Chronically Smoking Rats

 Smoking cigarettes is generally accepted as being bad for us and there are lots of studies around second-hand smoking, though the term “passive” is probably a better descriptor. There are a large number of conditions that are a problem due to cigarette smoke in addition to heart and lungs.

Apparently it appears to be a factor in the development of Alzheimer’s and dementia. There appears to be some evidence for it being a risk factor for cognitive decline in that it may enhance the rate of decline. Ho et al decided to tackle this from the neuropathology angle to get a measure of the chemical and structural changes that can occur in the brain of chronic smokers. Their results are published in the Public Library of Science (1).

The chronic (passive) smokers in this case were 5 rats who jointly (so to speak) were consuming 12 cigarettes in a one-hour session held every day for 56 days. The preferred smoke was filter tip Camels, but like most passive smokers, they didn’t get a choice of brand. There were also 4 rats who ran around in nice clean air for that same hour and were the control group.

There was no cognitive testing of our rodent friends, but each one had its brain examined. In a great deal of detail, I should add. The results were quite clear with signs of oxidative stress in the hippocampus of the smokers as well as a decrease in pre-synaptic proteins.

This is bad news as we all want our synapses to give us increasing connectivity. The spikyness of the neurons was also decreased. These two things look like a decrease in plasticity, that is a sign of cognitive decline. Other proteins were also affected. All in all the synaptic decline was indicating the path of a neurodegenerative  condition.

There was no sign of senile plaque and the authors point out that smoking is only one risk factor for Alzheimer’s. Anyway 56 days for chronically smoking rats is quite a short time.

I feel compelled to wonder if, after that short time, were they hooked? And given the choice, would they have opted for a patch or chosen to go cold turkey if the dangers of signing up for this experiment had been explained to them?


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