The sense of smell regulates glioma formation through olfactory nerve functional circuits

Academician Duan Shumin of the Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, used previously constructed mouse models of endophytic glioma to confirm that the sense of smell can directly regulate the formation
of glioma.

In a mouse model, the researchers reproduced gliomas
that formed from oligodendrocyte precursor cells.

Gliomas first appear in the olfactory bulb, the first stop
of the brain's olfactory circuitry.

Within the olfactory bulb, controlling the activity of olfactory receptor neurons can affect the development of
gliomas.

The sense of smell stimulates the cap-like cells and clustered cells within the olfactory bulb, releasing insulin-like growth factor1
.

If Igf1 is specifically knocked out in M/T cells, glioma formation
can be inhibited.

In addition, knockout of IGF1 receptors in pretumor mutants eliminates the activity-dependent mitotic effects
of ORNs in OPCs.

It can be seen that the reception of olfactory and the formation of gliomas of the brain pass through the corresponding olfactory neuronal circuits
.

The results were published online in Nature in
May 2022.

—Excerpted from the article chapter

【Ref: Chen P, et al.
Nature.
2022 Jun; 606(7914):550-556.
doi: 10.
1038/s41586-022-04719-9.
Epub 2022 May 11.
】

Research background

Animals are constantly exposed to various sensory stimuli from their surroundings, such as smells, sounds, light, and touch
.

Through sensory input, it is essential for animals to find food and avoid predators, but sensory stimulation also affects the physiological state of the organism and can lead to diseases such as cancer
.

Malignant gliomas are the deadliest brain tumors and are closely linked
to neurons at the cellular level.

However, it is unclear
whether external sensory stimulation can directly affect the development of malignant glioma under normal living conditions.

Academician Duan Shumin of the Department of Neurosurgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, used previously constructed mouse models of endophytic glioma to confirm that the sense of smell can directly regulate the formation
of glioma.

In a mouse model, the researchers reproduced gliomas
that originated from oligodendrocyte precursor cells (OPCs).

Gliomas first appear in the olfactory bulb, the first stop
of the brain's olfactory circuitry.

Within the olfactory bulb, controlling the activity of olfactory receptor neurons (ORNs) can affect the development of
gliomas.

The sense of smell stimulates the monk cap cells and clustered cells (mitral/tufted, M/T) in the olfactory bulb, releasing insulin-like growth factor 1 (IGF1).


If Igf1 is specifically knocked out in M/T cells, glioma formation
can be inhibited.

In addition, knockout of IGF1 receptors in pretumor mutants eliminates the activity-dependent mitotic effects
of ORNs in OPCs.

It can be seen that the reception of olfactory and the formation of gliomas of the brain pass through the corresponding olfactory neuronal circuits
.

The results were published online in Nature in
May 2022.

Conclusion of the study

This study is the first to intervene in gliomagenesis by physical means, revealing that the stimulation of the olfactory organ by external odor can directly affect the occurrence
of glioma.

The olfactory bulb stimulates the monk cap cells and clustered cells, releases IGF1 to regulate the growth of glioma, and verifies the important position
of olfactory nerve functional circuits in gliomagenesis.