PACAP Is Present in the Olfactory System and Evokes Calcium Transients in Olfactory Receptor Neurons

J Neurophysiol, 2003 · DOI: 10.1152/jn.00288.2003 · Published: October 1, 2003

Simple Explanation

This study investigates the presence and role of PACAP, a neuroregulatory peptide, in the olfactory system. PACAP is found in areas of the brain that generate new cells, including the olfactory bulb. The researchers found that PACAP is present in the olfactory epithelium of neonatal and adult mice and rats. They also discovered that PACAP is produced by olfactory ensheathing cells, which support the regeneration of olfactory neurons. Using calcium imaging, the study showed that olfactory receptor neurons respond to PACAP, suggesting that PACAP plays a role in the turnover, support, and protection of these neurons.

Study Duration

Not specified

Participants

Swiss Webster mice, Simonsen Albino rats, CD-1 mice

Evidence Level

Not specified

Key Findings

1
PACAP immunoreactivity is present in the olfactory epithelium of neonatal, adult mice, and adult rats.
2
PACAP expression pattern differs between neonatal and adult mice.
3
Olfactory ensheathing cells produce PACAP.

Research Summary

This study examines the expression and function of PACAP in the olfactory system of mice and rats, finding it present in olfactory epithelium and olfactory ensheathing cells. The study highlights differences in PACAP distribution between neonatal and adult mice, with neonates expressing PACAP mainly in OECs, while adults express it in ORNs and basal cells. Calcium imaging reveals that PACAP activates receptors on olfactory receptor neurons (ORNs), suggesting a role in neuronal-glial communication and the regenerative properties of the olfactory system.

Practical Implications

Neurotrophic Support

PACAP may provide neurotrophic support during development and regeneration of olfactory receptor neurons.

Neuroprotective Support

PACAP may offer neuroprotective support to mature olfactory receptor neurons.

Regeneration Mechanisms

PACAP may be an important peptide to consider when exploring the regeneration-promoting mechanisms of olfactory ensheathing cells.

Study Limitations

1
The exact mechanisms of PACAP action in olfactory receptor neurons remain unclear.
2
The study did not determine whether lack of Ca2+ responses reflects absence of receptor, lack of transduction machinery, state of Ca2+ stores, differences in developmental stages of the cells, or Ca2+-independant PACAP responses.
3
Desensitization of PACAP responses made it difficult to fully characterize the calcium signaling pathways involved.

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