249— The role of the indirect basal ganglia pathway in a mouse model of repetitive circling behavior

Repetitive behaviors are associated with a variety of disorders in humans and are diagnostic for autism spectrum disorders. Repetitive behaviors can be modeled in rodents. In our previous experiments, we have been able to reduce repetitive circling behaviors in mice using a ketogenic diet. The mechanisms behind the ketogenic diet are still under investigation. Previous investigations have indicated that the ketogenic diet plays a role in neurotransmitter functioning. This study sought to investigate the potential role of neurotransmitters in repetitive behaviors by investigating how three drugs (L-741,626, a dopamine receptor antagonist; CGS21680, an adenosine agonist; & CDPPB, a glutamate positive allosteric modulator) affected circling behavior. Circling behavior was measured using photobeam activated locomotor chambers. Individual doses of each drug as well as a “triple cocktail” consisting of all three drugs were utilized during the experiments. Results indicate that systemic injection of the single drug and triple drug cocktail were not able to reduce circling behavior

055— Ketogenic Diet and Dendritic Morphology in a Mouse Model of Repetitive Behavior

Repetitive motor behaviors are invariant movements with no apparent function. They are associated with several disorders, including autism spectrum disorders (ASD). However, little is known about the causes of these restricted behavior patterns, and effective treatments are lacking. ASD has recently been treated with a ketogenic diet (KD). Now a popular fad, KD is a high-fat, low-carb diet that has treated intractable epilepsy for decades. However, the mechanisms mediating KD’s beneficial effects are still unclear. We first show KD can attenuate repetitive circling behavior. We then assessed dendritic spine density in the left and right dorsolateral striatum as a potential explanation of the reduction of repetitive behavior with KD. Dendritic spine density is a good indicator of the number of synapses in a region, having implications for synaptic transmission. We imaged the striatum as previous research suggests basal ganglia circuitry is impaired in the development of repetitive behavior. Golgi-Cox histochemistry was performed in order to view dendritic spines and dendritic branching patterns. Dendrite length and the number of spines were measured and used to calculate dendritic spine density for each hemisphere. Hemispheric lateralization of dendritic spine density was also explored for an association with the preferred direction of circling

Childhood trauma and post-trauma environment affect fear memory and alcohol use differently in male and female mice

Background: Childhood trauma is associated with the development of adult mental health and substance use disorders, with females generally being more at risk. Alcohol is commonly used for coping with trauma, and alcohol use disorder (AUD) affects ~14.4 million adult Americans annually. Research investigating sex differences in the environmental modification of anxiety and alcohol use following childhood trauma will extend our understanding of the etiology of AUD. Here, we sought to model the interacting effects of a single-episode late childhood trauma with post-trauma environment on adult alcohol use using male and female mice. Methods: C57Bl6/J mice (d22) exposed to predator odor (TMT) or water were reared in standard environments (SE) or environmental enrichment (EE). Mice were assessed for adolescent anxiety and conditioned fear, and for adult alcohol use in a limited access, response non-contingent, alcohol exposure paradigm. Results: A single exposure to predator odor was an effective stressor, inducing long-term sex- dependent changes in conditioned fear and alcohol behaviors that interacted with post-trauma environment. Adolescent EE females showed more conditioned freezing to the trauma-associated context. Adult EE mice consumed less total alcohol than SE mice. However, alcohol use across time differed for males and females. Exposure to a childhood stressor increased alcohol use significantly in females, but not males. EE males, but not EE females, drank less than SE counterparts. Conclusions: Findings from this model recapitulate greater vulnerability to childhood trauma in females and support sex differences in post-trauma development of conditioned fear and alcohol use that are modified by environment

161— The effects of environment on the development of cocaine-seeking

Cocaine addiction is a major individual and societal issue. This study aimed to investigate the environmental and social factors that influence the development of cocaine addiction. Mice were reared in either standard housing or enriched housing. Cocaine preference was measured using the Conditioned Place Preference paradigm, in which subjects are conditioned to associate an injection of cocaine (20mg/kg. I.P.) with a particular side of a 3 chambered arena. Subjects reared in enriched environments displayed increased preference for cocaine in cue primed tests. All subjects displayed cocaine preference in cocaine primed tests. This may be attributed to the enhanced memory that is often seen in mice reared in enriched environments. Future neurobiological assessments will determine if differences exist in the activation patterns of brains from enriched and standard conditions which are associated with the underlying causes of behavior changes, e.g. hippocampus. These assessments will help to shed light on the neural mechanisms associated with cocaine addiction

035— Working Memory and Locomotor Activity in Old and Young Mice Fed a Ketogenic Diet

The ketogenic diet (KD), a high-fat, low-carb diet, has recently been used to treat disorders associated with an inflexibility of cognitive and behavioral routines, such as dementia and autism spectrum disorder. However, there has been little investigation into how KD’s beneficial effects on cognitive behavior may change with age. Here, we show the effects of KD on performance in a working memory task and locomotor activity in young and old C57BL6/J mice. In Experiment 1, we used a Barnes Maze to assess working memory. In the Barnes Maze, mice locate an escape box under a target hole by using spatial cues. Each day the target hole is moved to a new location. We found that mice on KD performed better, indicated by shorter latencies to find the target hole. However, only the young mice on KD made fewer errors. To check for differences in activity between mice on KD and mice fed a normal diet, Experiment 2 employed a 1h locomotor test. KD increased horizontal activity in young and old mice. Thus, regardless of age, mice fed KD performed better in a working memory task and were more active. Findings may be useful for using KD as a therapy

The divergent effects of cdppb and cannabidiol on fear extinction and anxiety in a predator scent stress model of ptsd in rats

Post-traumatic stress disorder (PTSD) currently has no FDA-approved treatments that reduce symptoms in the majority of patients. The ability to extinguish fear memory associations is impaired in PTSD individuals. As such, the development of extinction-enhancing pharmacological agents to be used in combination with exposure therapies may benefit the treatment of PTSD. Both mGlu5 and CB1 receptors have been implicated in contextual fear extinction. Thus, here we tested the ability of the mGlu5 positive allosteric modulator 3-Cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) and cannabidiol (CBD) to reduce both conditioned and unconditioned fear. We used a predator-threat animal model of PTSD which we and others have previously shown to capture the heterogeneity of anxiety responses observed in humans exposed to trauma. Here, 1 week following a 10-min exposure to predator scent stress, rats were classified into stress-Susceptible and stress-Resilient phenotypes using behavioral criteria for elevated plus maze and acoustic startle response performance. Two weeks after classification, rats underwent 3 days of contextual fear extinction and were treated with vehicle, CDPPB or CBD prior to each session. Finally, the light-dark box test was employed to assess phenotypic differences and the effects of CDPPB and CBD on unconditioned anxiety. CDPBB but not CBD, reduced freezing in Susceptible rats relative to vehicle. In the light-dark box test for unconditioned anxiety, CBD, but not CDPPB, reduced anxiety in Susceptible rats. Resilient rats displayed reduced anxiety in the light-dark box relative to Susceptible rats. Taken together, the present data indicate that enhancement of mGlu5 receptor signaling in populations vulnerable to stress may serve to offset a resistance to fear memory extinction without producing anxiogenic effects. Furthermore, in a susceptible population, CBD attenuates unconditioned but not conditioned fear. Taken together, these findings support the use of predator-threat stress exposure in combination with stress-susceptibility phenotype classification as a model for examining the unique drug response profiles and altered neuronal function that emerge as a consequence of the heterogeneity of psychophysiological response to stress. © 2019 Shallcross, Hámor, Bechard, Romano, Knackstedt and Schwendt

159— The effects of trauma on the response to cocaine

Exposure to adverse events is a risk factor for substance use disorder. We modeled this in an inbred strain of mice by exposing adult males to a predator odor (a synthetic fox pheromone, TMT) and then assessing 1. Cocaine-induced locomotion, and 2. Conditioned place preference (CPP) of cocaine. TMT was an effective stressor as indicated by freezing behavior, an absence of movement that is an instinctive fear response in mice. Interestingly, in a 1-hour baseline locomotor test, TMT-exposed (TMT+) mice were more active than non-exposed (TMT-) mice. In addition, following a cocaine (10 mg/kg) injection (i.p.) TMT+ mice showed a cocaine-induced increase in activity, whereas TMT- mice did not. Finally, mice were conditioned to associate one side of a 3-chambered arena with cocaine (10 mg/kg) and were then tested in a 30-minute session of free exploration (15 minutes of cue-prime, 15 minutes of drug-prime). One week later, an identical 30 min session of free exploration was conducted. The time spent inside the drug-associated context was considered an indication of the rewarding properties of cocaine

258— Differential response to cocaine in mice exposed to stress

Exposure to trauma is a risk factor for substance use disorders. Using a mouse model of PTSD, we tested the effects of exposure to a stressor (synthetic fox pheromone: TMT) on response to cocaine. Cocaine induced locomotion and cocaine seeking behavior in a conditioned place preference (CPP) were assessed. TMT was an effective stressor, indicated by freezing behavior, which is a known fear response in mice. In both males and females, TMT-exposed mice showed a greater locomotor response to cocaine compared to control mice, resulting in the interaction between time and TMT treatment. TMT-exposed males, but not females, were overall more active than control mice. During CPP, female mice were first conditioned to associate one side of a 3-chambered arena with cocaine (10 mg/kg) and then tested in a 30-minute session of free exploration (15 minutes of cue-prime, 15 minutes of drug-prime). Time spent inside the drug-associated context was considered an indication of the rewarding properties of cocaine. Results indicated no group differences between female mice exposed to TMT and those that weren’t. Additionally, mice only displayed a preference for the cocaine-paired chamber during cue-primed testing. After receiving a cocaine-prime (10 mg/kg), mice did not continue this behavior

The Divergent Effects of CDPPB and Cannabidiol on Fear Extinction and Anxiety in a Predator Scent Stress Model of PTSD in Rats

Post-traumatic stress disorder (PTSD) currently has no FDA-approved treatments that reduce symptoms in the majority of patients. The ability to extinguish fear memory associations is impaired in PTSD individuals. As such, the development of extinction-enhancing pharmacological agents to be used in combination with exposure therapies may benefit the treatment of PTSD. Both mGlu5 and CB1 receptors have been implicated in contextual fear extinction. Thus, here we tested the ability of the mGlu5 positive allosteric modulator 3-Cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) and cannabidiol (CBD) to reduce both conditioned and unconditioned fear. We used a predator-threat animal model of PTSD which we and others have previously shown to capture the heterogeneity of anxiety responses observed in humans exposed to trauma. Here, 1 week following a 10-min exposure to predator scent stress, rats were classified into stress-Susceptible and stress-Resilient phenotypes using behavioral criteria for elevated plus maze and acoustic startle response performance. Two weeks after classification, rats underwent 3 days of contextual fear extinction and were treated with vehicle, CDPPB or CBD prior to each session. Finally, the light-dark box test was employed to assess phenotypic differences and the effects of CDPPB and CBD on unconditioned anxiety. CDPBB but not CBD, reduced freezing in Susceptible rats relative to vehicle. In the light-dark box test for unconditioned anxiety, CBD, but not CDPPB, reduced anxiety in Susceptible rats. Resilient rats displayed reduced anxiety in the light-dark box relative to Susceptible rats. Taken together, the present data indicate that enhancement of mGlu5 receptor signaling in populations vulnerable to stress may serve to offset a resistance to fear memory extinction without producing anxiogenic effects. Furthermore, in a susceptible population, CBD attenuates unconditioned but not conditioned fear. Taken together, these findings support the use of predator-threat stress exposure in combination with stress-susceptibility phenotype classification as a model for examining the unique drug response profiles and altered neuronal function that emerge as a consequence of the heterogeneity of psychophysiological response to stress