floor, and intensive care unit. There were no significant differences in secondary outcomes except the THC group was more likely to receive an opioid prescription at discharge and more likely to require mechanical ventilation. Based on multivariable regression analyses, other variables were associated with increased opioid utilization.

CONCLUSION

Pre-existing THC exposure may be associated with an increased hospital opioid utilization in a trauma population. However, other variables may also play a role in opioid utilization.

Sex differences in the rodent hippocampal opioid system following stress and oxycodone associated learning processes

Over the past two decades, opioid abuse has risen especially among women. In both sexes hippocampal neural circuits involved in associative memory formation and encoding of motivational incentives are critically important in the transition from initial drug use to drug abuse/dependence. Opioid circuits, particularly the mossy fiber pathway, are crucial for associative memory processes important for addiction. Our anatomical studies, especially those utilizing electron microscopic immunocytochemistry, have provided unique insight into sex differences in the distribution of opioid peptides and receptors in specific hippocampal circuits and how these distributions are altered following stress and oxycodone-associative learning processes. Here we review the hippocampal opioid system in rodents with respect to ovarian hormones effects and baseline sex differences then sex differences following acute and chronic stress. Next, we review sex differences in the hippocampal opioid system in unstressed and chronically stressed rats following oxycodone conditioned place preference. We show that opioid peptides and receptors are distributed within hippocampal circuits in females with elevated estrogen states in a manner that would enhance sensitivity to endogenous and exogenous opioids. Moreover, chronic stress primes the opioid system in females in a manner that would promote opioid-associative learning processes. In contrast, chronic stress has limited effects on the opioid system in males and reduces its capacity to support opioid-mediated learning processes. Interestingly, acute stress appears to prime males for opioid associative learning. On a broader scale the findings highlighted in this review have important implications in understanding sex differences in opioid drug use and abuse.