If someone were to mention lab rats to you, what would you think of? You might recall the tissue engineering experiment a few years ago that gave us a rat with a real human ear growing on its backside, or perhaps the more memorable Pinky and the Brain come to mind, but what about psychedelic drugs?
Lab rats have helped us in leaps and bounds in research for medicine and psychology and they are at it again, this time with the help of SCCC Professor Mitch Harding, working towards a new breakthrough in depression treatment using the taboo drug, salvia divinorum.
Mitch is currently attending graduate school at UMSL, working towards his PHD in the Behavioral Neuroscience Program, on top of teaching Psychology here at SCCC. For the last four years has been doing research on laboratory rats for the benefit of science. His interest in salvia began when he read up on a case study from a psychiatrist in Australia who successfully treated a patient with intractable depression with salvia after all other standard treatments had failed. Unfortunately, salvia became illegal there and the study was unable to go any further, so Mitch decided he wanted to test these results on depressed rats.
How do you depress a rat, you ask? The same way you depress humans: you put them in stressful environments for prolonged periods of time. Mitch explains, "Kind of like how a crummy job or traffic would depress you over time, it's the same way with the rats, except we don't give them jobs or traffic. We do things like tilting their cage at a 45 degree angle, or put a strobe light on them over night, or blast them with unpredictable noises. What seems to me the most stressful thing we do is deprive them of water for a period of time, and then tease them with an empty water bottle after the deprivation."
While these may sound a bit extreme, they are only perceived to the rats as mild stressors; anything more extreme than these would be too much for the experiment.
Over a course of a few weeks, the rats unsurprisingly develop depression. This is made apparent by observing a symptom of depression, anhedonia, or the inability to experience pleasure from normally pleasurable things. This can easily be measured in rats by giving them two water bottles, one with regular water and another with sugar water. A normal, healthy rat will prefer the sugar water over the other water because of its sweeter taste. In fact, at the beginning of the study, a rat drank 90% sugar water over a 24 hour period. After the mild stressors, however, the preference between water bottles drop to about 50/50, a clear indicator that the rats were now depressed.
This is when things get interesting. At week four of the experiment, some rats were given salvia injections each day in the morning, and the others were given a placebo as a control. After about three weeks, while the rats that were given the placebo remained at the 50/50 level, the rats that were given salvia actually increased their sugar water consumption almost all the way back up to 90%, These results fully supported the results of the Australian experiment, concluding that salvia does indeed have anti-depressant properties.
What makes this an important revelation is that the chemicals found in salvia target a different part of the brain than usual when treating depression. Most of the anti-depressants today work on the serotonin receptor, the part of the brain related to mood, but salvia works on the opioid receptors, which deals with pain relief in the body. While we probably will not be giving people with depression salvia, in fact Mitch made it clear that giving depressed people hallucinogens is probably not the best idea in the world, this could mean huge opportunities for research for new types of medicine that target this part of the brain that was once believed to have no involvement in mood.
March 1, 2010
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Tales of a Depressed UMSL lab rat and Salvia