The project's overall objective is to study afferent nociceptor activity in the corneas of transgenic
mice as a novel method for studying oral cancer pain. Using a scanning laser confocal for Ca2+
imaging in vivo, we will assess the change in fluorescence of Ca-reporter GCaMP3 expressing
sensory neurons in response to a known algesic stimulus (10-100 μM capsaicin). This activity
will be compared to that from supernatants of cultures of oral cancer cells. The supernatant will
be obtained from our colleague, Dr. Brian Schmidt. The experiments will also involve the use of
a corneal recording chamber (engineered by our mentor, Dr. Stephen Roper) and a
microperfusion "picospritzer" system. Many issues still exist in terms of optimal protocol. One
obstacle is to stabilize the mouse during experiments without changing the neuron's response to
capsaicin. Nerve fibers in the eye must remain stable, within a few microns, over multiple trials
in order to be able to analyze the data. Another issue is how to control the currents of the tyrode
bath around the eye that impacts capsaicin perfusion. There is an inflow and outflow system
that washes away the capsaicin, causing turbulence even within the short micron distance
between the picospritzer and the cornea. This research will help to develop optimal dosage and
imaging protocols for studying corneal nociceptor activity and analyzing neural responses to
capsaicin.
