Stress has been a hot topic lately. In the past week, we’ve looked at how chronic stress can trigger working memory deficits among the poor and lead, eventually, to severe depression. But there’s hope, at least if you’re a stressed out lab rat. (In theory, these findings should apply to humans, but there’s always that nagging gap between theory and reality.) The work is led by Robert Sapolsky, the incredibly engaging and eloquent primatologist and writer.
The experimental strategy strategy is ingenious. The scientists begin by inserting “neuroprotectant” genes, such as estrogen, into a modified version of herpes simplex virus. Why herpes? For starters, the virus is able to quietly enter nerve cells. Ordinarily, this viral invasion would lead to an acute infection and cell death. But Sapolsky and his team have engineered the virus so that it can’t multiply and commandeer the cell. Instead, it just lurks in the nucleus, waiting to be turned on and express these protective snippets of DNA.,
Here’s where the idea really gets brilliant. It’s been known for some time that many viruses, like herpes, wait until our stress hormones are elevated before they become active and multiply. This increases the chances that the viral infection will defeat, at least for a few days, the defensive efforts of our immune system, since stress suppresses the immune response. In other words, when the rat is happy and relaxed, everything is normal – the virus and its estrogen genes are utterly inactive.
But now let’s say something stressful happens. Perhaps the rat is subjected to some fear conditioning, or maybe a cerebral artery is ruptured and the brain is deprived of oxygen. At this point, the herpes virus senses the elevated stress hormones and switches into action. Within hours, it’s able to start generating neuroprotective proteins which, at least in the rat, seem to limit the extent of cell death and damage. The carnage remains local. According to some preliminary experiments, rats given the herpes treatment were able to stave off practically all cell loss, while control rats lost nearly 40 percent of neurons in a given region.
At the moment, of course, such a stress vaccine remains entirely hypothetical, at least for humans. (And this is one of those treatments that I definitely want medicine to perfect before clinical trials begin. It wouldn’t be fun to have errant herpes viruses rampaging through the cortex, pumping out estrogen for no good reason.) But I think there’s good reason to hope that, someday, we might be able to design treatments which eliminate the most devastating parts of the chronic stress response. This vaccine won’t guarantee happiness, or protect against acute stress, but it just might let us outsmart the worst parts of the fight or flight response.
Thanks to Arielle for the tip!