Characterization of Thermoregulatory Efferents to the Paraventricular Nucleus of the Rat Hypothalamus

The paraventricular nucleus of the hypothalamus (PVN) is the gatekeeper to temperaturemodulating hormones such as vasopressin. Indeed, it is in theory a key target region for thermoregulatory efferents of the preoptic area of the anterior hypothalamus (POAH). Although several retrograde labeling studies have identified a connection between the POAH and PVN, none have directly characterized the thermoregulatory nature of this interaction. We will identify the phenotype of these connections by injecting retrograde-labeling nanoprobes into the PVN of live tissue slices and quantified labeled POAH somas. These probes are designed for selective uptake by glutamate-releasing axon terminals, after which they diffuse rapidly to the neuron soma. Our results indicate that glutamatergic neurons do project from the POAH to the PVN. This technique will allow for further electrophysiologic studies to identify the thermosensitivity of neurons with a known connectivity and phenotype.