Buprenorphrine Alters Anxiety-like Behavior in C57BL/6J (B6) Mice as a Function of Dose, Sex, and Obesity

Abstract ID 91916 Poster Board 102 The opioid buprenorphine is used for medication assisted treatment of opioid use disorder (10.1001/jamanetworkopen.2023.34540). Depression and anxiety can be comorbid, and buprenorphine reduces fear recognition in human volunteers (10.1016/j.psyneuen.2012.05.002). Buprenorphine also can produce anxiolysis in humans and rats (10.1016/j.bbr.2021.113651). As a prey species, mice have evolved to avoid open spaces (10.31887/DCNS.2017.19.2/wcarlezon). Accordingly, decreases in the amount of time mice spend in the open portion of an elevated zero maze (EZM) provide an operational measure of anxiety-like behavior (10.3389/fnbeh.2017.00013). Perceived threats evoke flight behavior in mice (10.1523/JNEUROSCI.23-09-03855.2003) which can be assayed as distance traversed in the EZM . This study is testing the hypothesis that systemic administration of buprenorphine alters anxiety-like behaviors of mice on an EZM (Fig. 1A). All methods using mice were reviewed and approved by The University of Tennessee IACUC. Adult, male B6 (n = 10), female B6 (n = 10) and male B6 mice with diet induced obesity (DIO; n = 10) were purchased from the Jackson Laboratory. Mice were injected subcutaneously (0.3 mL) with saline (control) and two doses of buprenorphine (1 and 10 mg/kg). Mice were then placed on the EZM (circumference = 1143 mm) for 5 min, during which time continuous digital video recorded mouse locomotor behavior. Videos were uploaded to a cloud-based Google Drive folder. Locomotor behavior was quantified via predictive modeling using Deep Lab Cut (DLC) (10.1038/s41593-018-0209-y) and simple behavioral analysis (simBA) software (10.7554/ eLife.79305). Dependent measures included total time mice spent in the EZM open region and total distance traveled on the EZM. These measures were analyzed using two way-ANOVA for repeated measures followed by Dunnett's post hoc tests. ANOVA showed that time spent in the open region of the EZM (Fig. 1B) varied significantly as a function of buprenorphine dose (P < 0.0001), mouse line (P = 0.0208), and dose by mouse line interaction (P = 0.0320). Dunnett's analyses revealed sex-dependent differences (P = 0.0006) in time spent in the open EZM region. For distance traveled (Fig. 1C) ANOVA showed a significant effect of buprenorphine dose (P < 0.001) and a mouse line by dose interaction (P = 0.0003). Dunnett's indicated that the distance traveled by males differed significantly from females at both low (P = 0.0005) and high (P = 0.0038) doses of buprenorphine. These effects of buprenorphine are consistent with evidence that mice exhibit sex-dependent differences in anxiety-like behavior (10.1038/s41583-021-00513-0). The data from DIO mice are of interest relative to evidence that depression and anxiety are increased by obesity (10.1016/j.tem.2021.10.005) and co-occur with opioid use disorder (10.1007/s40429-021-00366-8). Considered together these results support the interpretation that among B6 mice buprenorphine differentially alters anxiety-like behavior in a sex- and body mass-dependent manner. Support: The University of Tennessee