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Pathological and immunohistochemical investigations were carried out on the middle intestine of uninfected and parasitized brown trout, Salmo trutta L., from the Ceresone Channel in North Italy. Eighty-six brown trout were sampled by electrofishing, and 32 (37.2%) were infected with Cyathocephalus truncatus Pallas, 1781 (Cestoda). The intensity of infection ranged from 1 to 82 parasites per host and the most infected segments were the anterior (near the pyloric caeca region) and the central part of the middle intestine. Immunohistochemical tests were applied on sections of intestinal tissue of healthy and infected fish, and the presence of substance P (SP), calcitonin gene related peptide (CGRP), met-enkephalin, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY) and serotonin (5-HT) was documented. Endocrine epithelial cells of the tunica mucosa were positive to SP-, CGRP-, met-enkephalin-, and NPY-like peptides and 5-HT antisera; moreover, a higher number of these cells were recorded in the intestine of infected trout in comparison to uninfected fish. In addition, in parasitized S. trutta, SP-like and 5-HT immunoreactivities were found in likely immuno-related cells of the tunica propria-submucosa. Nerve cell bodies and terminals in the myenteric plexus were immunoreactive to almost all the tested peptides and 5-HT antisera. These data provide evidence for the role of the neuroendocrine system of S. trutta in the modulation of inflammatory responses to C. truncatus. Results are discussed with respect to a peptidergic involvement and host immune response to an intestinal tapeworm.

Aim: In vitro and in vivo challenge studies were undertaken to develop an in-feed additive of microencapsulated propionic, sorbic acids and pure botanicals to control Campylobacter jejuni in broilers at slaughter age. Methods and Results: Organic acids (OA) and pure botanicals were tested in vitro against Camp. jejuni, whereas in vivo, chickens were fed either a control diet, or increasing doses of the additive for 42 days (experiment 1); in the second experiment, chickens received the additive at 0Á1 or 0Á3% from day 0 to 21 or from day 22 to 42. The additive consistently reduced Camp. jejuni caecal counts at any given dose (exp. 1) or inclusion plan (exp. 2). Moreover, it was able to reduce the number of goblet cells and modify mucin glycoconjugates biosynthesis pattern. Conclusions: We developed an additive that was effective in reducing Camp. jejuni in slaughter-age chickens even at low doses (0Á1%). That efficacy was the result of the synergistic action between OA and botanicals. Significance and Impact of the Study: This study provides a strategy to reduce Camp. jejuni in broilers and, as a consequence, to improve the safety of the food chain. Moreover, data suggest that a treatment limited to the last weeks before slaughter would allow to save on inclusion of the additive throughout the whole production cycle.

Immunohistochemical and pathological studies were carried out on the digestive tract of parasitized and uninfected specimens of Salmo trutta (L.). A total of 124 brown trout were collected on several occasions from 3 tributaries of the Brenta River, northern Italy. Twenty-eight individuals of S. trutta (22.6%) were parasitized with Pomphorhynchus laevis (Müller, 1776). The occurrence of P. laevis in the trout gut significantly increased the number of endocrine cells immunoreactive to calcitonin gene-related peptide (CGRP), β-endorphin, met-enkephalin, neuropeptide Y (NPY) and Substance P (SP) antisera. Moreover, bombesin-, cholecistokinin-8-(CCK-8), leu-enkephalin-and serotonin-(5-HT)-like immunoreactive cells were less numerous in the intestine of the parasitized brown trout. A strong positive immunoreactivity was observed in nerve fibres and neurones of the myenteric plexus of the parasitized fish; the antisera involved in this positive reactivity were bombesin, metenkephalin, SP and vasoactive intestinal peptide (VIP). More neurones immunoreactive to anti-CGRP and anti-5-HT sera were noted in the myenteric plexus and in the inner layer of the tunica muscularis of the infected fish. Most of the above-mentioned neuromodulators are known to control gut motility, digestive/absorptive processes, as well as the immune response. The changes induced by parasites in the neuroendocrine system of the brown trout are discussed. KEY WORDS: Acanthocephalan infection · Immunohistochemical · Neuromodulators · Digestive tract · Salmo trutta Resale or republication not permitted without written consent of the publisherDis Aquat Org 51: [27][28][29][30][31][32][33][34][35] 2002 Pomphorhynchus laevis is a common parasite of several species of freshwater fishes (Bykhovskaya-Pavlovskaya 1964); indeed, in the study area, among the acanthocephalan parasites of Salmo trutta, P. laevis was the most frequent (Dezfuli et al. 2001). Histopathological effects of this worm on fishes, such as Leuciscus cephalus were reported by Mehlhorn et al. (1988) and Dezfuli (1991).Host structural modifications due to enteric helminths are the counterpart of biochemical and physiological changes (Castro 1992, Fairweather 1997. In mammals, the nervous, endocrine, and immune systems cooperate to elicit host responses to the intestinal parasites (Fairweather 1997), and many peptides and amines are involved in the communication among cells of these systems (Blalock 1989, O'Dorisio & Panerai 1990. With reference to mammals, the topic that enteric helminths can affect the distribution of neuromodulators of the host gut and induce host responses has drawn the attention of a number of workers in the recent past (McKay et al. 1991, Varilek et al. 1991, Foster & Lee 1996, Fairweather 1997. However, to date, there have been only very limited observations on the occurrence and distribution of neuromodulators in the intestine of infected fishes (Maule et al. 1989, Dezfuli et al. 2000. Recently, with immunohistochemical methods, the presence and freque...