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Max Planck researchers have succeeded in showing in
experiments on mice that the anxiolytic substance neuropeptide S (NPS)
can be absorbed through the nasal mucosa and unfold its effect in the
brain. Having bound to its receptors, the neuropeptide S reaches
particular neurons in the brain in this way.
Just four hours after the administration of the drug, the tested mice
showed less anxiety. Altered neuronal activity was also measured
directly in the hippocampus, an important brain structure for learning
and memory. These findings confirm that neuropeptide S is a promising
new drug for the treatment of patients suffering from anxiety disorders.
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Medications that target the brain must overcome numerous hurdles, as it
is a very difficult organ for drugs to access. For example, if a patient
takes a pill, the drug must make its way through the digestive system,
the liver and the blood-brain barrier. This often gives rise to
undesired side effects.
In addition, a lot of the necessary active substance is lost or it is
altered in some way, or completely destroyed. The recently discovered
anxiolytic neuropeptide S (NPS) would not be able to reach the brain in
this manner. Treatment with this substance would only be conceivable by
injection into the brain, a process that patients could not be expected
to endure. Therefore, Ulrike Schmidt’s research group at the Max Planck
Institute of Psychiatry examined, with the aid of mice, whether NPS
could be absorbed into the brain through the nasal mucosa and take
effect there.
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In a series of sophisticated experiments, the scientists succeeded in
visualising the path taken by intranasally administered NPS to special
neurons in different regions of the brain. With this non-invasive method
of administration, the targeted and highly specific absorption of the
substance in the brain cells takes place through the binding of the
substance to the NPS receptor.
Just 30 minutes after administration through the nasal mucosa, small
volumes of NPS had reached the mice brains. The anxiolytic effect
unfolded four hours later: it could be observed that the mice had
actually become less anxious. It was thus possible to demonstrate the
anxiolytic effect of neuropeptide S when administered intranasally. The
exact molecular mechanism of action of NPS is still unclear.
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However, as electrophysiological tests have shown, it clearly influences
the signal transmission pathways between the neurons of the hippocampus.
The researchers suspect that NPS has an attenuating effect on certain
signals of the brain’s emotion centre and less anxiety is perceived as a
result.
“Our findings open the door to the development of new drugs based on
neuropeptide S for patients suffering from pathological anxiety,” says
psychiatrist Ulrike Schmidt. “The simple administration and the fast and
successful effect of an anxiolytic nose spray could be a real blessing
for many patients who suffer from anxiety disorders like panic attacks
and post-traumatic stress disorders.”
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