Cannabis makes smelling cells fitter

New findings on the role of the body's own cannabis system in the nervous system

Overview of the front part of the brain and the nose of the larva of the African clawed frog Xenopus laevis. © cmpb
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The function of sensory cells in the nose is decisively influenced by cannabinoids. As Göttinger scientists have shown for the first time in animal experiments, the olfactory cells react to fragrances delayed, weak or not at all, if they were previously treated with a cannabis inhibitor. However, the recognition of the fragrances normalized as soon as cannabis was added and the antagonist's effect was abolished. The findings provide important information about the role of the body's own cannabis system in the nervous system.

The scientists around Professor Dr. Detlev Schild, dr. Dirk Czesnik and dr. Ivan Manzini, Department of Neurophysiology and Cell Biophysics of the University Medical Center Göttingen and the DFG Research Center for Molecular Physiology of the Brain (CMPB) conclude that endogenous substances that influence cannabis increase the sensitivity of at least some sensory systems. The findings were published in February in the online edition of the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Cannabis has been used medicinally by many peoples for millennia. But only since the late 1980s is it known that the human body itself produces cannabis-comparable substances - so-called endocannabinoids - and these substances play a role in signal processing in the brain. The potential impact of endocannabinoids in neurological and psychiatric disorders such as schizophrenia, multiple sclerosis or Parkinson's has been the subject of much research ever since.

It is known that regular consumption of cannabis can lead to long-term cognitive damage such as loss of motivation and concentration. But the basic mechanisms that take place at the molecular and cellular level in the brain are not yet clear.

Tadpoles as "guinea pigs"

The Göttingen researchers have now tested the influence of cannabinoids in a suitable model system - the sense of smell of tadpoles. The aim of the present study was to investigate the influence of the body's own cannabinoid system on smelling and to clarify its significance for sensory perception. display

For their investigations, the researchers changed the concentration of cannabinoids, while simultaneously stimulating the sensory cells. Depending on the presence or absence of cannabinoids, the electrical and chemical signals of the sensory cells varied widely. "For the first time, this proves that cannabinoids not only change signals in the brain, but also already affect those signals that are directed to the brain, " says the head of the study, Professor Detlev Schild.

"Many of the basic mechanisms of the olfactory system have been preserved in the course of evolution, so it is likely that cannabinoids could also act in the olfactory system of higher vertebrates and in humans, " explains Manzini, examining the tadpoles,

Too much cannabis leads to odor hallucinations

"That body's own cannabinoids influence odor perception makes sense, considering earlier studies that have shown increased cannabinoid levels in animals' brains when hungry Since it is known that one perceives odors more strongly when one is hungry, a correlation between the amount of the body's own cannabinoids and the olfactory sensibility is close, "says Czesnik:" The more cannabis works, the stronger the sense of smell, making it plausible that too much cannabis can lead to odor hallucinations. " However, the results also show that the body's own cannabinoids not only play a role in the central processing of stimuli in the brain, but also act very early in the periphery of perception.

(idw - DFG Research Center for Molecular Physiology of the Brain, 26.02.2007 - DLO)