Vendor differences in anxiety-like behaviors in female and male Sprague Dawley rats

Although Sprague Dawley outbred rats are commonly used in behavioral, physiological, and pharmacological studies, dramatic differences in responses may emerge from rats obtained from different suppliers even when sex, age, and environmental conditions are maintained constant. In the present study, we compared behavioral responses on three tests related to anxiety of Sprague Dawley female and male rats obtained from three different vendors in the United States: Charles River, Envigo, and Taconic. All rats were tested in the open field, light-dark box, and elevated zero maze. We found reduced time spent in the center area of the open field and decreased light compartment duration in the light-dark box test in female and male rats from Taconic compared to Charles River and Envigo rats, suggesting anxiety-like behaviors differ between the three vendors. No vendor differences were found on performance in the elevated zero maze. Furthermore, the contribution of stress hormones to vendor differences was examined by measuring serum corticosterone levels in rats 30 min after exposure to the elevated zero maze. There were no vendor differences in corticosterone levels, suggesting that endogenous levels of stress hormones most likely did not contribute to vendor differences in anxiety-like behaviors. Collectively, these findings highlight the importance of vendor selection of the Sprague Dawley stock for research involving behavioral tests related to anxiety.

Are we moving the dial? Canadian health research funding trends for women's health, 2S/LGBTQ + health, sex, or gender considerations

BACKGROUND

Sex and gender impacts health outcomes and disease risk throughout life. The health of women and members of the Two-Spirit, Lesbian, Gay, Bisexual, Transgender, Queer or Questioning (2S/LGBTQ +) community is often compromised as they experience delays in diagnosis. Distinct knowledge gaps in the health of these populations have prompted funding agencies to mandate incorporation of sex and gender into research. Sex- and gender-informed research perspectives and methodology increases rigor, promotes discovery, and expands the relevance of health research. Thus, the Canadian Institutes of Health Research (CIHR) implemented a sex and gender-based analysis (SGBA) framework recommending the inclusion of SGBA in project proposals in 2010 and then mandating the incorporation of SGBA into grant proposals in 2019. To examine whether this mandate resulted in increased mention of sex or gender in funded research abstracts, we searched the publicly available database of grant abstracts funded by CIHR to analyze the percentage of abstracts that mentioned sex or gender of the population to be studied in the funded research. To better understand broader health equity issues we also examined whether the funded grant abstracts mentioned either female-specific health research or research within the 2S/LGBTQ + community.

RESULTS

We categorized a total of 8,964 Project and Operating grant abstracts awarded from 2009 to 2020 based on their study of female-specific or a 2S/LGBTQ + populations or their mention of sex or gender. Overall, under 3% of grant abstracts funded by CIHR explicitly mentioned sex and/or gender, as 1.94% of grant abstracts mentioned sex, and 0.66% mentioned gender. As one of the goals of SGBA is to inform on health equity and understudied populations with respect to SGBA, we also found that 5.92% of grant abstracts mentioned female-specific outcomes, and 0.35% of grant abstracts focused on the 2S/LGBTQ + community.

CONCLUSIONS

Although there was an increased number of funded grants with abstracts that mentioned sex and 2S/LGBTQ + health across time, these increases were less than 2% between 2009 and 2020. The percentage of funded grants with abstracts mentioning female-specific health or gender differences did not change significantly over time. The percentage of funding dollars allocated to grants in which the abstracts mentioned sex or gender also did not change substantially from 2009 to 2020, with grant abstracts mentioning sex or female-specific research increasing by 1.26% and 3.47%, respectively, funding allocated to research mentioning gender decreasing by 0.49% and no change for 2S/LGBTQ +-specific health. Our findings suggest more work needs to be done to ensure the public can evaluate what populations will be examined with the funded research with respect to sex and gender to advance awareness and health equity in research.

Kappa opioid receptor mediated operant performance in male and female rats

Anhedonia and avolition are emotions frequently endorsed by individuals with stress related disorders. Kappa opioid receptor (KOR) activation can induce negative emotions and recent clinical evidence suggests that KOR antagonism can alleviate anhedonia in a transdiagnostic cohort of patients. However, the behavioral consequences of KOR activation and antagonism in modulating motivation, as assessed by schedule-controlled behavioral performance without preexisting conditions (stress or substance use), have not been formally assessed. To address this gap in the literature, this report utilized male and female Sprague Dawley rats to (1) evaluate the impact of the selective KOR agonist U50,488, on the performance of animals responding for sucrose pellets under a progressive ratio (PR) schedule and (2) determine the effects of the short-acting KOR antagonist LY2444296 alone and on U50,488 mediated reductions in PR performance. Overall, U50,488 5 mg/kg significantly reduced the breakpoint and number of rewards obtained by animals. This occurred in the absence of motor impairment and independent of evidence for satiation. LY2444296 did not alter PR performance when administered alone but effectively blocked the deficits induced by U50,488. To further delineate the behavioral alterations that underlie these reductions in responding, a more detailed analysis was conducted on PR performance in the first 15 min of the session, the period of time when animals obtained the most reinforcers. During this period, U50,488 increased the length of the post-reinforcement pause and reduced the running rate on PR schedules. These changes in behavior produced by acute activation of KORs are consistent with a reduction of effort-related motivation in rodents. These data contribute to the understanding of how KORs modulate motivation, which is critical to future efforts to evaluate performance in the context of stress and assess how KOR antagonists alleviate anhedonic behaviors associated with stress.

Buprenorphine as a Treatment for Major Depression and Opioid Use Disorder

Rates of major depressive disorder (MDD) are disproportionally high in subjects with opioid use disorder (OUD) relative to the general population. MDD is often more severe in OUD patients, leading to compliance issues with maintenance therapies and poor outcomes. A growing body of literature suggests that endogenous opioid system dysregulation may play a role in the emergence of MDD. Buprenorphine, a mixed opioid receptor agonist/antagonist approved for the treatment of OUD and chronic pain, may have potential as a novel therapeutic for MDD, especially for patients with a dual diagnosis of MDD and OUD. This paper presents a comprehensive review of papers relevant to the assessment of buprenorphine as a treatment for MDD, OUD, and/or suicide compiled using electronic databases per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The principal goal of this literature review was to compile the clinical studies that have interrogated the antidepressant activity of buprenorphine in opioid naïve MDD patients and OUD patients with comorbid MDD. Evidence supporting buprenorphine's superiority over methadone for treating comorbid OUD and MDD was also considered. Finally, recent evidence for the ability of buprenorphine to alleviate suicidal ideation in both opioid-naïve patients and opioid-experienced patients was evaluated. Synthesizing all of this information, buprenorphine emerges as a potentially effective therapeutic for the dual purposes of treating MDD and OUD.

Canadian Health Research Funding Patterns for Sexual and Gender Minority Populations Reflect Exclusion of Women

Purpose: We explored the funding areas of Two-Spirit, lesbian, gay, bisexual, transgender (trans), queer or questioning, and intersex individuals (2S/LGBTQI)-specific health research funded by the Canadian Institutes of Health Research (CIHR) mentioned in the grant abstracts. Methods: We analyzed the publicly available database of grant abstracts funded by CIHR from 2009-2020 to examine what types of 2S/LGBTQI-specific health outcomes would be studied and in what populations. Results: We found that 58% of awarded grant abstracts mentioned studying sexually transmitted diseases, the majority of which was on human immunodeficiency virus. Of the funded 2S/LGBTQI grant abstracts that specified the gender of the population to be studied (n=23), less then 9% mentioned studying cisgender women. Almost 40% mentioned including trans women/girls, and 30% mentioned including trans men/boys. None of the studies examined mentioned work with the Two-Spirit community. Conclusion: These results reflect larger social and health inequities that require structural level changes in research to support the 2S/LGBTQI community.