Modulation by fish oil diet of eicosanoid-induced anion secretion in the rat distal colon

Abstract

Eicosanoids are involved in the mediation of inflammatory and allergic processes in the gut. In order to evaluate a potential beneficial effect of the diet, the effect of mediators of inflammation and of a sensitization against egg albumin on anion secretion across the colon was tested using rats fed on a diet containing 15% fish oil as compared to 15% olive oil as donor animals. Feeding on a fish oil diet significantly reduced the response to bradykinin or phospholipase C, known agonist of prostaglandin-induced secretion, by about 50%. The increase in short-circuit current (Isc) induced by the phospholipase A2 stimulator, melittin, or by distension of the gut wall were only insignificantly inhibited by 15-30%. Administration of egg albumin to the mucosas from animals sensitized against egg albumin induced an indomethacin- and tetrodotoxin-sensitive increase in Isc. This response was, however, only insignificantly (30%) reduced by the fish oil diet. In conclusion, the effect of fish oil diet depends on the stimulus used for activation of prostaglandin release. This suggested that different pools of arachidonic acid are differentially affected by the diet or that certain stimuli for phospholipases are strong enough to overcome the effect of a reduced substrate availability. Consequently, a diet rich in polyunsaturated n-3 fatty acids may only play an adjuvant role for the therapy of inflammatory or allergic intestinal diseases.

Impact of Sensitization and Inflammation on the Interaction of Mast Cells With the Intestinal Epithelium in Rats

“…Stimune ® (specol) is a selected water-in-oil emulsion (for composition see Bokhout et al, 1981), which has less side effects compared to e.g., Freund’s adjuvant (Leenaars et al, 1994). In our hands, also sensitization rates against ovalbumin were increased from 81 to 88% (Hug et al, 1996; Amstutz and Diener, 1997) to 100% (Bell et al, 2015), when replacing Freund’s adjuvant against Stimune ® . The subcutaneous injections were applied on days -15 and -1 before starting with in vitro measurements (Figure 1).…”

“…The subcutaneous injections were applied on days -15 and -1 before starting with in vitro measurements (Figure 1). All animals were successfully sensitized as indicated by the consistent increase of the short-circuit current (I sc ) evoked by antigen exposure in Ussing chamber experiments (see Results), which is not observed in tissues from non-sensitized animals (Hug et al, 1996). For the morphological and molecular biological measurements, in addition samples from untreated, i.e., non-sensitized animals were taken as control group.…”

Effects of multivalent histamine supported on gold nanoparticles: activation of histamine receptors by derivatized histamine at subnanomolar concentrations

“…As the response to histamine evokes chloride secretion in part via stimulation of histamine receptors located on submucosal neurons, the effect of the inhibitory neurotoxin tetrodotoxin, which inhibits the propagation of action potentials via blockade of voltage-dependent Na + channels, on the I sc evoked by the Au-MUDA-HA nanoparticles was investigated. 16,25 Ideed, in the presence of tetrodotoxin (10 −6 mol l −1 at the serosal side), the I sc evoked by Au-MUDA-HA (10 −11 mol l −1 at the serosal side) only amounted to 0.69 ± 0.20 µEq h −1 cm −2 (n = 6) in comparison to 2.92 ± 0.64 µEq h −1 cm −2 in untreated control tissues (P < 0.05, n = 6). The response to native histamine is mediated by stimulation of histamine H 1 and histamine H 2 receptors.…”