Histamine appears to be an important transmitter throughout the Animal Kingdom. Gastropods, in particular, have been used in numerous studies establishing potential roles for this biogenic amine in the nervous system and showing its involvement in the generation of diverse behaviours. And yet, the distribution of histamine has only previously been described in a small number of molluscan species. The present study examined the localization of histamine-like immunoreactivity in the central and peripheral nervous systems of pulmonate snails of the genus Biomphalaria. This investigation demonstrates immunoreactive cells throughout the buccal, cerebral, pedal, left parietal and visceral ganglia, indicative of diverse regulatory functions in Biomphalaria. Immunoreactivity was also present in statocyst hair cells, supporting a role for histamine in graviception. In the periphery, dense innervation by immunoreactive fibers was observed in the anterior foot, perioral zone, and other regions of the body wall. This study thus shows that histamine is an abundant transmitter in these snails and its distribution suggest involvement in numerous neural circuits. In addition to providing novel subjects for comparative studies of histaminegic neurons in gastropods, Biomphalaria is also the major intermediate host for the digenetic trematode parasite, which causes human schistosomiasis. The study therefore provides a foundation for understanding potential roles for histamine in interactions between the snail hosts and their trematode parasites.

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The prospective effects of Lactobacillus sporogenes (probiotics) and/or praziquantel (PZQ) treatment on some parasitological, histological and molecular aspects in Schistosoma mansoni infected mice were studied. The present data recorded that combination between PZQ (300 mg/Kg one dose 7 weeks post infection) and L. sporogenes (12.5 million spore/mice/week for 8 weeks from the first day of infection) reduced worm and ova count. Also, oogram patterns in liver and intestine recorded that treatment with L. sporogenes alone increase number of dead eggs especially in intestine. Histological observations showed significant (P \ 0.05) reduction in the mean values of granuloma diameters in liver and intestine in infected mice groups treated with PZQ and/or L. sporogenes. Single strand breaks (comet assay) showed increase in number of damaged and strong damaged lymphocyte cells in mice infected with S. mansoni and infected treated with PZQ while L. sporogenes administration reduced DNA damage. Flow cytometry also confirmed role of L. sporogenes in reducing significantly DNA damage according to determination of cell cycle analysis apoptosis. It can be concluded that administration of L. sporogenes accompanied with PZQ treatment ameliorates the hepatic and intestinal damage caused by S. mansoni infection.