Effect of steady-state methadone on high fructose corn syrup consumption in rats

Integration of Endogenous Opioid System Research in the Interprofessional Diagnosis and Treatment of Obesity and Eating Disorders

This third and final chapter in our trilogy introduces the clinical distinctions and phenotypical similarities between obesity and eating disorders. Research elaborating on the shared neurobiological substrates for obesity and eating disorders is discussed. We present an interprofessional model of treatment for both disordered eating and for obesity. Additionally, this chapter establishes the translational importance of research connecting endogenous opioid activity with both obesity and eating disorders, with an emphasis on clinical interventions. We conclude with a discussion of future directions for research.

Metabolic profiles associated with opioid use and opioid use disorder: a narrative review of the literature

Purpose of Review

Opioid use disorder (OUD) is a chronic, relapsing condition that is epidemic in the USA. OUD is associated with serious adverse consequences, including higher incarceration rates, impaired medical and mental health, and overdose-related fatalities. Several medications with demonstrated clinical efficacy in reducing opioid use are approved to treat OUD. However, there is evidence that medications for OUD cause metabolic impairments, which raises concerns over the long-term metabolic health of individuals recovering from OUD. Here, we summarize the scientific literature on the metabolic effects of the use of opioids, including medications for treating OUD.

Recent Findings

Our findings showed lower body weight and adiposity, and better lipid profiles in individuals with OUD. In individuals with diabetes mellitus, opioid use was associated with lower blood glucose levels. In contrast, among individuals without underlying metabolic conditions, opioids promoted insulin resistance. Treatment of OUD patients with the agonists methadone or buprenorphine caused weight gain, increased liking and intake of sugar, and impaired lipid profile and glucose metabolism, whereas treatment with the antagonist naltrexone demonstrated evidence for reduced sweet preferences.

Summary

Our findings highlighted a gap in knowledge regarding the safety of medications for OUD. Further research is needed to determine how best to reduce the risk of metabolic disorder in the treatment of OUD with opioid agonists versus antagonists.

Sucrose subjective response and eating behaviors among individuals with opioid use disorder

BACKGROUND

While opioid agonists represent the most efficacious treatment for opioid use disorder (OUD), they may enhance the reinforcing effects of sweets, placing individuals at risk for weight gain and associated consequences. We examined sucrose subjective response among adults receiving opioid agonist treatment vs. a comparison sample without OUD.

METHODS

Forty adults with (OUD+) and 40 without OUD (OUD-) completed an intake battery of eating behaviors and body mass index. During two same-day sessions, participants sampled six experimenter-administered sucrose solutions (0, 0.10, 0.25, 0.50, 0.75, 1.0 M), each three times, under double-blind conditions and rated the pleasantness and intensity of each.

RESULTS

OUD + participants presented with a higher prevalence of obesity and unhealthy eating behaviors vs. OUD- participants (p's < 0.05). They rated sucrose solutions as less pleasant than OUD- participants (p < 0.001), though this effect was limited to the three lowest concentrations (0, 0.10, 0.25M). There were no group differences on intensity ratings (p = 0.35). A change from baseline (placebo) analysis indicated a higher magnitude of change in pleasantness ratings and a lower magnitude of change in intensity ratings from 0M in OUD+ vs. OUD- (p's < 0.05).

CONCLUSIONS

OUD+ participants exhibited a higher magnitude of change in pleasantness ratings from placebo vs. OUD-, which was largely driven by pronounced differences in perceived pleasantness of essentially unsweet solutions. OUD+ participants presented with a consistently more severe profile in regard to eating behaviors. These data highlight the risk factors experienced by OUD+ individuals that extend beyond drug-related risks and may inform future efforts to improve health outcomes.

Associations between opioid dependence and sweet taste preference

RATIONALE

Past research suggests that people with opioid dependence show increased consumption of sweet food, but it is unclear if this is influenced by altered taste preference and/or taste perception.

OBJECTIVES

We tested whether people prescribed opioid substitution therapy (OST) exhibited a shift in preference towards sweeter flavours, and altered perception of sweetness, and explored whether these measures of taste preference/perception were associated with measures of opioid use.

METHODS

Three groups of participants (people prescribed OST, n=36; people with past opioid dependence, but now abstinent from all opioids, n=18; and controls with no history of substance dependence other than nicotine, n=29) provided ratings of "sweetness", "liking", and "desire" of 4 solutions with varying concentrations of sucrose.

RESULTS

We did not find significant differences between groups in the effect of sucrose concentration on "sweetness", "liking", or "desire" ratings. However, among those prescribed OST, frequency of recent illicit opioid use was associated with reduced perception of "sweetness" of low sucrose concentrations. Higher methadone dose was associated with a shift towards liking sweeter concentrations. Among those with past opioid dependence, longer duration of abstinence from opioids was associated with a shift towards liking sweeter concentrations.

CONCLUSIONS

Among people currently dependent on opioids, reduced sensitivity to low levels of sweetness and increased preference for sweeter flavours may be associated with increased dependence on opioids. Among those who have ceased opioid use, the association between preference for sweeter flavours and duration of abstinence is a novel finding that deserves further investigation.

Evidence of hypoglycemic anhedonia and modulation by bupropion in rats

BACKGROUND

Disorders characterized by dysfunction of glucose metabolism are often comorbid with depression. The current study investigated whether a hypoglycemic state caused by 2-deoxy-d-glucose (2-DG) can result in anhedonic behaviors responsive to stimulation of monoamine activity.

METHODS

In experiment 1, male Sprague-Dawley rats were tested for maintenance of intra-oral self-administration (IOSA) of a sweet solution after pre-treatment with 300 or 500 mg/kg 2-DG, a blocker of glucose metabolism. Experiment 2 determined whether exposure to an environment previously paired with the effects of 2-DG (0, 200 or 300 mg/kg) can influence IOSA, and whether 2-DG can modify taste reactivity to same sweet solution. Finally, experiment 3 examined whether 0 or 30 mg/kg bupropion, a monoamine-reuptake blocker, would attenuate the effect of 300 mg/kg 2-DG on IOSA and taste reactivity.

RESULTS

It was found that 2-DG produced a sustained decrease in IOSA when animals were tested drug-free. This decrease in IOSA did not appear linked to place conditioning or to alterations in taste reactivity, and it was partially normalized by pre-treatment with bupropion.

CONCLUSIONS

Taken together, these results in rats suggest that rapid hypoglycemia can induce an anhedonic state characterized by impaired consummatory responses to nutritional incentive stimuli and that can be alleviated by the antidepressant bupropion.

Metabolic and Addiction Indices in Patients on Opioid Agonist Medication-Assisted Treatment: A Comparison of Buprenorphine and Methadone

Metabolic hormones stabilize brain reward and motivational circuits, whereas excessive opioid consumption counteracts this effect and may impair metabolic function. Here we addressed the role of metabolic processes in the course of the agonist medication-assisted treatment for opioid use disorder (OUD) with buprenorphine or methadone. Plasma lipids, hemoglobin A1C, body composition, the oral glucose tolerance test (oGTT) and the Sweet Taste Test (STT) were measured in buprenorphine- (n = 26) or methadone (n = 32)- treated subjects with OUD. On the whole, the subjects in both groups were overweight or obese and insulin resistant; they displayed similar oGTT and STT performance. As compared to methadone-treated subjects, those on buprenorphine had significantly lower rates of metabolic syndrome (MetS) along with better values of the high-density lipoproteins (HDL). Subjects with- vs. without MetS tended to have greater addiction severity. Correlative analyses revealed that more buprenorphine exposure duration was associated with better HDL and opioid craving values. In contrast, more methadone exposure duration was associated with worse triglycerides-, HDL-, blood pressure-, fasting glucose- and hemoglobin A1C values. Buprenorphine appears to produce beneficial HDL- and craving effects and, contrary to methadone, its role in the metabolic derangements is not obvious. Our data call for further research aimed at understanding the distinctive features of buprenorphine metabolic effects vis-à-vis those of methadone and their potential role in these drugs' unique therapeutic profiles.