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- Title
- Neurotransmitter Interactions that Control High-Fat Food Intake.
- Creator
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Gooldy, Timothy, Department of Nutrition, Food, and Exercise Science
- Abstract/Description
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Overconsumption of highly palatable "junk food" contributes to obesity and related metabolic disorders. This project investigated the brain circuitry that allows such eating in excess of the body's energy requirements. We hypothesized that neurotransmitters mediating energy homeostasis and food reward interact within the nucleus accumbens (NAc) to control the intake of palatable foods. Specifically, we examined two neuronal projections from the hindbrain to the NAc: glucagon-like peptide 1 ...
Show moreOverconsumption of highly palatable "junk food" contributes to obesity and related metabolic disorders. This project investigated the brain circuitry that allows such eating in excess of the body's energy requirements. We hypothesized that neurotransmitters mediating energy homeostasis and food reward interact within the nucleus accumbens (NAc) to control the intake of palatable foods. Specifically, we examined two neuronal projections from the hindbrain to the NAc: glucagon-like peptide 1 (GLP-1) and the A2 population of noradrenergic (NA) neurons. Both GLP-1 and A2 cell bodies are located in the nucleus of the solitary tract (NTS) and receive input from the gastrointestinal tract about incoming nutrients during meals. Our lab has previously shown that GLP-1 can act within the NAc to reduce feeding, but that maintenance on high-fat diet (HFD) impairs this response. We hypothesized that this impairment is caused by endogenous opioid activation of mu-opioid receptors (MOR) in NAc. Our studies further examined the HFD-induced impairment in GLP-1 sensitivity and attempted to lay the groundwork for investigating a possible interaction between GLP-1 and MOR in NAc. The next series of studies focused on the role of the A2 projection to NAc. We had previously found that selective lesion of this projection caused overeating and weight gain. Here we asked whether this lesion affects energy expenditure or locomotor activity. We did not observe any significant effects, but also failed to replicate the body weight effect previously obtained, so the data are not conclusive. Further analysis is ongoing.
Show less - Date Issued
- 2012
- Identifier
- FSU_migr_uhm-0144
- Format
- Thesis
- Title
- Interactions Between Vasoactive Intestinal Polypeptide and Dopaminergic Neurons in the Mammalian Olfactory Bulb.
- Creator
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Herman, Allan T., Trombley, Paul Q., Korshunov, Kirill, Department of Biological Science
- Abstract/Description
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In the olfactory bulb (OB), vasoactive intestinal polypeptide (VIP) neurons have a role in modulation of the interneuronal network. It has been known to be expressed in the granule cell layer (GCL), external plexiform layer (EPL), and the glomerular layer (GL). One of the functions of VIP in the OB is maintaining olfactory circadian rhythms (Miller et al., 2014). In the OB, dopaminergic (DA) neurons help process olfactory information through the release of dopamine (DA) onto the presynaptic...
Show moreIn the olfactory bulb (OB), vasoactive intestinal polypeptide (VIP) neurons have a role in modulation of the interneuronal network. It has been known to be expressed in the granule cell layer (GCL), external plexiform layer (EPL), and the glomerular layer (GL). One of the functions of VIP in the OB is maintaining olfactory circadian rhythms (Miller et al., 2014). In the OB, dopaminergic (DA) neurons help process olfactory information through the release of dopamine (DA) onto the presynaptic terminals of olfactory sensory neurons and the dendrites of mitral and tufted (M/T) cells, leading to inhibition of transmitter release (Berkowicz and Trombley, 2000; Davila et al., 2003; Ennis et al., 2001). Tyrosine hydroxylase (TH), the rate-limiting enzyme in the metabolic production of DA, is present in all DA neurons and is used as a histological marker. TH is involved in producing L-DOPA from L-Tyrosine which then enables the production of DA. DA neurons appear to be restricted to a sub-population of neurons within the GL (see Nagayama et al., 2014 for review). The distribution of VIP is less clear and appears to vary among mammalian species. The aim of this project is to determine whether VIP and/or VIP receptors (VPAC2) co-localize with DA in the GL using a combination of immunohistochemistry and fluorescence microscopy. Although the data for VIP remain inconclusive, some cells may show co-labeling of both VPAC2 and TH in the GL suggesting that glomerular DA neurons may be a target of VIP.
Show less - Date Issued
- 2015
- Identifier
- FSU_migr_uhm-0488
- Format
- Thesis
- Title
- Activity-Dependent Regulation of Calcium and Ribosomes in the Chick Cochlear Nucleus.
- Creator
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Call, Cody, Department of Psychology
- Abstract/Description
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Cochlea removal results in the death of 20-30% of neurons in nucleus magnocellularis (NM), a cochlear nucleus of the chick auditory system involved in the precise time-coding of acoustic signals. Within 1 hr of deafferentation, intracellular calcium concentration ([Ca2+]i) rises by up to 400% while the integrity of ribosomes begins to decline—two potentially cytotoxic events. Glutamatergic axons of the auditory nerve have been shown to maintain NM neuron health by activating group I and II...
Show moreCochlea removal results in the death of 20-30% of neurons in nucleus magnocellularis (NM), a cochlear nucleus of the chick auditory system involved in the precise time-coding of acoustic signals. Within 1 hr of deafferentation, intracellular calcium concentration ([Ca2+]i) rises by up to 400% while the integrity of ribosomes begins to decline—two potentially cytotoxic events. Glutamatergic axons of the auditory nerve have been shown to maintain NM neuron health by activating group I and II metabotropic glutamate receptors (mGluRs), maintaining normal [Ca2+]i and ribosomal integrity. This study aimed to determine how [Ca2+]i and ribosomal integrity are maintained by auditory nerve stimulation by selectively blocking group I mGluRs with AIDA and group II mGluRs with LY 341495 during unilateral auditory nerve stimulation. The abundance of Ca2+ in NM neurons was quantified using in vitro fura-2 ratiometric calcium imaging, while ribosomal integrity was assayed in a subset of the same tissue slices using Y10B immunolabeling (Y10B-ir). It was expected that AIDA and LY 341495 would increase [Ca2+]i and these increases would occur in parallel with an elimination in stimulation-induced differences in Y10B-ir between stimulated and unstimulated neurons of a slice. AIDA caused large increases in [Ca2+]i and eliminated differences in Y10B-ir between sides. Surprisingly, LY 341495 failed to cause reliable increases in [Ca2+]i compared to stimulated controls, but still eliminated differences in Y10B-ir between sides. These results suggest dissociation in how calcium and ribosomes are regulated in NM neurons.
Show less - Date Issued
- 2015
- Identifier
- FSU_migr_uhm-0509
- Format
- Thesis
- Title
- The Afferent Circuitry of the Ventromedial Hypothalamus and Its Activation in Paternal Behavior of the Socially Monogamous Prairie Vole.
- Creator
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Rogers, Richard S., Department of Chemistry and Biochemistry
- Abstract/Description
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Paternal behavior is an interesting and important research topic due to its integral contribution to the fitness and well-being of multiple species, including humans. Although paternal behavior is well described in literature, attempts at neurobiological characterization have yielded conflicting results that fail to address brain region interconnectivity. This study was designed to evaluate the relationship between afferent VMH circuitry and the onset of paternal behavior, using the prairie...
Show morePaternal behavior is an interesting and important research topic due to its integral contribution to the fitness and well-being of multiple species, including humans. Although paternal behavior is well described in literature, attempts at neurobiological characterization have yielded conflicting results that fail to address brain region interconnectivity. This study was designed to evaluate the relationship between afferent VMH circuitry and the onset of paternal behavior, using the prairie vole (Microtus ochrogaster) model. Sexually naïve male prairie voles received injections of the retrograde neurotracer Fluoro-Gold (FG), into the VMH. Two weeks later, subjects were exposed to either conspecific pups, contained within a tea-ball, or an empty tea-ball (control) for 1 hr. Immunohistochemical labeling was conducted for both FG and the neuronal activity marker Egr-1, in order to evaluate neuronal and afferent pathway activation between the ventromedial hypothalamus (VMH) and the amygdala (AMYG), bed nucleus of the stria terminalis (BNST), lateral septum (LS) and ventral tegmental area (VTA). Similar to the pathway implicated in the onset of maternal behavior, the results of this study showed pup exposure-induced neuronal activation in the AMYG and BNST, particularly in the efferent pathways from these two brain areas to the VMH. This effect was not found in the LS and VTA projection neurons to the VMH. Together, the data suggests a brain region-specific neuronal activation by pup exposure in particular brain circuitry, implicating its possible involvement in paternal behavior.
Show less - Date Issued
- 2015
- Identifier
- FSU_migr_uhm-0545
- Format
- Thesis
