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Published on: July 26, 2022
Lesions of the ventral ascending noradrenergic bundles decrease the stress response to occlusal disharmony in rats
Toshihiro Yoshihara1, Yasutaka Yawaka
1Division of Pediatric Dentistry, Department of Oral Functional Science, Hokkaido University Graduate School of Dental Medicine, North 13, West 7, Kita-ku, Sapporo 060-8586, Japan. tyoshi03@den.hokudai.ac.jp
Neuroscience Letters
|August 26, 2011
Summary
Occlusal disharmony triggers chronic stress, activating the hypothalamic-pituitary-adrenal (HPA) axis. Noradrenergic pathways from the brainstem to the hypothalamus are crucial for this stress response.
Area of Science:
- Neuroscience
- Stress Physiology
- Endocrinology
Background:
- Occlusal disharmony is a form of chronic stress.
- This stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN).
- The hypothalamic-pituitary-adrenal (HPA) axis is stimulated, leading to stress hormone release.
Purpose of the Study:
- To investigate the role of ventral ascending noradrenergic bundles (V-NAB) in the HPA axis response to occlusal disharmony.
- To examine the relationship between noradrenaline (NA) levels in the PVN and plasma corticosterone.
Main Methods:
- Rats were subjected to occlusal disharmony via acrylic caps on lower incisors.
- 6-hydroxydopamine (6-OHDA), a neurotoxin, was microinjected into the V-NAB to lesion noradrenergic pathways.
- Extracellular NA in the PVN and plasma corticosterone levels were measured.
Main Results:
- Microinjection of 6-OHDA into the V-NAB significantly reduced extracellular NA levels in the PVN.
- The magnitude of plasma corticosterone response to occlusal disharmony was diminished following V-NAB lesioning.
- These findings indicate a reduction in both central noradrenergic activity and HPA axis output.
Conclusions:
- Ventral ascending noradrenergic bundles (V-NAB) play a significant role in the HPA axis activation induced by occlusal disharmony.
- Noradrenergic projections from the brainstem to the PVN are critical mediators of the stress response to dental issues.
