1996 Fiscal Year Final Research Report Summary
Studies on endogenous itch mediators and their interaction
| Project/Area Number |
08457635
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
応用薬理学・医療系薬学
|
|---|
| Research Institution | TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY |
|---|
Principal Investigator |
KURAISHI Yasushi Toyama Medical and Pharmaceutical University Department of Applied Pharmacology, Professor, 薬学部, 教授 (80111970)
|
|---|
| Project Period (FY) |
1996
|
| Keywords | itch / scratching / substance P / histamine / serotonin / dynorphin / somatostatin / arginine |
|---|
| Research Abstract |
Although it has been claimed that antihistamines can not inhibit itch sensation of many pruritic diseases, histamine, a classical itch mediator released from mast cells, are generally considered to be a major itch mediator in the skin. In this study, to elucidate the mechanisms of itch in the skin, we examined the scratch-inducing potencies of intradermal injections of several endogenous substances that are produced in and released from primary afferent terminals, mast cells, etc. in the skin. Histamine (100 nmol/site) eliciteditch-related behavior (scratching of the injected site) in ICR mice, but not in mice of ddY,BALB/c, C57/BL,WBB6F1 +/+ or CH3/He strain. Serotonin dose-dependently elicited scratching behavior in ICR and ddY mice. Substance P,dynorphin A (1-13) and somatosatatin also produced scratching behavior, while VIP,CGRP,neurokinin A,neurokinin B,PAF and L-arginine were without apparent effects at doses examined. Scratch-inducing effects of substance P and serotonin had several features similar to those of itch in humans, suggesting scratching induced by these substances are due to an itch sensation. Scratch-inducing effect of dynorpjin A(1-13) were roughly additive to that of either substance P or somatostatin. Morphine, an opioid alkaloid known to produce itch in humans, elicited scratching following intracisterna rather than intradermal injection, findings suggesting that opioid and mu-opioid receptors are involved in itch in the central nervous systems rather than in the periphery. Although L-ariginine itself did not elicit scratching, it enhanced scratch-inducing effects of lower doses of substance P,finding suggesting that nitric oxide enhances itch of some pruritic diesase.
|
