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Spectrum: Autism Research News

Delivered in vapor, oxytocin slips past brain’s barrier

by  /  25 June 2014
THIS ARTICLE IS MORE THAN FIVE YEARS OLD

This article is more than five years old. Autism research — and science in general — is constantly evolving, so older articles may contain information or theories that have been reevaluated since their original publication date.

Deep sniff: Researchers have used nasal sprays to study oxytocin’s effects, but a mask and aerosol combination may be a better option for children.

A fine, inhaled mist may be the most effective way to deliver oxytocin — a hormone involved in social bonding — to the brain, reports a study on monkeys published 3 March in Psychoneuroendocrinology1. If oxytocin proves to be an effective drug for disorders such as autism, this method may be the best way to give it to children.

Oxytocin’s role in social behaviors has piqued the interest of autism researchers, but the hormone’s effectiveness as a drug is still under debate. For example, two small studies published this year showed that inhaling doses of the hormone helps people with autism recognize others’ emotions. However, another study found no benefit.

Part of the problem may be the difficulty in getting oxytocin into the brain. A barrier of specialized cells protects the brain from any pathogens or toxins circulating in the blood. Oxytocin is too large to cross this blood-brain barrier easily.

Nasal sprays have seen some success, perhaps because a small amount of the hormone slips through gaps in the barrier in the nasal passage. The sprays require skill to administer correctly, however: The inhaler must hold one nostril closed, pump a specific number of sprays into the other and sniff deeply, instructions that are difficult for children and some adults with autism to follow.

The new study tested the effectiveness of nasal sprays, injections and an aerosolized spray in delivering oxytocin into the brain and spinal fluid of rhesus macaque monkeys. Aerosolized oxytocin, administered through a mask that covered a monkey’s nose and mouth, boosts levels of the hormone two- to three-fold in the spinal fluid. Oxytocin injections and nasal spray do not have this effect, the researchers found.

Unlike nasal sprays, the new method does not depend on the participant’s ability to sniff, and delivers a more consistent dose of oxytocin to everyone, the researchers say.

References:

1. Modi M.E. et al. Psychoneuroendocrinology 45, 49-57 (2014) PubMed


TAGS:   autism, oxytocin