ERK1/2 Signaling in the Development of Long-range Projection Neurons

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Description
Development of the central nervous system is an incredible process that relies on multiple extracellular signaling cues and complex intracellular interactions. Approximately 1500 genes are associated with neurodevelopmental disorders, many of which are linked to a specific biochemical signaling cascade…

Development of the central nervous system is an incredible process that relies on multiple extracellular signaling cues and complex intracellular interactions. Approximately 1500 genes are associated with neurodevelopmental disorders, many of which are linked to a specific biochemical signaling cascade known as Extracellular-Signal Regulated Kinase (ERK1/2). Clearly defined mutations in regulators of the ERK1/2 pathway cause syndromes known as the RASopathies. Symptoms include intellectual disability, developmental delay, cranio-facial and cardiac deficits. Treatments for RASopathies are limited due to an in complete understanding of ERK1/2’s role in brain development. Individuals with Neurofibromatosis Type and Noonan Syndrome, the two most common RASopathies, exhibit aberrant functional and white matter organization in non-invasive imaging studies, however, the contributions of neuronal versus oligodendrocyte deficits to this phenotype are not fully understood. To define the cellular functions of ERK1/2 in motor circuit formation, this body of work focuses on two long-range projection neuron subtypes defined by their neurotransmitter. With genetic mouse models, pathological ERK1/2 in glutamatergic neurons reduces axonal outgrowth, resulting in deficits in activity dependent gene expression and the ability to learn a motor skill task. Restricting pathological ERK1/2 within cortical layer V recapitulates these wiring deficits but not the behavioral learning phenotype. Moreover, it is uncovered that pathological ERK1/2 results in compartmentalized expression pattern of phosphorylated ERK1/2. It is not clear whether ERK1/2 functions are similar in cholinergic neuron populations that mediate attention, memory, and motor control. Basal forebrain cholinergic neuron development relies heavily on NGF-TrKA neurotrophic signaling known to activate ERK1/2. Yet the function of ERK1/2 during cholinergic neuronal specification and differentiation is poorly understood. By selectively deleting ERK1/2 in cholinergic neurons, ERK1/2 is required for activity-dependent maturation of neuromuscular junctions in juvenile mice, but not the establishment of lower motor neuron number. Moreover, ERK1/2 is not required for specification of choline acetyltransferase expressing basal forebrain cholinergic neurons by 14 days of age. However, ERK1/2 may be necessary for BFCN maturation by adulthood. Collectively, these data indicate that glutamatergic neuron-autonomous decreases in long-range axonal outgrowth and modest effects on later stages of cholinergic neuron maintenance may be important aspects of neuropathogenesis in RASopathies.
Date Created
2024
Agent

PLUR Responsibly: An evaluation of attitudes regarding drug presence and harm reduction efforts at EDM events by attendees

Description

The electronic dance music (EDM) rave community prides itself in fostering an all- accepting subculture for people to unite in style, song, and dance. Based on the principles of Peace, Love, Unity, and Respect (PLUR), rave events have unique and…

The electronic dance music (EDM) rave community prides itself in fostering an all- accepting subculture for people to unite in style, song, and dance. Based on the principles of Peace, Love, Unity, and Respect (PLUR), rave events have unique and colorful themes, bass levels you can feel in your heart, bright and invigorating laser light shows, and in many cases, a heavy presence of both legal and illegal drug use. Because of the association with illegal substances, open discussions regarding drug presence, use, and harm reduction have been stigmatized and limited in the rave community. This study aims to evaluate the current level of knowledge and attitudes regarding drug presence and harm reduction among “ravers.” All participants were required to be of 18 years of age or older and have attended at least 1 EDM event in the past 5 years. The study involved two stages: (1) collecting qualitative data through in person, phone call, or Zoom interviews (n=14), and (2) collecting quantitative data through closed-ended, anonymous surveys via QuestionPro (n=64). The results indicate that a significant portion of participants in both stages express a desire for easily accessible harm reduction information and increased measures prior to and at EDM events. Starting an open dialogue about drug use and harm reduction efforts within this subculture could help create a safer environment and reduce the negative consequences of drug use.

Date Created
2023-05
Agent

Hippocampal Contributions to the Temporal Dynamics of Behavior

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Description
The capacity to track time in the seconds-to-minutes range, or interval timing, appears to be at least partially dependent on intact hippocampal (HPC) function. The current dissertation sought to dissociate timed responses, non-timed responses, and motivational aspects of behavior in…

The capacity to track time in the seconds-to-minutes range, or interval timing, appears to be at least partially dependent on intact hippocampal (HPC) function. The current dissertation sought to dissociate timed responses, non-timed responses, and motivational aspects of behavior in order to propose a role of the HPC in specific timing sub-processes. In Chapter 2, effects of dorsal HPC (dHPC) lesions on temporal responding in a switch-timing task revealed a critical role of dHPC in the acquisition of interval timing criteria. Following dHPC lesions, the start time of responding was systemically shortened, in a manner that was enhanced and sustained when encoding a novel long interval, consistent with a memory-based account of dHPC function in timed responding. Chapter 3 investigated effects of chronic stress, which has been shown to reliably induce HPC dendritic retraction, on interval timing, utilizing response-initiated schedules of reinforcement, which facilitate deconvolution of timing and motivation. This revealed task-dependent effects on interval timing and motivation, where stress induced transient effects on motivation in a prospective timing task, but transient effects on the variability of timed responding in a retrospective timing task, consistent with an effect on memory function in interval timing. Chapter 4 sought to bring timed responding, motivation, and non-timed behaviors under stronger procedural control, through the implementation of a response-initiated timing-with-opportunity-cost task, in which a cost is imposed on temporal food-seeking by the presence of a concurrent source of probabilistic reinforcement. This arrangement garnered strong schedule control of behavior, and revealed individual-subject differences in the effects of reward devaluation, such that it affected motivation in some rats, but temporal responding in others. Using this methodology, Chapter 5 investigated initial temporal entrainment of behavior under pharmacological deactivation of dHPC and revealed its critical involvement in updating memory to new temporal contingencies. Together, data from this dissertation contrast with prior conclusions that the HPC is not involved in learning temporal criteria, and instead suggest that its function is indeed critical to encoding temporal intervals in memory.
Date Created
2022
Agent

Health & Wealthness Podcast

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Description

“Health and Wealthness” is a podcast where your hosts, Emily Weigel and Hanaa Khan, discuss pressing and trending topics about health and wealth that everyone should know about. Our thesis focuses primarily on the opioid epidemic - the science and business sides.

Date Created
2021-05
Agent

Health & Wealthness Podcast

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Description

Health and Wealthness is a podcast where your hosts, Emily Weigel and Hanaa Khan discuss pressing and trending topics about health and wealth that everyone should know about. Our first four episodes focus on the opioid crisis. Both the science…

Health and Wealthness is a podcast where your hosts, Emily Weigel and Hanaa Khan discuss pressing and trending topics about health and wealth that everyone should know about. Our first four episodes focus on the opioid crisis. Both the science and healthcare sides. We then go on to talk about burnout and mental health in a conversational episode.

Date Created
2021-05
Agent

Non-Traditional Psychotherapy Techniques: An Assessment of the Value of MDMA, Psilocybin and LSD.

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Description

An analysis of the medical the efficacy of MDMA, Psilocybin and LSD as a method of determining the need for psychedelic-based psychotherapy treatments as novel treatments for various psychiatric disorders and how those treatments will be inducted into the United…

An analysis of the medical the efficacy of MDMA, Psilocybin and LSD as a method of determining the need for psychedelic-based psychotherapy treatments as novel treatments for various psychiatric disorders and how those treatments will be inducted into the United States in various formats including healthcare, federal law and social acceptance.

Date Created
2021-05
Agent

Effects of Adolescent Social Isolation on Behavioral Inhibition and Ethanol Preference in Mice

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Description

Exploration of a mouse model (C57BL/6J) capable of demonstrating behavioral changes after adolescent social isolation that are consistent with prior findings may prove beneficial in later research. This study examined 2 proposed long-term effects of isolated housing (one mouse/cage), when…

Exploration of a mouse model (C57BL/6J) capable of demonstrating behavioral changes after adolescent social isolation that are consistent with prior findings may prove beneficial in later research. This study examined 2 proposed long-term effects of isolated housing (one mouse/cage), when compared to group housing (two mice/cage) during adolescence. Mice were placed in their respective housing conditions after weaning (PND 21) and remained in those conditions until PND 60. The same cohorts were used in both phases of the experiment. Phase 1 sought to confirm previous findings that showed increases in ethanol intake after adolescent social isolation using a 2-bottle preference Drinking-in-the-Dark (DID) design over a 4-day period (PND 64-PND 67.). Phase 2 sought to elucidate the effects present after adolescent social isolation, as measured using response inhibition capabilities demonstrated during fixed-minimum interval (FMI) trials (PND 81-PND 111). Findings in phase 1 of the experiment were non-significant, save a strong tendency for female mice in both housing conditions to drink more as a proportion of their bodyweight (g/kg). However, a trend of lower bodyweight in single housed mice did exist, which does suggest that detrimental stress was applied via the used of adolescent isolation in that housing condition. Findings in phase 2 showed little effect of adolescent social isolation on mean inter-response time (IRT) at any criterion used (FMI-0, FMI-4, FMI-6). Evaluation of mean interquartile range (IQR) of IRTs showed a significantly greater amount of variation in IRT responses within single housed mice at the highest criterion (FMI-6), and a trend in the same direction when FMI-4 and FMI-6 were tested concurrently. Taken as a whole, the findings of this experiment suggest that the effect of adolescent social isolation on ethanol intake is far less robust than the effect of sex and may be difficult to replicate in a low-power study. Additionally, adolescent social isolation may interfere with the ability of mice to show consistent accuracy during FMI tasks or a delay in recognition of FMI criterion change.

Date Created
2021-05
Agent

5-HT1B receptor agonist CP 94,253 reduces cocaine intake in female rats post-abstinence and after resuming self-administration

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Description
Approximately five million Americans suffer from cocaine use disorder with no FDA approved pharmaceutical to help their path to recovery (Yerby, 2019). Serotonin is heavily implicated in cocaine use and in the reward system, and is therefore a suggested target…

Approximately five million Americans suffer from cocaine use disorder with no FDA approved pharmaceutical to help their path to recovery (Yerby, 2019). Serotonin is heavily implicated in cocaine use and in the reward system, and is therefore a suggested target for pharmaceuticals aiming to aid in psychostimulant addiction (Sarlin, 2019; Clark and Neumaier, 2001). CP 94,253, a 5-HT1BR agonist, has been shown to increase cocaine intake during maintenance of daily cocaine self-administration, though it has also been shown to decrease intake after a period of forced abstinence (Parsons et al., 1998; Pentowski et al., 2009). While a decrease in cocaine intake post-abstinence is promising post-abstinence, it remains to be seen whether this is a viable option if patients relapse. Most experiments are conducted with male rats, though an increasing amount of data has come to light on the differing effects of drugs on male and female rats (Mennenga and Bimonte-Nelson, 2014). Previous studies conducted through our lab have shown no difference in cocaine self-administration behavior across the estrous cycle phases with CP 94,253. It remains to be seen however, whether CP 94,253 would function dissimilarly in female rats than in male rats. This experiment studied the effects of CP 94,253 on post-abstinence and post-resumption cocaine self-administration in free-cycling female rats across two doses of cocaine. It was shown that CP 94,253 reduces cocaine intake both post-abstinence and post-resumption, suggesting that this pharmacotherapy would work in cases of relapse, and that there are no sex differences in its effects. While more studies should be conducted with locomotion and stress tests, thus far this experiment provides further evidence for the validity of CP 94,253 to be a promising pharmacotherapeutic option for future investigation.
Date Created
2020-05
Agent

A Mouse Model of Serotonin 1B Receptor Modulation of Cocaine and Methamphetamine Craving

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Description
Serotonin 1B receptors (5-HT1BRs) are a novel target for developing pharmacological therapies to reduce psychostimulant craving. 5-HT1BRs are expressed in the mesolimbic pathway projecting from the ventral tegmental area (VTA) to the nucleus accumbens (NAc), which is involved in reward…

Serotonin 1B receptors (5-HT1BRs) are a novel target for developing pharmacological therapies to reduce psychostimulant craving. 5-HT1BRs are expressed in the mesolimbic pathway projecting from the ventral tegmental area (VTA) to the nucleus accumbens (NAc), which is involved in reward and motivation. 5-HT1BR agonists modulate both cocaine- and methamphetamine-seeking behaviors in rat models of psychostimulant craving. In this dissertation, I tested the central hypothesis that 5-HT1BRs regulate cocaine and methamphetamine stimulant and rewarding effects in mice. I injected mice daily with cocaine for 20 days and then tested them 20 days after their last injection. The results showed that the 5-HT1BR agonist CP94253 attenuated sensitization of cocaine-induced locomotion and cocaine-seeking behavior, measured as a decrease in the ability of a cocaine priming injection to reinstate extinguished cocaine-conditioned place preference (CPP). Subsequent experiments showed that CP94253 given prior to conditioning sessions had no effect on acquisition of methamphetamine-CPP, a measure of drug reward; however, CP94253 given prior to testing attenuated expression of methamphetamine-CPP, a measure of drug seeking. To examine brain regions and cell types involved in CP94253 attenuation of methamphetamine-seeking, I examined changes in the immediate early gene product, Fos, which is a marker of brain activity involving gene transcription changes. Mice expressing methamphetamine-CPP showed elevated Fos expression in the VTA and basolateral amygdala (BlA), and reduced Fos in the central nucleus of the amygdala (CeA). In mice showing CP94253-induced attenuation of methamphetamine-CPP expression, Fos was increased in the VTA, NAc shell and core, and the dorsal medial caudate-putamen. CP94253 also reversed the methamphetamine-conditioned decrease in Fos expression in the CeA and the increase in the BlA. In drug-naïve, non-conditioned control mice, CP94253 only increased Fos in the CeA, suggesting that the increases observed in methamphetamine-conditioned mice were due to conditioning rather than an unconditioned effect of CP94253 on Fos expression. In conclusion, 5-HT1BR stimulation attenuates both cocaine and methamphetamine seeking in mice, and that the latter effect may involve normalizing activity in the amygdala and increasing activity in the mesolimbic pathway. These findings further support the potential efficacy of 5-HT1BR agonists as pharmacological interventions for psychostimulant craving in humans.
Date Created
2018
Agent

The Combined Effects of Methamphetamine and Alcohol on Brain Reward Function as Assessed Using Intracranial Self-Stimulation

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Description
Polysubstance abuse is far more common than single substance abuse. One of the most widely abused, yet greatly understudied combination of drugs is the simultaneous use of methamphetamine (meth) and alcohol. Because little research has been conducted on the co-abuse…

Polysubstance abuse is far more common than single substance abuse. One of the most widely abused, yet greatly understudied combination of drugs is the simultaneous use of methamphetamine (meth) and alcohol. Because little research has been conducted on the co-abuse of meth and alcohol, it is important to study the behavioral and neural mechanisms underlying the use of both to combat addiction and come closer to finding an effective treatment of this form of drug abuse. This study uses a rodent model to attempt to identify the mechanisms underlying this co-abuse through the stimulation of the medial forebrain bundle (MFB) and thus the activation of the mesocorticolimbic pathway, the brain's pleasure circuit. First, self-stimulation thresholds (the lowest electrical current the rats are willing to respond for) were determined using a process called Discrete Trials Training. This threshold was later used as a baseline measure to reference when the rats were administered the drugs of abuse: meth and alcohol, both alone and in combination. Our overall results did not show any significant effects of combining alcohol and meth relative to the effects of either drug alone, although subject attrition may have resulted in sample sizes that were statistically underpowered. The results of this and future studies will help provide a clearer understanding of the neural mechanisms underlying the polyabuse of meth and alcohol and can potentially lead to more successfully combating and treating this addiction.
Date Created
2016-12
Agent
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