Presentation Title

Neonatal Chorda Tympani Transection Reduces NaCl Responses in the Glossopharyngeal Nerve of the Adult Rat

Advisor Information

Suzanne Sollars

Location

UNO Criss Library, Room 231

Presentation Type

Oral Presentation

Start Date

7-3-2014 3:30 PM

End Date

7-3-2014 3:45 PM

Abstract

Injury to the peripheral taste system of the rat produces more severe changes to the system if the damage occurs during development. Transecting – or cutting – the chorda tympani (CT) nerve (which relays taste information from the anterior tongue to the brain) leads to several structural, functional, and behavioral differences in the taste system. In adult rats, these changes are short-lived; the CT regenerates in about 45 days, and an almost complete recovery is observed. When CT transection (CTX) occurs in neonatal (or pre-weaning) rats, the CT fails to regenerate and consequently, injury-induces changes are permanent. Interestingly, neonatal, but not adult CTX leads to an abnormal preference for ammonium chloride (NH4Cl) – a salt that intact rats never prefer. In order to determine if changes in taste nerve functioning could account for this NH4Cl preference, whole-nerve electrophysiology was performed on another taste nerve - the glossopharyngeal (GL). Rats either received neonatal CTX or a control surgery, and at least 50 days later, GL responses to taste stimuli were recorded. GL activity following NaCl stimulation was lower in rats receiving CTX compared to controls. This result suggests that the way NaCl is detected and converted into a neural code is altered after early injury to the CT. No changes in nerve response to NH4Cl stimulation were found, indicating that altered GL activity is not responsible for creating a preference for that stimulus. Work is currently underway to determine the mechanism responsible for altering GL functioning after neonatal CTX.

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Mar 7th, 3:30 PM Mar 7th, 3:45 PM

Neonatal Chorda Tympani Transection Reduces NaCl Responses in the Glossopharyngeal Nerve of the Adult Rat

UNO Criss Library, Room 231

Injury to the peripheral taste system of the rat produces more severe changes to the system if the damage occurs during development. Transecting – or cutting – the chorda tympani (CT) nerve (which relays taste information from the anterior tongue to the brain) leads to several structural, functional, and behavioral differences in the taste system. In adult rats, these changes are short-lived; the CT regenerates in about 45 days, and an almost complete recovery is observed. When CT transection (CTX) occurs in neonatal (or pre-weaning) rats, the CT fails to regenerate and consequently, injury-induces changes are permanent. Interestingly, neonatal, but not adult CTX leads to an abnormal preference for ammonium chloride (NH4Cl) – a salt that intact rats never prefer. In order to determine if changes in taste nerve functioning could account for this NH4Cl preference, whole-nerve electrophysiology was performed on another taste nerve - the glossopharyngeal (GL). Rats either received neonatal CTX or a control surgery, and at least 50 days later, GL responses to taste stimuli were recorded. GL activity following NaCl stimulation was lower in rats receiving CTX compared to controls. This result suggests that the way NaCl is detected and converted into a neural code is altered after early injury to the CT. No changes in nerve response to NH4Cl stimulation were found, indicating that altered GL activity is not responsible for creating a preference for that stimulus. Work is currently underway to determine the mechanism responsible for altering GL functioning after neonatal CTX.