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Changes in orexin (hypocretin) neuronal expression with normal aging in the human hypothalamus
Nicholas J Hunt1, Michael L Rodriguez2, Karen A Waters3
1Department of Medicine, Central Clinical School, University of Sydney, New South Wales, Australia; SIDS and Sleep Apnea Laboratory, BOSCH Institute of Biomedical Research, University of Sydney, New South Wales, Australia.
Neurobiology of Aging
|September 13, 2014
Summary
Orexin (Ox) expression decreases with human aging and development. This reduction in the tuberal hypothalamus may impact sleep regulation throughout life.
Area of Science:
- Neuroscience
- Aging Research
- Sleep Science
Background:
- Animal studies suggest orexin (Ox) expression changes impact sleep regulation during aging.
- Orexin, a neuropeptide, plays a crucial role in maintaining wakefulness and regulating sleep-wake cycles.
Purpose of the Study:
- To investigate changes in orexin A and B expression in the human tuberal hypothalamus across different age groups.
- To determine if orexin expression declines with normal human maturation and aging.
Main Methods:
- Examined orexin-immunoreactive (Ox-ir) neurons in the tuberal hypothalamus of infants, children, young adults, and older adults.
- Quantified neuronal expression by percentage of Ox-ir neurons, neuron density (Ox-ir neurons/mm²), and regional distribution within the hypothalamus.
Main Results:
- A significant decrease in the percentage of Ox-ir neurons was observed between infants and older adults (23%) and between younger and older adults (10%).
- These age-related decreases in orexin expression were localized to the dorsal medial and/or perifornical hypothalamus.
- Adults showed a 9%-24% reduction in Ox-ir neurons/mm² compared to infants and/or children.
Conclusions:
- Orexin expression significantly decreases with normal human maturation and aging.
- Reduced orexin levels may contribute to age-associated alterations in sleep regulation.
- These findings highlight the role of orexin in developmental and aging-related changes in sleep patterns.
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