Modulation of gut substance P after whole-body irradiation. A new pathological feature.
Exposure to ionizing radiation induces gastrointestinal dysfunction and inflammatory reactions. The present study carried out in the rat, focuses on substance P, an inflammatory mediator implicated in the control of intestinal motility. We have investigated the effects of gamma irradiation on plasma and tissue substance P levels, ileal smooth muscle activity, and properties of specific receptors. Plasma and ileal (mucosa and muscle) substance P concentrations were measured by radioimmunoassay. At doses ranging from 1 to 8 Gy, plasma substance P levels increased in a dose-dependent manner up to four days after irradiation. Ileal mucosal concentration decreased rapidly 1 hr after a 6-Gy irradiation as compared to controls. A second class of binding sites appeared three days after 6 Gy irradiation. In addition, substance P contractile effects measured on isolated ileum showed a fourfold decrease of EC50, three days after 6 Gy irradiation. These results indicated that gamma irradiation induced an increase of plasma levels concomitant with a modification of gastro-intestinal substance P specific binding sites and contractile activity.
Institut de Protection et de Sûreté Nucléaire, Département de Protection de la santé de I'Homme et de Dosimétrie, Section Autonome de Radiobiologie Appliquée à la Médecine, IPSN, Fontenay-aux-Roses, France.
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Esposito
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Linard
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Maubert
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Aigueperse
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Gourmelon
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D007082:Ileum / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D007413:Intestinal Mucosa / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D011829:Radiation Dosage; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000097:blood / Q000378:metabolism* / Q000528:radiation effects; D014916:Whole-Body Irradiation
D013373:Substance P