Fall Research Expo 2020

Classifying Ultrasonic Vocalization Subtypes During Oxycodone Self-Administration in Male Rats

Opioid abuse is a rampant problem in the United States, claiming the lives of over 47,000 individuals in 2018 alone. Understanding opioid abuse  – how and why individuals administer substances  to the point of dependence  – remains critically important in the development of treatments for opioid use disorders. Opioids are known to produce subjectively positive feelings from humans, underscoring their abuse potential, however this has been difficult to study in animals. Intriguingly, rats make high-pitched vocal emissions called ultrasonic vocalizations (USVs), and previous work suggests that USVs act as both a communication tool and an emotional marker. Specifically, numerous studies support that USVs ~22-kHz in frequency are emitted in situations evoking a negative emotional state, whereas USVs ~50-kHz mark a positive emotional state. More recently, researchers in the addiction field have come to realize that within the 50-kHz range of USVs, there are numerous subtypes with potential functional relevance. Thus, the question is whether these subtypes represent more specific emotions that can then be used to further understand the forces behind addiction. Using male rats in an oxycodone self administration experiment, we studied if and how different 50-kHZ USV subtypes changed in frequency at different timepoints in the acquisition phase. These timepoints were before the lever (used for drug infusion) extended, after the lever extended, and then 20 seconds after the first 10 infusions on Days 1, 7 and 13. Our preliminary data suggests two major trends during the pre-lever timepoint: 1) there is a decrease in the number of fixed frequency (FF) USVs throughout the sessions and  2) on Days 7 and 13, the majority of the USVs belong to the Sweep with 1 modulation (SW1) and Step with 1 modulation (ST1) subtypes.

PRESENTED BY
Grants for Faculty Mentoring Undergraduate Research
College of Arts & Sciences 2023
Advised By
Amelia J. Eisch, Ph.D
Professor in Departments of Anesthesiology and Critical Care Medicine and Neuroscience
PRESENTED BY
Grants for Faculty Mentoring Undergraduate Research
College of Arts & Sciences 2023
Advised By
Amelia J. Eisch, Ph.D
Professor in Departments of Anesthesiology and Critical Care Medicine and Neuroscience

Comments

Haley, is there evidence that vocalizations differ between male and female rats consuming opioids? There is some evidence supporting sex differences in the development of opioid use disorders so I am wondering if you see vocalization patterns between sexes that may reflect these differences. 

Great poster! Is there any data on long-term opioid use in rats? I'm curious whether the trends dampen at all as the addiction develops and tolerance increases.

Very nice job on the poster, the written summary, and the delivery of the written summary! Question: how far did the team get in employing DeepSqueak, and what are the obstacles we need to surmount to use it both in a simple way but also in a way that utilizes the different types of USVs you indicate in your poster? I also want to know how long you think it takes you to do one of these analyses :) basically, wondering how much time you would need for each additional rat point as you increase your "N". Basically I am just looking at your future in the lab and dreaming of all the additional cool things you will able to work on!

This research sounds fascinating, and it is so cool how research on rats can be applied to one of the biggest human issues of our time.

Haley, I am impressed with your results and so glad to see you engaged in such important and substantive research.

Oxycodone is one of the prescription opioid gateway drugs to heroin.  Found in Percocet (acetaminophen 325 mg plus oxycodone 5 mg).  One of the reasons the "smart" prescription opioid misuser or abuser transitions to heroin is because while they become tolerant to higher and higher doses of oxycodone (need more to get high and need more to overdose), they don't become tolerant to the acetaminophen which at high doses will cause permanent if not fatal liver injury.  So they transition to a pure opioid and heroin fits the bill and is cheap on the streets.