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Nakamori H, Naitou K, Horii Y, Shimaoka H, Horii K, Sakai H, Yamada A, Furue H, Shiina T, Shimizu Y. Roles of the noradrenergic nucleus locus coeruleus and dopaminergic nucleus A11 region as supraspinal defecation centers in rats. Am J Physiol Gastrointest Liver Physiol 2019; 317:G545-G555. [PMID: 31460791 DOI: 10.1152/ajpgi.00062.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We previously demonstrated that administration of norepinephrine, dopamine, and serotonin into the lumbosacral defecation center caused propulsive contractions of the colorectum. It is known that the monoamines in the spinal cord are released mainly from descending neurons in the brainstem. In fact, stimulation of the medullary raphe nuclei, the origin of descending serotonergic neurons, enhances colorectal motility via the lumbosacral defecation center. Therefore, the purpose of this study was to examine the roles of the noradrenergic nucleus locus coeruleus (LC) and dopaminergic nucleus A11 region in the defecation reflex. Colorectal motility was measured with a balloon in anesthetized rats. Electrical stimulation of the LC and A11 region increased colorectal pressure only when a GABAA receptor antagonist was injected into the lumbosacral spinal cord. The effects of the LC stimulation and A11 region stimulation on colorectal motility were inhibited by antagonists of α1-adrenoceptors and D2-like dopamine receptors injected into the lumbosacral spinal cord, respectively. Spinal injection of a norepinephrine-dopamine reuptake inhibitor augmented the colokinetic effect of LC stimulation. The effect of stimulation of each nucleus was abolished by surgical severing of the parasympathetic pelvic nerves. Our findings demonstrate that activation of descending noradrenergic neurons from the LC and descending dopaminergic neurons from the A11 region causes enhancement of colorectal motility via the lumbosacral defecation center. The present study provides a novel concept that the brainstem monoaminergic nuclei play a role as supraspinal defecation centers.NEW & NOTEWORTHY The present study demonstrates that electrical and chemical stimulations of the locus coeruleus or A11 region augment contractions of the colorectum. The effects of locus coeruleus and A11 stimulations on colorectal motility are due to activation of α1-adrenoceptors and D2-like dopamine receptors in the lumbosacral defecation center, respectively. The present study provides a novel concept that the brainstem monoaminergic nuclei play a role as supraspinal defecation centers.
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Affiliation(s)
- Hiroyuki Nakamori
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Kiyotada Naitou
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Yuuki Horii
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Hiroki Shimaoka
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Kazuhiro Horii
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Hiroki Sakai
- Department of Pathogenetic Veterinary Science, Laboratory of Pathology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.,Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan
| | - Akihiro Yamada
- Department of Neurophysiology, Hyogo College of Medicine, Nishinomiya, Japan
| | - Hidemasa Furue
- Department of Neurophysiology, Hyogo College of Medicine, Nishinomiya, Japan
| | - Takahiko Shiina
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Yasutake Shimizu
- Department of Basic Veterinary Science, Laboratory of Physiology, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.,Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan
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