Do ultrasonic vocalizations during intermittent swim stress forecast subsequent alcohol reactivity?. Molly Williams 2 , Nathaniel Stafford 1 and Robert Drugan 1 1 Psychology Department, University of New Hampshire, Durham, NH 03824, USA
Do ultrasonic vocalizations during intermittent swim stress forecast subsequent alcohol reactivity?
Molly Williams2 , Nathaniel Stafford1 and Robert Drugan1
1Psychology Department, University of New Hampshire, Durham, NH 03824, USA
2Neuroscience and Behavior, University of New Hampshire, Durham, NH 03824, USA
Intermittent Swim Stress (ISS)
Anxiety disorders affect 18.1% of adults in the United States. Anxiety is a normal response to stress. In abnormal amounts, however, stress can cause disorders such as generalized anxiety disorder, obsessive compulsive disorder, panic disorder, post-traumatic stress disorder and depression. According to the National Institute of Mental Health, only 36.9% of those with an anxiety disorder are receiving treatment and 34.3% of those are receiving a minimally adequate treatment (NIMH 2009). The implications of treatment deficiency demonstrate the need for further investigation of stress related disorders in order to continue to improve quality of life for those suffering from the effects of stress and anxiety. Those who do not receive successful professional treatment often resort to dangerous self-medication with alcohol, as it is often perceived as an effective coping mechanism (Robinson, Sareen, Cox, Bolton 2009).
Alcohol is known to be a central nervous system (CNS) depressant, impairing reaction time, balance, and motor coordination through its action on GABA receptors in the CNS. As both alcohol and stress act on a common neurotransmitter site in the brain, GABA-BDZ, subsequent studies have found that stressed rats react more strongly to drugs that act on this site, such as ethanol, when compared to non-stressed controls (Drugan et al., 1992; Austin, Myles, Brown 1999). This suggests that self-medication during stress may result in an increase in the reinforcing effects of alcohol and thereby lead to alcohol abuse and possibly addiction.
Previous studies have also investigated the implications of uncontrollable versus controllable shock stress, finding that only those rats that cannot control the stressor will exhibit greater sleep time and motor ataxia as a result of ethanol administration (Drugan et al., 1992; Drugan et al., 1996). Recent evidence in a new swim stress model suggests that resilience can be seen in rats that do not have the opportunity for active behavioral coping, yet emit significant amounts of ultrasonic vocalizations (USV). The ISS model has been shown to result in anxiety and depression (Christianson and Drugan 2005; Warner et al., 2013).
Rats that exhibit high amounts of vocalizations will show reduced reactivity to alcohol in comparison to non callers.
24 male Sprague-Dawley rats weighing 250-300 g were used for the experiment. The rats were housed four per cage in the vivarium with free access to food and water on a 12-hour light/dark cycle. The lights were on at 6:00 am. The rats were randomly assigned to one of four groups: CC/saline, ISS/saline, CC/Ethanol, ISS/ethanol.
20% ethanol was administered intraperitoneally at a dose of 0.6 mg/kg of the animal’s body weight. The control group received an equal volume of 0.9% saline.
Motor ataxia was measured using the Rotarod treadmill model 7700 . The rotarod has a diameter of 6cm and is 35cm in length and rotates at a constant speed of 10 rotations per minute.
(Below) One stress animal is lowered into water by cylinder on the left while a control is simultaneously lowered in the shorter cylinder. Rats were warmed with fans between trials.
Austin, M., Myles, V., Brown, P.L, Mammola, B., Drugan, R. (1999). FG 7142- and Rat Induced Alterations in the Ataxic Effects of Alcohol and Midazolam in Rats are Time Dependent. Pharmacology Biochemistry and Behavior, 62, 45-51.
Christianson, J.P, Drugan, R. (2005) Intermittent cold water swim stress increases immobility and interferes with escape performance in rat. Behavioral Brain Research, 165(1):58-62
Drugan, R. C, Christianson, J. P, Warner, T. A, Kent, S. (2013). Resilience in shock and swim stress models of depression. Frontiers in behavioral neuroscience. 7(14):1-8.
Drugan, R.C, Coyle, T.S, Healy, D.J, Chen, S. (1996). Stress Controllability Influences the Ataxic Properties of Both Ethanol and Midazolam in the Rat. Behavioral Neuroscience, 110 (2), 360-367.
Drugan, R.C, Scher D.M, Sarabanchong, V., Guglielmi, A., Meng, I., Chang, J., Bloom, K., Sylvia S., Holmes, P. (1992). Controllability and Duration of Stress Alter Central Nervous System Depressant- Induced Sleep Time in Rats. Behavioral Neuroscience, 106 (4), 682-689.
National Institute of Mental Health. 2009. Anxiety Disorder Among Adults. Retrieved from <http://www.nimh.nih.gov/statistics/1ANYANX_ADULT.shtml>.
Robinson, J., Sareen, J., Cox, B.J, Bolton, J. 2009. Self-medication of anxiety disorders with alcohol and drugs: Results from a nationally representative sample. Journal of Anxiety Disorders, 23 (1), 38-45.
Warner, T.A., Lowry, C.A., Stafford., N.P., & Drugan, R.C. (2013). Intermittent swim stress effects on anxiety behavior. Program No. 128.18. Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2013. Online.
(Left) Each animal was trained on the rotarod prior to stress, and then again 2 hours post ISS. Motor ataxia was measured 12 min. post injection
Rotarod Criterion Test
Intermittent Swim Stress (ISS):
Ultrasonic Frequency Microphone
(Right) conditioner used to record ultrasonic vocalizations. The microphone was positioned just below the ISS
Effects of Alcohol and Ethanol on Motor Ataxia
All behavioral procedures were reviewed and approved by the University of New Hampshire Institutional Animal Care and Use Committee (IACUC).
This project was funded by a grant award provided by the Hamel Center for undergraduate research.
Special thanks to India Stribling and Nate Stafford for all of their help throughout this project.
Figure 1: The mean time (seconds) spent on the rotarod following ISS exposure and interperitoneal injection. Rotarod testing took place twelve minutes following injection.