Intranasal peptide delivery
Nose-to-brain is an enticing phrase. I wanted the journey through nasal tissue and brain to come into focus.
The shortcut I expected
The attraction is easy to picture: the nose sits close to the brain, so perhaps delivery through it offers a more direct way in. I pursued that possibility through the intranasal work. The papers gathered here, though, mostly show what happened afterwards: altered gene expression, a protein change, improved movement.
The Semax regional study measures NGF and BDNF messenger RNA after nasal administration in rats. The Selank hippocampal paper in rats examines BDNF expression after the same broad route. I cannot reconstruct a molecule's exact passage through nasal and brain tissue from those downstream changes alone. The shortcut I pictured gave way to a set of much more specific questions.
Brain regions and measured outcomes
Semax supplies the clearest reason to care about destinations. In rats, its regional RNA results include both increases and a decrease, while a separate BDNF-protein experiment, also in rats, reports an increase in the basal forebrain and none in the cerebellum. A single claim that a peptide raises BDNF would hide the region, measurement and experiment.
DSIP's intranasal stroke study in rats follows function: motor recovery improved by day seven, with a statistically insignificant infarct-volume difference. That gives the delivery discussion a behavioural result, alongside the molecular ones. It still leaves the exact route to the effect unresolved.
Other administration routes
Several papers nearby ask different questions using different routes. The small DSIP insomnia trial used intravenous administration. The original rabbit experiment infused DSIP into the brain. The engineered DSIP fusion in mice changes the molecule itself in an attempt to address the blood-brain barrier, the selective boundary between blood and brain tissue.
A study of the relevant preparation, route and outcome in people would be needed to connect those results to a human nasal sleep treatment. None of these papers provides that entire connection.
Nasal tissue and solution quality
In community discussions of intranasal Semax and Selank, people report burning, dryness, stinging, sneezing or congestion. These are anecdotal accounts rather than clinical evidence. The entrance has tissue of its own. For me, the nasal lining deserves as much attention as the destination.
Research-grade solutions also leave uncertainties about identity, purity and sterility. The nasal route does not resolve those uncertainties. Persistent sleep or anxiety symptoms require medical assessment; the delivery literature cannot perform that assessment.
The compound comparison returns to the individual experiments. For the most detailed regional pattern, start with Semax.