University of Louisville
Epithelial Overexpression of BDNF Affects Different Neuron Types in Distinct Ways
Abstract
Taste bud cells detect information about the chemical composition of our food, and this information is carried to the brain by peripheral taste neurons. How the peripheral taste system is organized during development is still unclear. It is possible that peripheral taste neurons exist as a single neuron type such that all peripheral neurons are influenced by the same developmental factors. Alternatively, taste neurons could be divided into types or parallel pathways that are differentially influenced by developmental factors. To distinguish between these possibilities, we focused on Brain-derived neurotrophic factor (BDNF). BDNF is a regulator for taste neuron development and is an essential component in the survival and targeting of geniculate ganglion neurons. When BDNF is overexpressed (BDNF-OE) throughout the tongue epithelium, there is an increase in the total number of geniculate neurons, because neurons were rescued from cell death. However, there is a decrease in the total number of innervated taste buds because targeting was disrupted. These effects were described for the entire population of taste neurons, which we now know expresses multiple genetic markers indicating they could be different types. To determine if BDNF-OE distinctly impacts different neuron types, I examined one neuron type defined in the taste system Proenkephalin (Penk) expression compared to the full population defined by the expression of the transcription factor, Phox2b, in adult BDNF-OE mice and control mice. We found that mice overexpressing BDNF in the lingual epithelia had fewer Penk+ taste neurons compared to wild-type mice. While the total population of Phox2b+ taste neurons remained unaffected in BDNF-OE mice, Penk+ neurons decreased in BDNF-OE mice compared to control mice (p
Epithelial Overexpression of BDNF Affects Different Neuron Types in Distinct Ways
Taste bud cells detect information about the chemical composition of our food, and this information is carried to the brain by peripheral taste neurons. How the peripheral taste system is organized during development is still unclear. It is possible that peripheral taste neurons exist as a single neuron type such that all peripheral neurons are influenced by the same developmental factors. Alternatively, taste neurons could be divided into types or parallel pathways that are differentially influenced by developmental factors. To distinguish between these possibilities, we focused on Brain-derived neurotrophic factor (BDNF). BDNF is a regulator for taste neuron development and is an essential component in the survival and targeting of geniculate ganglion neurons. When BDNF is overexpressed (BDNF-OE) throughout the tongue epithelium, there is an increase in the total number of geniculate neurons, because neurons were rescued from cell death. However, there is a decrease in the total number of innervated taste buds because targeting was disrupted. These effects were described for the entire population of taste neurons, which we now know expresses multiple genetic markers indicating they could be different types. To determine if BDNF-OE distinctly impacts different neuron types, I examined one neuron type defined in the taste system Proenkephalin (Penk) expression compared to the full population defined by the expression of the transcription factor, Phox2b, in adult BDNF-OE mice and control mice. We found that mice overexpressing BDNF in the lingual epithelia had fewer Penk+ taste neurons compared to wild-type mice. While the total population of Phox2b+ taste neurons remained unaffected in BDNF-OE mice, Penk+ neurons decreased in BDNF-OE mice compared to control mice (p