| Co-Investigator(Kenkyū-buntansha) |
YOKOTA Makoto Kyushu Dental College, Dental School, Professor, 歯学部, 教授 (40107298)
INENAGA Kiyotoshi Kyushu Dental College, Dental School, Professor, 歯学部, 教授 (90131903)
ONO Kentaro Kyushu Dental College, Dental School, Assistant Prof., 歯学部, 助手 (40316154)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
Although pilocarpine, a muscarinic receptor agonist, is used as a sialogogue, it is well-known in animal experiments that it also induces water intake. However, mechanisms underlying the relationships between these events are unknown. To address this problem, we examined water intake and parotid salivary secretion in conscious rats. Intraperitonially injected pilocarpine increased both water intake and salivary secretion. Intracerebroventricularly injected pilocarpine also induced water intake but not salivary secretion. Intracerebroventricularly applied atropine, a muscarinic receptor antagonist, suppressed the increased water intake by the intraperitonially and intracerebroventricularly applied pilocarpine. However it did not affect salivary secretion by peripheral pilocarpine. We conclude that peripherally injected pilocarpine affects the parotid glands and the thirst center in the central nervous system. Salivary secretion and water intake may be respectively due to mainly the peri
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pheral and central responses of pilocarpine.
In the next study, we made experimentation of effects of another sialogogue cevimeline on salivation from the parotid gland and water intake in conscious rats. The intraperitoneal injection of cevimeline over 40 μmol/kg induced salivation, but not water intake. On the other hand, the intracerebroventricular injection of cevimeline over 300 nmol induced water intake without inducing salivation. Compared with our previous study, the concentration of cevimeline was needed several ten times of pilocarpine, to induce salivation following the intraperitoneal injection, but it was needed thousands times to induce water intake following the intracerebroventricular injection. These indicate that intraperitoneally injected-cevimeline induces salivation without inducing water intake, suggesting lesser affection on thirst center in the brain than pilocarpine.
Additionally, we have found c-fos expression in brain regions, especially, circumventricular organs and hypothalamic nuclei, by i.c.v injection of pilolarpine. Less
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