Individual nerve cells in the hippocampus have absorbed the Neuropeptide S, which was previously coloured with a red dye. The cell nucleii are blue and the axons are coloured green. Max Planck Institute of Psychiatry |
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.
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.
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. 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.”
