Getting tadpoles stoned helps them see in the dark, according to a study that appeared recently in the journal eLife. And while scientists don’t yet have any evidence that smoking weed can improve the night vision of humans, the results of this research suggest that this could well be the case.
Marijuana contains compounds like THC that bind to the cannabinoid receptors in the brain in order to produce a range of effects. Among these is a receptor known as CB1, which controls several of the sensations typically associated with being stoned. Interestingly, the human retina contains a high concentration of CB1 receptors, suggesting that cannabis probably has an effect on our vision.
To investigate, the study authors applied synthetic cannabinoids to the eye tissue of tadpoles of the African clawed toad, and used tiny electrodes to measure how this influenced the activity of their retinal neurons – known as retinal ganglion cells (RGCs). Readings indicated a spike in RGC activity in the presence of cannabinoids, suggesting that activating CB1 receptors increases the sensitivity of these light-detecting cells.
To confirm this, the team then placed the tadpoles in a petri dish along with some black dots that were designed to look like predators, so that the tadpoles would consciously avoid them. In low light conditions, tadpoles that had received cannabinoids were much better at dodging these dots than those that hadn’t been treated with the drug, indicating that their RGCs had become more sensitive to light, allowing them to see better in the dark.
In their write-up, the researchers explain that the binding of these cannabinoids to the CB1 receptors in the tadpoles’ retinas resulted in the inhibition of a protein called NKCC1, which transports chloride, potassium and sodium ions across neuronal membranes.
Blocking the activity of this transporter leads to a decrease in the number of negatively charged chloride ions inside neurons, which causes membranes to become hyperpolarized, resulting in an increase in electrical activity.
Though more research is required in order to confirm if cannabis produces the same effect in humans, the findings of this study certainly provide some interesting food for thought as the scientific community continues to probe the drug’s medicinal properties.