Program Descriptions

Branch, A’sha^1,2, Keller, Courtney¹, Goeders, Nicholas^1
1Department of Pharmacology, Toxicology & Neuroscience, LSU Health Shreveport, Shreveport, LA
²Department of Biology, Jackson State University, Jackson, MS

The well-known and considerably non-addictive drug gabapentin is typically prescribed for nerve pain management, but also used for many other off-label symptoms. Conditions such as epilepsy, shingles, and sometimes even mental illness are treated by gabapentin. Previous studies have called both the efficacy and the abuse potential of the drug into question, and both have been found to vary, like many other drugs, based on the individual, as well as the dosage of the prescription and other factors. Interestingly, we found in a previous study that rats will self-administer gabapentin at rates greater than saline, suggesting that gabapentin does in fact have abuse potential. Ongoing research strives to delve into the consequence gabapentin has on previously established methamphetamine (MA) use disorder. Since gabapentin has been shown to be abused by individuals and rats, we hypothesized that gabapentin would increase the reinforcing effects of MA. Male and female rats were trained to self-administer MA (0.03 mg/kg/infusion) on a fixed-ratio 4 schedule of reinforcement. Following stable self-administration, MA was replaced with either saline or a combination of gabapentin (2.5, 5, or 10 mg/kg/inf) and MA. On average, the addition of gabapentin to MA attenuated the reinforcing effects of MA at all three doses of gabapentin. However, there was considerable variability between subjects. Of the three rats that were tested, one had dramatic reductions in responding when gabapentin was added to MA (>90%), one had medium reductions (~50%), and the final rat had no change in responding. While more subjects need to be added to the study, the results do not support our hypothesis. Gabapentin may actually attenuate the reinforcing effects of MA. This suggests that gabapentin and/or drugs with a similar mechanism of action could be beneficial for treating MA use disorder.

Chace, Natalie¹; Haacker, Clifton²; Jiyu Li², Lu, Xiao-Hong^2
1Connecticut College, New London, CT; ² Department of Pharmacology, Toxicology, and Neuroscience, School of Medicine, LSU Health Shreveport, Shreveport, LA

Aging is a complex process and often comes with susceptibility to injury, including instability at the cellular level. Aging is a critical risk factor for Alzheimer’s Disease, cancer, cardiovascular diseases, and more.¹ One of the main factors associated with aging is DNA damage, so studying DNA damage on cell function is pertinent, especially with exposure to damaging agents including COVID-19², pesticides³, and radiation⁴ and to protect against brain degeneration of the growing elderly population⁵. The DNA damage response can result in senescence in most cells, but it is unclear which brain cells can undergo senescence and contribute to chronic neuroinflammation that accelerates aging and cognitive decline. We hypothesize that aging or exposure to DNA-damaging environmental risk factors can induce senescence in microglial cells and that blocking the DNA damage response can prevent microglial senescence. We examined senescence and ATM inhibitors in BV2 cells by studying morphology and senescence staining and used a live cell p21 fluorescent tracker in vitro. In vivo, aged mice were given a viral vector to inhibit ATM to determine if obstructing the DNA damage response can reverse microglial activation. For these, the microglia size and count were compared to determine microglial activation between a group given the virus and a control. The study aims to provide mechanistic insights into the pathogenic role of DNA damage in brain aging and neurodegenerative disorders and propose novel therapeutic approaches to prevent brain aging.

A low dose of doxorubicin, 50nM in BV2 cells robustly decreased cell proliferation and induced cell senescence and an ATM inhibitor reduced these effects. In aged mice, the viral vector to inhibit ATM reduced microglial reactivity and chronic neuroinflammation. This data overall suggests that DNA damage is mechanistically involved in senescence in microglia. ATM inhibitors may be able to rescue or prevent the damaging pro-inflammatory qualities of microglia that have undergone DNA damage, which may help protect against the neurodegenerative effects of aging.

Acknowledgement: LSUHS SUPER program, Dept of Toxicology, Pharmacology, and Neuroscience, and funding from NASA and NIH to Lu lab.

References

1. Guo, J., Huang, X., Dou, L. et al. Aging and aging-related diseases: from molecular mechanisms to interventions and treatments. Sig Transduct Target Ther 7, 391 (2022).

2. Pánico, P., Ostrosky-Wegman, P., & Salazar, A. M. (2022). The potential role of COVID-19 in the induction of DNA damage. Mutation Research/Reviews in Mutation Research, 789, 108411.

3. Ledda, C., Cannizzaro, E., Cinà, D. et al. Oxidative stress and DNA damage in agricultural workers after exposure to pesticides. J Occup Med Toxicol 16, 1 (2021).

4. Huang, RX., Zhou, PK. DNA damage response signaling pathways and targets for radiotherapy sensitization in cancer. Sig Transduct Target Ther 5, 60 (2020).

5. Schumacher, B., Pothof, J., Vijg, J. et al. The central role of DNA damage in the ageing process. Nature 592, 695–703 (2021).

Deaver, Lindsey^1,2; Jacquet, Noel¹; Zhao, Yunfeng^{1 1}Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Science Center, Shreveport, LA.
²Department of Biological Sciences, Louisiana State University-Shreveport

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer. HCC is the third leading cause of death from cancer. According to the American Cancer Society, the incidence and mortality rates of liver cancer are steadily increasing. Because of the high incidence and mortality rates, new drug therapies and treatments must be developed to stop the incidence and mortality rates from further increasing. New drug targets need to be developed because the current therapies for HCC are not highly effective. Cancer cells tend to acquire characteristics that make them more oncogenic including, sustained proliferative signaling, resisting cell death, evading destruction from immune cells, inducing angiogenesis, and many others. ADCK1, a protein with a potential cytosolic or mitochondrial location, could be linked to HCC’s pro-cancerous capabilities. Data from the GEPIA database have shown a negative correlation between patient survival and high expression of ADCK1. Because of this, ADCK1 could potentially be a target for new drug therapies. Our lab has generated ADCK1 knockout clones via infection of HCC cells lines, SNU-449 and HepG2, with a lentivirus containing restriction enzymes targeting ADCK1. Our lab examined HCC’s sustained proliferative signaling abilities through cell cycle analysis using flow cell cytometry. Our results showed that ADCK1 expression influenced proliferative signaling and cell cycle progression.

Emma S. Patenode^1,2, Bo J. Wood^1,3, M. Frances Vest^1,3, Catharine M. Carfagno^1,3, Ethan D. Brackett¹, Bruce Blough⁵, Kevin S. Murnane^1,3,4

¹Department of Pharmacology, Toxicology, & Neuroscience, LSU Shreveport, Shreveport, LA
²College of Health Sciences, Gonzaga University
³Louisiana Addiction Research Center, Shreveport, LA
⁴Department of Psychiatry and Behavioral Medicine, LSU Health Shreveport, Shreveport, LA
⁵Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC 4

As research continues to grow on the use of psychedelics for the treatment of psychiatric disorders, psilocybin, and its active metabolite, psilocin, are the most promising options as they have shown favorable anxiolytic and antidepressant effects. However, the legal status of psilocybin as a Schedule 1 substance has caused many to consider alternative options, such as synthetic compounds derived from psilocybin and other existing psychoactive drugs. There has been little research on novel psilocybin analogs and their properties, which is needed to broaden our understanding of the therapeutic landscape of psychedelics. Developing synthetic compounds derived from psilocybin offers the opportunity to discover analogs with improved efficacy, reduced side effects, and greater accessibility in a clinical setting.

We aimed to gain a deeper understanding of the psychoactive and anxiolytic properties of three synthetic analogs of psilocin (4-HO-DMT): 4-Hydroxy-N-isopropyltryptamine (4-HO-NiPT), 4-Hydroxy-N-Methyl-N-isopropyltryptamine (4-HO-MiPT), and 4-Hydroxy-Diisopropyltryptamine (4-HO-DiPT). To accomplish this, we determined the dose of each compound that elicited the greatest head twitch response and then tested that dose for anxiolytic-like effects using an elevated zero maze. Head twitches are a rapid side-to-side rotational movement that occurs in mice with activation of serotonin 2A (5-HT2A) receptors, which is believed to relate to psychedelic experiences in humans. Due to this, the head twitch response was used to determine the psychoactive effect of 4-HO-NiPT, 4-HO-MiPT, and 4-HO-DiPT. To determine a peak dose, we administered mice via I.P. injection with each compound at various doses and the number of head twitches over a 10-minute period was recorded. The dose with the highest number of head twitches was chosen as the peak dose and used for the elevated zero maze. For this assay, the latency to enter open arms, number of open arm entries, and time spent in open arms was recorded.

We observed the same peak dose (3.2 mg/kg) for psilocin, 4-HO-DiPT, and 4-HO-MiPT, while 4-HO-NiPT had a higher peak dose (32 mg/kg). There was no significant difference in the number of head twitches elicited at each compound’s peak dose. However, psilocin induced the fewest head twitches, while 4-HO-MiPT and 4-HO-DiPT induced the most. Interestingly, the elevated zero maze data did not align with the head twitch response, suggesting that the anxiolytic effects may have occurred independently of the 5-HT2A receptor. Notably, 4-HO-DiPT exhibited significant acute anxiolytic effects compared to saline, despite showing no significant difference from the other compounds in the head twitch response. For head twitch and elevated zero assays, we noticed a strong variability in each individual mouse’s response to the drug; future analysis of psychedelic response in mice may reflect genetic predispositions that cause different responses.

Liane Pham¹, Deirdre A. Thornton¹, Adesewa Akande¹, Hyung. W. Nam¹

¹ Department of Pharmacology, Toxicology and Neuroscience, LSU Health Shreveport, LA

Alcohol use disorder (AUD) develops from prolonged and excessive alcohol consumption resulting to an increased tolerance and alcohol intake to produce the same effects. This disorder significantly impacts the brain by reducing and thinning the cortex, primarily the prefrontal cortex, which is crucial for cognitive function. With alcohol exposure, these functions undergo alteration and structural changes in the brain that may persist even after achieving abstinence, potentially hindering neuroplasticity, and cognitive recovery, thereby increasing the risk of relapse. However, the effect of chronic alcohol self-administration on cortical functioning remains unclear. We hypothesize that abstaining from alcohol can potentially reverse alcohol-induced cognitive impairments. To examine this, mice were treated with 8 sessions of self-administer alcohol or oral gavage. Among many cortical functional measurements, we employed alcohol-induced ataxia and sensorimotor. Sensorimotor gating is measured by Pre-pulse inhibition (PPi), which measures the brain’s ability to filter out unnecessary sensory stimuli to improve concentration and prevent sensory overload. There is no change in alcohol-induced ataxia between the alcohol and sucrose control group in both alcohol self-administration and oral gavage. Notably, both chronic alcohol self-administration and oral gavage showed significantly decreased PPi response, which indicates alcohol-induced cognitive impairments. Overall, our study demonstrates the impact of chronic alcohol administration decreases PPi, which is validated by both self-administration and oral gavage.