Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Parkinson's disease involves degeneration of the olfactory system

28.09.2017

Scientists discover anatomical link for the loss of smell in Parkinson’s disease

The first symptom of Parkinson's disease is often an impaired sense of smell. This neurodegenerative disease primarily causes irreparable damage to nerve cells in a brain area involved in movement control. How it affects the olfactory system has been unclear.


Lewy bodies and Lewy neurites are filled with misfolded alpha-synuclein and are hallmark pathologies of brain tissue in Parkinson's disease. The nuclei of olfactory bulb cells are visualized with a blue-fluorescent dye. The abnormal alpha-synuclein is visualized in red fluorescence by staining with a specific antibody.

© Max Planck Research Unit for Neurogenetics


Ventral view of glomeruli in a human olfactory bulb. Single glomeruli are represented in confetti-like colours.

© Max Planck Research Unit for Neurogenetics

Researchers at the Max Planck Research Unit for Neurogenetics in Frankfurt and the University of Auckland in New Zealand have now carried out a study comparing the olfactory bulbs of individuals with and without Parkinson’s disease. The researchers found that the total volume occupied by the functional units in the olfactory bulb – the so-called glomeruli – is in Parkinson's cases only half that in normal individuals. Moreover, the distribution of the glomeruli within the olfactory bulb is altered in Parkinson's cases.

Nine out of ten patients with Parkinson’s disease suffer from defects of the sense of smell in the early stages of the disease - often years before the appearance of the motor symptoms that are characteristic of the disease. The motor symptoms are caused by a loss of nerve cells in the region of the substantia nigra in the brain that is responsible for controlling movement.

What causes this cell death has not yet been fully clarified, but a key role appears to be played by Lewy bodies. These are inclusions, inside the cells, that contain a misfolded, defective version of the alpha-synuclein protein. Lewy bodies are found in the olfactory bulb before they appear in the substantia nigra.

The so-called olfactory vector hypothesis for Parkinson's disease proposes that environmental factors, such as viruses, heavy metals or pesticides, are risk factors or even causes of the condition.

No other sensory system than the olfactory system is in such close contact with the external environment - the inhaled air. The hypothesis posits that the disease-causing agent is introduced from the nasal cavity into the olfactory bulb, where Parkinson’s disease is triggered and gradually spreads through other parts of the brain.

Intact tissue samples required

The human olfactory bulb remains poorly studied. Research on this brain structure depends critically on the availability of pristine samples, which are typically procured post mortem, from brain donors. The Neurological Foundation of New Zealand Douglas Human Brain Bank in Auckland, New Zealand works closely with families of patients suffering from neurodegenerative diseases to ensure ethical and effective collection of post mortem brain samples from diseased and non-diseased cases.

The precarious location of the olfactory bulb below the bulk of the brain and the many axons that connect it to the olfactory mucosa mean that special efforts must be made to protect the morphology of the olfactory bulb when collecting the samples.

The New Zealand-based researchers were able to collect olfactory bulbs fit for an in-depth quantitative study. In a globe-spanning project, the researchers processed the post mortem olfactory bulbs chemically, cut ten-micrometer thin sections throughout its entire length, and stained the sections with fluorescently labeled antibodies. The labeled sections were then scanned in Frankfurt, and the images reconstructed in 3D allowing for quantitative whole-olfactory bulb analyses.

New quantitive parameter

As glomeruli of the human olfactory bulb are difficult to count unambiguously, the researchers came up with a new, quantitative parameter: the global glomerular voxel volume. This quantity is the sum of the volume of all glomeruli. These are formed by the coalescence of axons of olfactory sensory neurons making synapses with olfactory bulb neurons.

Having defined this new parameter, the researchers compared the values between olfactory bulbs from normal and Parkinson's disease cases, and found that it was reduced by more than half. Whether the decrease is the result of Parkinson’s disease cases having fewer or smaller glomeruli, or is due to a combination of these two effects, remains to be seen.

In addition, the distribution of the glomeruli was altered. The olfactory bulbs of normal cases had 70 percent of their glomerular component in the bottom half of the olfactory bulb, but the olfactory bulbs of Parkinson’s disease cases contained only 44 percent in the bottom half.

“The preferential deficit of the glomerular component in the bottom half of the olfactory bulb, close to the olfactory mucosa, is consistent with the olfactory vector hypothesis of Parkinson's disease”, states Peter Mombaerts, M.D., Ph.D., director of the Max Planck Research Unit for Neurogenetics. The scientists also discovered that the greater the number of Lewy bodies with aggregated alpha synuclein, the smaller the glomerular component of the olfactory bulb. “This relationship could be an indication that the Lewy bodies are the cause of the reduction in glomerular volume,” explains Dr. Bolek Zapiec, first author of the paper.

The question now is which type of neurons in the olfactory bulb is affected first or foremost in Parkinson's disease. Next the researchers would like to identify the neurons in the olfactory bulb that are the most vulnerable.


Contact
Peter Mombaerts, M.D., Ph.D.
Max Planck Research Unit for Neurogenetics, Frankfurt am Main
Phone: +49 69 850033-4000
Email: peter.mombaerts@gen.mpg.de

Original publication
Bolek Zapiec, Birger V. Dieriks, Sheryl Tan, Richard L. M. Faull, Peter Mombaerts, Maurice A. Curtis

A ventral glomerular deficit in Parkinson’s disease revealed by whole olfactory bulb reconstruction.

Brain; 3 September, 2017

https://dx.doi.org/10.1093/brain/awx208

Peter Mombaerts, M.D., Ph.D. | Max Planck Research Unit for Neurogenetics, Frankfurt am Main
Further information:
https://www.mpg.de/11484476/parkinson-olfactory-system

More articles from Health and Medicine:

nachricht Cancer cells make blood vessels drug resistant during chemotherapy
02.07.2020 | Hokkaido University

nachricht Novel potassium channel activator which acts as a potential anticonvulsant discovered
02.07.2020 | The Mount Sinai Hospital / Mount Sinai School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

Im Focus: AI monitoring of laser welding processes - X-ray vision and eavesdropping ensure quality

With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.

Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

 
Latest News

Rising water temperatures could endanger the mating of many fish species

03.07.2020 | Life Sciences

Risk of infection with COVID-19 from singing: First results of aerosol study with the Bavarian Radio Chorus

03.07.2020 | Studies and Analyses

Efficient, Economical and Aesthetic: Researchers Build Electrodes from Leaves

03.07.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>