Impact of inpatient addiction psychiatry consultation on opioid use disorder outcomes.

BACKGROUND AND OBJECTIVES: Addiction consultation services provide access to specialty addiction care during general hospital admission. This study assessed opioid use disorder (OUD) outcomes associated with addiction consultation. METHODS: Retrospective cohort study of individuals with OUD admitted to an academic medical center between 2018 and 2023. The exposure was addiction consultation. Outcomes included initiating medication for OUD (MOUD), hospital length of stay, before-medically-advised (BMA) discharge, and 30- and 90-day postdischarge acute care utilization. RESULTS: Of 26,766 admissions (10,501 patients) with OUD, 2826 addiction consultations were completed. Consultation cohort was more likely to be young, male, and White than controls. Consultation was associated with greater MOUD initiation (adjusted odds ratio [aOR], 5.07; 95% confidence interval [CI], 4.41-5.82), fewer emergency department visits at 30 (aOR, 0.78; 95% CI, 0.67-0.92) and 90 (aOR, 0.79; 95% CI, 0.69-0.89) days, and fewer hospitalizations at 30 (aOR, 0.65; 95% CI, 0.56 to 0.76) and 90 (aOR, 0.67; 95% CI, 0.59-0.76) days. Additionally, consultation patients were more likely to have a longer hospital stay and leave BMA. CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: Addiction consultation was associated with increased MOUD initiation and reduced postdischarge acute care utilization. This is the largest study to date showing a significant association between addiction psychiatry consultation and improved OUD outcomes when compared to controls. The observed reduction in postdischarge acute care utilization remains even after adjusting for MOUD initiation. Disparities in access to addiction consultation warrant further study.

Effect of a Co-Located Bridging Recovery Initiative on Hospital Length of Stay Among Patients With Opioid Use Disorder: The BRIDGE Randomized Clinical Trial.

Importance: Co-located bridge clinics aim to facilitate a timely transition to outpatient care for inpatients with opioid use disorder (OUD); however, their effect on hospital length of stay (LOS) and postdischarge outcomes remains unclear. Objective: To evaluate the effect of a co-located bridge clinic on hospital LOS among inpatients with OUD. Design, Setting, and Participants: This parallel-group randomized clinical trial recruited 335 adult inpatients with OUD seen by an addiction consultation service and without an existing outpatient clinician to provide medication for OUD (MOUD) between November 25, 2019, and September 28, 2021, at a tertiary care hospital affiliated with a large academic medical center and its bridge clinic. Intervention: The bridge clinic included enhanced case management before and after hospital discharge, MOUD prescription, and referral to a co-located bridge clinic. Usual care included MOUD prescription and referrals to community health care professionals who provided MOUD. Main Outcomes and Measures: The primary outcome was the index admission LOS. Secondary outcomes, assessed at 16 weeks, were linkage to health care professionals who provided MOUD, MOUD refills, same-center emergency department (ED) and hospital use, recurrent opioid use, quality of life (measured by the Schwartz Outcome Scale-10), overdose, mortality, and cost. Analysis was performed on an intent-to-treat basis. Results: Of 335 participants recruited (167 randomized to the bridge clinic and 168 to usual care), the median age was 38.0 years (IQR, 31.9-45.7 years), and 194 (57.9%) were male. The median LOS did not differ between arms (adjusted odds ratio [AOR], 0.94 [95% CI, 0.65-1.37]; P = .74). At the 16-week follow-up, participants referred to the bridge clinic had fewer hospital-free days (AOR, 0.54 [95% CI, 0.32-0.92]), more readmissions (AOR, 2.17 [95% CI, 1.25-3.76]), and higher care costs (AOR, 2.25 [95% CI, 1.51-3.35]), with no differences in ED visits (AOR, 1.15 [95% CI, 0.68-1.94]) or deaths (AOR, 0.48 [95% CI, 0.08-2.72]) compared with those receiving usual care. Follow-up calls were completed for 88 participants (26.3%). Participants referred to the bridge clinic were more likely to receive linkage to health care professionals who provided MOUD (AOR, 2.37 [95% CI, 1.32-4.26]) and have more MOUD refills (AOR, 6.17 [95% CI, 3.69-10.30]) and less likely to experience an overdose (AOR, 0.11 [95% CI, 0.03-0.41]). Conclusions and Relevance: This randomized clinical trial found that among inpatients with OUD, bridge clinic referrals did not improve hospital LOS. Referrals may improve outpatient metrics but with higher resource use and expenditure. Bending the cost curve may require broader community and regional partnerships. Trial Registration: ClinicalTrials.gov Identifier: NCT04084392.

Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of Raptor and this contributes to the weight loss effect of liraglutide.

The canonical target of the glucagon-like peptide-1 receptor (GLP-1R), Protein Kinase A (PKA), has been shown to stimulate mechanistic Target of Rapamycin Complex 1 (mTORC1) by phosphorylating the mTOR-regulating protein Raptor at Ser791 following ß-adrenergic stimulation. The objective of these studies is to test whether GLP-1R agonists similarly stimulate mTORC1 via PKA phosphorylation of Raptor at Ser791 and whether this contributes to the weight loss effect of the therapeutic GLP-1R agonist liraglutide. We measured phosphorylation of the mTORC1 signaling target ribosomal protein S6 in Chinese Hamster Ovary cells expressing GLP-1R (CHO-Glp1r) treated with liraglutide in combination with PKA inhibitors. We also assessed liraglutide-mediated phosphorylation of the PKA substrate RRXS*/T* motif in CHO-Glp1r cells expressing Myc-tagged wild-type (WT) Raptor or a PKA-resistant (Ser791Ala) Raptor mutant. Finally, we measured the body weight response to liraglutide in WT mice and mice with a targeted knock-in of PKA-resistant Ser791Ala Raptor. Liraglutide increased phosphorylation of S6 and the PKA motif in WT Raptor in a PKA-dependent manner but failed to stimulate phosphorylation of the PKA motif in Ser791Ala Raptor in CHO-Glp1r cells. Lean Ser791Ala Raptor knock-in mice were resistant to liraglutide-induced weight loss but not setmelanotide-induced (melanocortin-4 receptor-dependent) weight loss. Diet-induced obese Ser791Ala Raptor knock-in mice were not resistant to liraglutide-induced weight loss; however, there was weight-dependent variation such that there was a tendency for obese Ser791Ala Raptor knock-in mice of lower relative body weight to be resistant to liraglutide-induced weight loss compared to weight-matched controls. Together, these findings suggest that PKA-mediated phosphorylation of Raptor at Ser791 contributes to liraglutide-induced weight loss.

Fibroblast growth factor-21 is required for weight loss induced by the glucagon-like peptide-1 receptor agonist liraglutide in male mice fed high carbohydrate diets.

OBJECTIVE: Glucagon-like peptide-1 receptor (GLP-1R) agonists (GLP-1RA) and fibroblast growth factor-21 (FGF21) confer similar metabolic benefits. GLP-1RA induce FGF21, leading us to investigate mechanisms engaged by the GLP-1RA liraglutide to increase FGF21 levels and the metabolic relevance of liraglutide-induced FGF21. METHODS: Circulating FGF21 levels were measured in fasted male C57BL/6J, neuronal GLP-1R knockout, ß-cell GLP-1R knockout, and liver peroxisome proliferator-activated receptor alpha knockout mice treated acutely with liraglutide. To test the metabolic relevance of liver FGF21 in response to liraglutide, chow-fed control and liver Fgf21 knockout (LivFgf21-/-) mice were treated with vehicle or liraglutide in metabolic chambers. Body weight and composition, food intake, and energy expenditure were measured. Since FGF21 reduces carbohydrate intake, we measured body weight in mice fed matched diets with low- (LC) or high-carbohydrate (HC) content and in mice fed a high-fat, high-sugar (HFHS) diet. This was done in control and LivFgf21-/- mice and in mice lacking neuronal ß-klotho (Klb) expression to disrupt brain FGF21 signaling. RESULTS: Liraglutide increases FGF21 levels independently of decreased food intake via neuronal GLP-1R activation. Lack of liver Fgf21 expression confers resistance to liraglutide-induced weight loss due to attenuated reduction of food intake in chow-fed mice. Liraglutide-induced weight loss was impaired in LivFgf21-/- mice when fed HC and HFHS diets but not when fed a LC diet. Loss of neuronal Klb also attenuated liraglutide-induced weight loss in mice fed HC or HFHS diets. CONCLUSIONS: Our findings support a novel role for a GLP-1R-FGF21 axis in regulating body weight in a dietary carbohydrate-dependent manner.

Liver Fibroblast Growth Factor 21 (FGF21) is Required for the Full Anorectic Effect of the Glucagon-Like Peptide-1 Receptor Agonist Liraglutide in Male Mice fed High Carbohydrate Diets.

Glucagon-like peptide-1 receptor (GLP-1R) agonists and fibroblast growth factor 21 (FGF21) confer similar metabolic benefits. Studies report that GLP-1RA induce FGF21. Here, we investigated the mechanisms engaged by the GLP-1R agonist liraglutide to increase FGF21 levels and the metabolic relevance of liraglutide-induced FGF21. We show that liraglutide increases FGF21 levels via neuronal GLP-1R activation. We also demonstrate that lack of liver Fgf21 expression confers partial resistance to liraglutide-induced weight loss. Since FGF21 reduces carbohydrate intake, we tested whether the contribution of FGF21 to liraglutide-induced weight loss is dependent on dietary carbohydrate content. In control and liver Fgf21 knockout (Liv Fgf21 -/- ) mice fed calorically matched diets with low- (LC) or high-carbohydrate (HC) content, we found that only HC-fed Liv Fgf21 -/- mice were resistant to liraglutide-induced weight loss. Similarly, liraglutide-induced weight loss was partially impaired in Liv Fgf21 -/- mice fed a high-fat, high-sugar (HFHS) diet. Lastly, we show that loss of neuronal ß-klotho expression also diminishes liraglutide-induced weight loss in mice fed a HC or HFHS diet, indicating that FGF21 mediates liraglutide-induced weight loss via neuronal FGF21 action. Our findings support a novel role for a GLP-1R-FGF21 axis in regulating body weight in the presence of high dietary carbohydrate content.

High fat diet blunts stress-induced hypophagia and activation of Glp1r dorsal lateral septum neurons in male but not in female mice.

OBJECTIVE: While stress typically reduces caloric intake (hypophagia) in chow-fed rodents, presentation of palatable, high calorie substances during stress can increase caloric consumption (i.e. "comfort feeding") and promote obesity. However, little is known about how obesity itself affects feeding behavior in response to stress and the mechanisms that can influence stress-associated feeding in the context of obesity. METHODS: We assessed food intake and other metabolic parameters in lean and obese male and female mice following acute restraint stress. We also measured real-time activity of glucagon-like peptide-1 (Glp1) receptor (Glp1r)-expressing neurons in the dorsal lateral septum (dLS) during stress in lean and obese mice using fiber photometry. Glp1r activation in various brain regions, including the dLS, promotes hypophagia in response to stress. Finally, we used inhibitory Designer Receptors Activated Exclusively by Designer Drugs (DREADDs) to test whether activation of Glp1r-expressing neurons in the LS is required for stress-induced hypophagia. RESULTS: Lean male mice display the expected hypophagic response following acute restraint stress, but obese male mice are resistant to this acute stress-induced hypophagia. Glp1r-positive neurons in the dLS are robustly activated during acute restraint stress in lean but not in obese male mice. This raises the possibility that activation of dLS Glp1r neurons during restraint stress contributes to subsequent hypophagia. Supporting this, we show that chemogenetic inhibition of LS Glp1r neurons attenuates acute restraint stress hypophagia in male mice. Surprisingly, we show that both lean and obese female mice are resistant to acute restraint stress-induced hypophagia and activation of dLS Glp1r neurons. CONCLUSIONS: These results suggest that dLS Glp1r neurons contribute to the hypophagic response to acute restraint stress in male mice, but not in female mice, and that obesity disrupts this response in male mice. Broadly, these findings show sexually dimorphic mechanisms and feeding behaviors in lean vs. obese mice in response to acute stress.

FGF21 Is an Exocrine Pancreas Secretagogue.

The metabolic stress hormone FGF21 is highly expressed in exocrine pancreas, where its levels are increased by refeeding and chemically induced pancreatitis. However, its function in the exocrine pancreas remains unknown. Here, we show that FGF21 stimulates digestive enzyme secretion from pancreatic acinar cells through an autocrine/paracrine mechanism that requires signaling through a tyrosine kinase receptor complex composed of an FGF receptor and ß-Klotho. Mice lacking FGF21 accumulate zymogen granules and are susceptible to pancreatic ER stress, an effect that is reversed by administration of recombinant FGF21. Mice carrying an acinar cell-specific deletion of ß-Klotho also accumulate zymogen granules but are refractory to FGF21-stimulated secretion. Like the classical post-prandial secretagogue, cholecystokinin (CCK), FGF21 triggers intracellular calcium release via PLC-IP3R signaling. However, unlike CCK, FGF21 does not induce protein synthesis, thereby preventing protein accumulation. Thus, pancreatic FGF21 is a digestive enzyme secretagogue whose physiologic function is to maintain acinar cell proteostasis.

Unexpected effects of the MIP-CreER transgene and tamoxifen on ß-cell growth in C57Bl6/J male mice.

Transgenic mouse models have been fundamental in the discovery of factors that regulate ß-cell development, mass, and function. Several groups have recently shown that some of these models display previously uncharacterized phenotypes due to the transgenic system itself. These include impaired islet function and increased ß-cell mass due to the presence of a human growth hormone (hGH) minigene as well as impaired ß-cell proliferation in response to tamoxifen (TM) administration. We aimed to determine how these systems impact ß-cell mass and proliferation during high fat diet (HFD). To this end, we utilized C57Bl6/J male MIP-CreER mice, which are known to express hGH, or wild-type (WT) mice treated with vehicle corn oil or TM In the absence of TM, MIP-CreER mice fed a chow diet have increased ß-cell mass due to hypertrophy, whereas replication is unchanged. Similarly, after 1 week on HFD, MIP-CreER mice have increased ß-cell mass compared to WT, and this is due to hypertrophy rather than increased proliferation. To assess the impact of TM on ß-cell proliferation and mass, WT mice were treated with vehicle corn oil or TM and then fed a chow diet or HFD for 3 days. We observed that TM-treated mice have improved glucose homeostasis on chow diet but impaired ß-cell proliferation in response to 3 days HFD feeding. These results unveil additional complications associated with commonly used pancreas-specific mouse models.