Three Types of A11 Neurons Project to the Rat Spinal Cord

Ozawa, Hidechika; Yamaguchi, Tsuyoshi; Hamaguchi, Shinsuke; Yamaguchi, Shigeki; Ueda, Seinosuke

doi:10.1007/s11064-017-2219-7

Cited by 13 publications

(10 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Among these regions, we focused on the locus coeruleus (LC; the A6 region), because activation of the nucleus suppresses visceromotor reflex response to colorectal distension (35). Additionally, roles of the A11 region, the principle source of dopamine in the spinal cord (4,8,25), were examined. Our results revealed that the brainstem monoaminergic nuclei activate the spinal defecation center, resulting in enhancement of colorectal motility.…”

Section: Introductionmentioning

confidence: 99%

Roles of the noradrenergic nucleus locus coeruleus and dopaminergic nucleus A11 region as supraspinal defecation centers in rats

Nakamori

Naitou

Horii

et al. 2019

American Journal of Physiology-Gastrointestinal and Liver Physi

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

Roles of the noradrenergic nucleus locus coeruleus and dopaminergic nucleus A11 region as supraspinal defecation centers in rats

Nakamori

Naitou

Horii

et al. 2019

American Journal of Physiology-Gastrointestinal and Liver Physi

View full text Add to dashboard Cite

show abstract

“…This is in contrast to responses in male rats, in which both serotonergic and dopaminergic pathways are activated (Naitou et al 2018). It is well known that dopamine in the lumbar spinal cord is mainly released by descending neurons projecting from the A11 region of the diencephalon (Skagerberg et al 1982;Koblinger et al 2014;Ozawa et al 2017). Taking into account that the density of descending dopaminergic fibres is lower in females than in males (Pappas et al 2010), the lack of involvement of dopaminergic pathways in female rats would be due to insufficient release of dopamine from the descending fibres.…”

Section: Discussionmentioning

confidence: 83%

“…2014; Ozawa et al . 2017). Taking into account that the density of descending dopaminergic fibres is lower in females than in males (Pappas et al .…”

Section: Discussionmentioning

confidence: 99%

Sexually dimorphic response of colorectal motility to noxious stimuli in the colorectum in rats

Hara

Ehara

Shiina

et al. 2020

The Journal of Physiology

View full text Add to dashboard Cite

Key points This study showed a remarkable sex difference in responses of colorectal motility to noxious stimuli in the colorectum in rats: colorectal motility was enhanced in response to intracolonic administration of a noxious stimulant, capsaicin, in male rats but not in female rats. The difference in descending neurons from the brain to spinal cord operating after noxious stimulation could be responsible for the sex difference. In male rats, serotoninergic and dopaminergic neurons are dominantly activated, both of which activate the spinal defaecation centre. In female rats, GABAergic neurons in addition to serotoninergic neurons are activated. GABA may compete for facilitative action of 5‐HT in the spinal defaecation centre, and thereby colorectal motility is not enhanced in response to intracolonic administration of capsaicin. The findings provide a novel insight into pathophysiological mechanisms of sex differences in functional defaecation disorders such as irritable bowel syndrome. Abstract We previously demonstrated that noxious stimuli in the colorectum enhance colorectal motility through activation of descending pain inhibitory pathways in male rats. It can be expected that the regulatory mechanisms of colorectal motility differ in males and females owing to remarkable sex differences in descending pain inhibitory pathways. Thus, we aimed to clarify sex differences in responses of colorectal motility to noxious stimuli in rats. Colorectal motility was measured in vivo in anaesthetized rats. Administration of a noxious stimulant, capsaicin, into the colorectal lumen enhanced colorectal motility in male rats but not in female rats. Quantitative PCR and immunohistochemistry showed that TRPV1 expression levels in the dorsal root ganglia and in the colorectal mucosa were comparable in male and female rats. When a GABAA receptor inhibitor was intrathecally administered to the L6–S1 level of the spinal cord, colorectal motility was facilitated in response to intracolonic capsaicin even in female rats. The capsaicin‐induced response in the presence of the GABA blocker in female rats was inhibited by intrathecal administration of 5‐HT2 and ‐3 receptor antagonists but not by a D2‐like dopamine receptor antagonist. Our findings demonstrate that intracolonic noxious stimulation activates GABAergic and serotoninergic descending neurons in female rats, whereas serotoninergic and dopaminergic neurons are dominantly activated in male rats. Thus, the difference in the descending neurons operating after noxious stimulation would be responsible for the sexually dimorphic responses of colorectal motility. Our findings provide a novel insight into pathophysiological mechanisms of sex differences in functional defaecation disorders such as irritable bowel syndrome.

show abstract

“…Both D1-like and D2-like receptors exist in the rat spinal cord at a high density [184]. There are descending dopaminergic pathways to the spinal dorsal horn from the periventricular posterior region (A11) of the hypothalamus in rats [185,186,187,188]. Intrathecally-administrated apomorphine (a D2 receptor agonist) inhibited thermally and chemically evoked noxious responses in rats ([189]; see [190] for review).…”

Section: Effects Of Other Endogenous Pain Modulators On Synaptic Tmentioning

confidence: 99%

Cellular Mechanisms for Antinociception Produced by Oxytocin and Orexins in the Rat Spinal Lamina II—Comparison with Those of Other Endogenous Pain Modulators

Kumamoto

2019

Pharmaceuticals

View full text Add to dashboard Cite

Much evidence indicates that hypothalamus-derived neuropeptides, oxytocin, orexins A and B, inhibit nociceptive transmission in the rat spinal dorsal horn. In order to unveil cellular mechanisms for this antinociception, the effects of the neuropeptides on synaptic transmission were examined in spinal lamina II neurons that play a crucial role in antinociception produced by various analgesics by using the whole-cell patch-clamp technique and adult rat spinal cord slices. Oxytocin had no effect on glutamatergic excitatory transmission while producing a membrane depolarization, γ-aminobutyric acid (GABA)-ergic and glycinergic spontaneous inhibitory transmission enhancement. On the other hand, orexins A and B produced a membrane depolarization and/or a presynaptic spontaneous excitatory transmission enhancement. Like oxytocin, orexin A enhanced both GABAergic and glycinergic transmission, whereas orexin B facilitated glycinergic but not GABAergic transmission. These inhibitory transmission enhancements were due to action potential production. Oxytocin, orexins A and B activities were mediated by oxytocin, orexin-1 and orexin-2 receptors, respectively. This review article will mention cellular mechanisms for antinociception produced by oxytocin, orexins A and B, and discuss similarity and difference in antinociceptive mechanisms among the hypothalamic neuropeptides and other endogenous pain modulators (opioids, nociceptin, adenosine, adenosine 5’-triphosphate (ATP), noradrenaline, serotonin, dopamine, somatostatin, cannabinoids, galanin, substance P, bradykinin, neuropeptide Y and acetylcholine) exhibiting a change in membrane potential, excitatory or inhibitory transmission in the spinal lamina II neurons.

show abstract

Three Types of A11 Neurons Project to the Rat Spinal Cord

Cited by 13 publications

References 35 publications

Roles of the noradrenergic nucleus locus coeruleus and dopaminergic nucleus A11 region as supraspinal defecation centers in rats

Roles of the noradrenergic nucleus locus coeruleus and dopaminergic nucleus A11 region as supraspinal defecation centers in rats

Sexually dimorphic response of colorectal motility to noxious stimuli in the colorectum in rats

Cellular Mechanisms for Antinociception Produced by Oxytocin and Orexins in the Rat Spinal Lamina II—Comparison with Those of Other Endogenous Pain Modulators

Contact Info

Product

Resources

About