What Do You Call A Rat With A Cold?

Rat-achoo-ouille!

Rats have one of the best senses of smell in the world and this is all thanks to their olfactory system. In Duke University, a group of scientist were able to produce images of the brain detecting specific smell molecules. According to the paper, “Since deoxyhemoglobin absorbs red light more than the oxygenated form, the scientists could distinguish activated glomeruli by imaging the olfactory bulbs under a red light shone through the rat's skull. Activated glomeruli showed up as distinctive dark spots on the images” (Duke University, 1999). This indicates the odor molecule triggers the olfactory bulbs, which sends it up to the brain to distinguish. The odor travels through the nasal cavity where it reaches the olfactory region. In the region, olfactory receptors are triggered and it sends signals to the brain (Alvites et al., 2018). This is how rats are able to detect the smell of food, attraction or predators from a long distance. To attract male rates, they release an odor, muscone, which signals MOR215–1 and MOR214–3 that trigger the brain for attraction (Horio, 2019). The presentation of predator odors increases in the stress hormones, corticosterone and adrenocorticotropin (ACTH), defensive behavioral responses, and autonomic nervous system activation (Cher et al., 2009). In an experiment, Male Sprague-Dawley rats were treated with 10% zinc sulfate which made them lose their sense of smell. They were unable to detect the difference between strawberries and ferret (rat predator) and stress hormones were not released (Cher et al., 2009). This shows that the olfactory system is very important in their survival and hunting. They also have a vast variety of olfactory receptors with scientists being able to detect 1,493 genes as OR genes, although most of these were pseudogenes (Quignon et al., 2005).