Chemogenetic activation of corticotropin-releasing factor-expressing neurons in the anterior bed nucleus of the stria terminalis reduces effortful motivation behaviors.

Corticotropin-releasing factor (CRF) in the anterior bed nucleus of the stria terminalis (aBNST) is associated with chronic stress and avoidance behavior. However, CRF + BNST neurons project to reward- and motivation-related brain regions, suggesting a potential role in motivated behavior. We used chemogenetics to selectively activate CRF+ aBNST neurons in male and female CRF-ires-Cre mice during an effort-related choice task and a concurrent choice task. In both tasks, mice were given the option either to exert effort for high value rewards or to choose freely available low value rewards. Acute chemogenetic activation of CRF+ aBNST neurons reduced barrier climbing for a high value reward in the effort-related choice task in both males and females. Furthermore, acute chemogenetic activation of CRF+ aBNST neurons also reduced effortful lever pressing in high-performing males in the concurrent choice task. These data suggest a novel role for CRF+ aBNST neurons in effort-based decision and motivation behaviors.

Surge of Midazolam Use in the Midst of Lorazepam Shortage.

BACKGROUND: Lorazepam is a widely prescribed benzodiazepine that is used to manage anxiety, insomnia, and status epilepticus and is used for pre-anesthetic care as well as several off-label indications including aggression, alcohol withdrawal, panic disorder, chemotherapy-associated anticipatory nausea, and catatonia. Recent increases in demand, manufacturing changes, and quality control issues have resulted in a shortage of injectable and oral lorazepam, prompting clinicians to use alternatives. One such alternative is midazolam, a drug that has been used primarily in the intensive care unit and anesthesia settings. PROCEDURES: This article examines the significant pharmacologic differences between lorazepam and midazolam. In addition, this article provides dosage guidelines based on the current scientific knowledge and recommendations for conversion equivalencies. RESULTS: The clinical preference for lorazepam can be attributed to its simpler metabolism with no active metabolites, better suitability for patients with less severe hepatic and renal impairment, less risk of adverse reactions, fewer drug-drug interactions, and greater desirability for special populations. In periods of shortages, midazolam has been shown to be effective for a number of off-label uses. To manage conditions that have not been extensively studied, clinicians may opt to use conversion equivalencies, with the caveat that guidelines may vary greatly between institutions and online sources; therefore, it would be best to start low and titrate slowly. CONCLUSIONS: Our goal is to aid clinicians in safely and effectively prescribing midazolam during the shortage of injectable lorazepam so that patients are provided the same effects and benefits.

Elevated levels of tripeptidyl peptidase 1 do not ameliorate pathogenesis in a mouse model of Alzheimer disease.

One potential therapeutic strategy for Alzheimer disease (AD) is to promote degradation of amyloid beta (Aß) and we previously demonstrated that the lysosomal protease tripeptidyl peptidase 1 (TPP1) can degrade Aß fibrils in vitro. In this study, we tested the hypothesis that increasing levels of TPP1 might promote degradation of Aß under physiological conditions, slowing or preventing its accumulation in the brain with subsequent therapeutic benefits. We used 2 approaches to increase TPP1 activity in the brain of J20 mice, an AD model that accumulates Aß and exhibits cognitive defects: transgenic overexpression of TPP1 in the brain and a pharmacological approach employing administration of recombinant TPP1. While we clearly observed the expected AD phenotype of the J20 mice based on pathology and measurement of behavioral and cognitive defects, we found that elevation of TPP1 activity by either experimental approach failed to have any measurable beneficial effect on disease phenotype.

Engrailed 2 deficiency and chronic stress alter avoidance and motivation behaviors.

Autism spectrum disorder (ASD) is a pervasive neurodevelopmental disorder characterized by impairments in social interaction, cognition, and communication, as well as the presence of repetitive or stereotyped behaviors and interests. ASD is most often studied as a neurodevelopmental disease, but it is a lifelong disorder. Adults with ASD experience more stressful life events and greater perceived stress, and frequently have comorbid mood disorders such as anxiety and depression. It remains unclear whether adult exposure to chronic stress can exacerbate the behavioral and neurodevelopmental phenotypes associated with ASD. To address this issue, we first investigated whether adult male and female Engrailed-2 deficient (En2-KO, En2-/-) mice, which display behavioral disturbances in avoidance tasks and dysregulated monoaminergic neurotransmitter levels, also display impairments in instrumental behaviors associated with motivation, such as the progressive ratio task. We then exposed adult En2-KO mice to chronic environmental stress (CSDS, chronic social defeat stress), to determine if stress exacerbated the behavioral and neuroanatomical effects of En2 deletion. En2-/- mice showed impaired instrumental acquisition and significantly lower breakpoints in a progressive ratio test, demonstrating En2 deficiency decreases motivation to exert effort for reward. Furthermore, adult CSDS exposure increased avoidance behaviors in En2-KO mice. Interestingly, adult CSDS exposure also exacerbated the deleterious effects of En2 deficiency on forebrain-projecting monoaminergic fibers. Our findings thus suggest that adult exposure to stress may exacerbate behavioral and neuroanatomical phenotypes associated with developmental effects of genetic En2 deficiency.

Chronic non-discriminatory social defeat stress reduces effort-related motivated behaviors in male and female mice.

Reward and motivation deficits are prominent symptoms in many mood disorders, including depression. Similar reward and effort-related choice behavioral tasks can be used to study aspects of motivation in both rodents and humans. Chronic stress can precipitate mood disorders in humans and maladaptive reward and motivation behaviors in male rodents. However, while depression is more prevalent in women, there is relatively little known about whether chronic stress elicits maladaptive behaviors in female rodents in effort-related motivated tasks and whether there are any behavioral sex differences. Chronic nondiscriminatory social defeat stress (CNSDS) is a variation of chronic social defeat stress that is effective in both male and female mice. We hypothesized that CNSDS would reduce effort-related motivated and reward behaviors, including reducing sensitivity to a devalued outcome, reducing breakpoint in progressive ratio, and shifting effort-related choice behavior. Separate cohorts of adult male and female C57BL/6 J mice were divided into Control or CNSDS groups, exposed to the 10-day CNSDS paradigm, and then trained and tested in instrumental reward or effort-related behaviors. CNSDS reduced motivation to lever press in progressive ratio and shifted effort-related choice behavior from a high reward to a more easily attainable low reward in both sexes. CNSDS caused more nuanced impairments in outcome devaluation. Taken together, CNSDS induces maladaptive shifts in effort-related choice and reduces motivated lever pressing in both sexes.