Food odors have demonstrated influence on proteostasis (balance between formation and degradation of proteins), finds a study carried out in the roundworm Caenorhabditis elegans, a key model organism in biomedical research. Also, the study showed that out of 358 neurons that comprise of the nematode nervous system, two of them are part of the olfactory system that is significant for odor perception.
The smell of food induces a variety of physiological processes in our body. Thus, the production of saliva and digestive enzymes is stimulated before the actual food intake in order to prepare the gastrointestinal tract for the upcoming digestive process. In a healthy organism, this coordination depends on a dynamic balance between formation and degradation of proteins (proteostasis). This plays an important role for the recycling of cells and during the aging process.
‘Malfunctions in the perception of smell are associated with neurodegenerative diseases.’
The researchers were able to uncover the influence of smelling on the physiology of the digestive tract by investigating the recycling of green fluorescent proteins in the intestine. The brighter the green fluorescent signal within the worms, the more severe the accumulation of cellular waste, strongly correlating with defective protein degradation.
The underlying processes are mediated by the regulatory microRNA molecule mir-71. This molecule regulates the genetic program of olfactory neurons and, afterwards, degradation processes in the digestive tract. However, if this mechanism is blocked, not only are cellular recycling processes diminished, the animal's lifespan is also reduced. In other words, roundworms with a non-functional 'sense of smell' live much shorter - a strong indication for its physiological significance.
This mechanism is central for the proper processing of odor signals and mediates adjustments in the intestinal cells. 'We assume that the organism coordinates food intake and effective degradation this way', commented first author Dr. Fabian Finger, who was recently awarded with the Klaus Liebrecht Prize of the UoC for his work.
'The impact of odors at the cellular level is a poorly investigated field', says Thorsten Hoppe. 'It is well known that malfunctions in odor perception are associated with neurodegenerative diseases. We will further investigate the influence of the perception of odors on aging-associated disorders such as Alzheimer's or Parkinson's disease.'