Stress-Related Effects of Phoenixin on Nucleus of the Solitary Tract Neurons

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Grover, Hanna
Stress , Electrophysiology , Phoenixin , Nucleus of the Solitary Tract
Phoenixin (PNX) is a recently discovered neuropeptide that was initially determined to positively contribute to reproductive functioning. Since its discovery, however, PNX has been implicated in a diverse range of physiological activity, including anxiety-like behavior, nociception, memory retention, and food intake. With a robust pattern of expression to compliment these physiological actions, it is clear that PNX plays a pleiotropic role. The nucleus of the solitary tract (NTS), a critical autonomic integrating center in the hindbrain, is one of the many areas with dense expression of both PNX and its receptor, GPR173. Using both extracellular and whole-cell current clamp recording techniques in a coronal NTS slice preparation, this study characterized the effects of PNX on both spike frequency and membrane potential of NTS neurons in order to determine neuronal effects of the peptide. Extracellular recordings demonstrated that PNX increased firing frequency in 32% of male rat NTS neurons, and patch clamp recordings indicated that this effect also existed for membrane potential, with 50% of NTS neurons depolarizing in response to application of the peptide. Our study took an abrupt turn when total responsiveness to PNX in NTS neurons declined suddenly to 9%. This effect was subsequently attributed to construction in our laboratory facility after rats were relocated to a construction-free facility and PNX responsiveness was recovered. Rats were then placed on a corticosterone (CORT)-stressor treatment that replicated the decreased PNX responsiveness within 2 weeks and had no effect on the responsiveness of neurons to another neuropeptide, Angiotensin II (ANG). These results implicate PNX in the central integration of stress and potentially provide new insight into a factor of stress-related infertility.
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