May 09, 2002
NEW YORK (Reuters Health)
Intranasally administered insulin and melanocortin (4-10) quickly accumulate in cerebrospinal fluid (CSF) without affecting blood levels, while intranasal vasopressin enters the bloodstream at the same time it enters the CSF, investigators report in the advance online publication of Nature Neuroscience for May 6th.
Dr. Jan Born, of the University of L beck in Germany, and colleagues measured CSF and blood levels of the three peptides after administering them to healthy adult volunteers. Concentrations in the CSF began to rise within 10 minutes of administration.
Melanocortin (4-10) and insulin reached peak levels within 30 minutes, while vasopressin continued to rise for up to 80 minutes. Concentrations remained above control levels at the end of the 80-minute sampling period.
There was no corresponding significant increase in blood levels of insulin and melanocortin (4-10), while vasopressin serum levels rose in proportion to CSF levels.
The authors hypothesize that peptide molecules pass through patent intercellular clefts in the nasal epithelium to diffuse into the subarachnoid space. The result is that compounds that cannot readily traverse the blood-brain barrier when administered intravenously can reach therapeutic levels in the CNS, often without exerting strong, systemic hormone-like side effects.
Dr. Born's group hopes that nasal drug delivery will be useful in the treatment of diseases that involve dysfunctional neuropeptide signaling, such as Alzheimer's disease and obesity.
© 2002 Reuters Ltd