The aging U.S. population has led to substantial increases in resources allocated to the prevention and treatment of age-related neurodegenerative conditions, including disorders of cognitive decline. Alterations in homeostatic functions such as energy balance and sleep patterns are also frequently seen in the elderly and these changes often precede and predict subsequent cognitive decline. A novel hypothesis is that some of these seemingly disparate manifestations of age-related deficits may share underlying neurobiological mechanisms; that is, brain regions that are involved in homeostasis regulate the activity of neurotransmitter systems and brain regions that mediate the appropriate behavioral and cognitive responses to physiological challenges, and these interactions may be impacted in aging. We have shown that aging is associated with loss of hypothalamic hypocretin/orexin neurons-a cell population that regulates energy balance and sleep/wake stability. Because hypocretin/orexin neurons also regulate neurotransmission in brain regions that underlie several aspects of attention, learning and memory we hypothesize that these neuropeptides link physiological function with age-related cognitive decline. The testable corollary to this hypothesis is that upregulation of the orexin/hypocretin system in aging will allow for preservation or restoration of these functions.
In Aim 1 we will combine DREADD (designer receptors exclusively activated by designer drugs) and in vivo neurochemical approaches to determine the effect of acute orexin/hypocretin activation or inhibition on behavior and neurotransmission in several relevant brain regions.
In Aim 2 we will use virus-mediated gene transfer and to perform chronic manipulations of the orexin/hypocretin system in a longitudinal animal model of aging. We will examine how these manipulations alter food and water intake, body composition and markers of neurotransmitter systems and neuronal activation.
In Aim 3 we will test the hypothesis that the hypocretin/orexin system supports attentional performance across the life span using both acute and chronic manipulations of hypocretin/orexin transmission. Collectively, these studies will implicate the orexin/hypocretin system as a major contributing factor in cognitive and homeostatic manifestations of age-related neural dysfunction, and suggest a potential new target for development of therapies that prevent, delay or ameliorate age-related cognitive decline.

Public Health Relevance

Aging is associated with changes in physiological function that often precede and predict later cognitive decline. Here we will examine the role of hypothalamic systems-focusing especially on the orexin/hypocretin neuropeptide neurons-that serve as 'physiological integrators' in age-related decline in neurochemical, behavioral and cognitive functions. These studies may point to novel therapeutic targets for slowing or preventing age-related cognitive decline.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG050518-03
Application #
9291400
Study Section
Biobehavioral Regulation, Learning and Ethology Study Section (BRLE)
Program Officer
Wagster, Molly V
Project Start
2015-08-15
Project End
2020-05-31
Budget Start
2017-07-01
Budget End
2018-05-31
Support Year
3
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of South Carolina at Columbia
Department
Pharmacology
Type
Schools of Medicine
DUNS #
041387846
City
Columbia
State
SC
Country
United States
Zip Code
29208
Burk, Joshua A; Blumenthal, Sarah A; Maness, Eden B (2018) Neuropharmacology of attention. Eur J Pharmacol 835:162-168
Calva, Coleman B; Fayyaz, Habiba; Fadel, Jim R (2018) Increased acetylcholine and glutamate efflux in the prefrontal cortex following intranasal orexin-A (hypocretin-1). J Neurochem 145:232-244
Calva, Coleman B; Fadel, Jim R (2018) Intranasal administration of orexin peptides: Mechanisms and therapeutic potential for age-related cognitive dysfunction. Brain Res :
Wilson, Marlene A; Fadel, Jim R (2017) Cholinergic regulation of fear learning and extinction. J Neurosci Res 95:836-852
Sharko, Amanda C; Fadel, Jim R; Kaigler, Kris F et al. (2017) Activation of orexin/hypocretin neurons is associated with individual differences in cued fear extinction. Physiol Behav 178:93-102
Hagar, Janel M; Macht, Victoria A; Wilson, Steven P et al. (2017) Upregulation of orexin/hypocretin expression in aged rats: Effects on feeding latency and neurotransmission in the insular cortex. Neuroscience 350:124-132
Hunt, Pamela S; Burk, Joshua A; Barnet, Robert C (2016) Adolescent transitions in reflexive and non-reflexive behavior: Review of fear conditioning and impulse control in rodent models. Neurosci Biobehav Rev 70:33-45
Fadel, Jim R; Reagan, Lawrence P (2016) Stop signs in hippocampal insulin signaling: the role of insulin resistance in structural, functional and behavioral deficits. Curr Opin Behav Sci 9:47-54
Zajo, Kristin N; Fadel, Jim R; Burk, Joshua A (2016) Orexin A-induced enhancement of attentional processing in rats: role of basal forebrain neurons. Psychopharmacology (Berl) 233:639-47