Obesity is often associated with multiple other clinical conditions, including hypertension and cardiovascular disease. Currently, more than one-third of the world’s population is classified as obese. Leptin is a neuropeptide that is released from adipose cells and is responsible for reducing appetite and increasing metabolism. Leptin also has a role in the activation of cardiovascular and metabolic pre-sympathetic neurons and has been reported to increase blood pressure and heart rate. Thus, understanding the activation of the autonomic nervous system by leptin has implications in the development and safety of drugs to avoid activation of cardiovascular pre-sympathetic neurons. This is important because a drug that causes an increase in blood pressure or heart rate would not be effective in diminishing cardiovascular-related comorbidities. This study tests the hypothesis that intracerebroventricular leptin activates sympathetic metabolically-related neurons in the hypothalamus. To identify leptin receptor-expressing neurons, we created a colony of transgenic reporter mice expressing tdTomato in the presence of the leptin receptor (ObRb) gene. To determine if treatment with leptin activated sympathetic metabolically-related neurons, we performed neuroanatomical tracer studies in the mice. The metabolically-related neurons were identified by microinjection of green FluoSpheres (505/515) into medullary raphe nucleus which is considered the sympathetic metabolic regulatory output center. After microinjection, hypothalamic neurons that express green Fluosphere project to the raphe and therefore are considered metabolic. To identify neuronal activation, we stained for cells expressing c-fos. We found that intracerebroventricular leptin activates hypothalamic neurons, however c-fos positive neurons were not retrogradely labelled raphe-projecting sympathetic metabolic neurons.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:honors-1825 |
| Date | 01 May 2021 |
| Creators | Hixon, Kailee |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Undergraduate Honors Theses |
| Rights | Copyright by the authors., http://creativecommons.org/licenses/by-nc-nd/3.0/ |
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