Serotonin-induced changes in L-leucine transport across rabbit jejunum

Salvador, María Luisa Esteban; Alcalde, Ana Isabel; Marco, R.; Rodríguez-Yoldi, Ma. Jesus

doi:10.1016/0024-3205(96)00450-x

Cited by 9 publications

(3 citation statements)

References 39 publications

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“…On the other hand, serotonin, secreted by enterochromaffin cells in the mucosa and in myenteric plexus neurons, induces a short‐term reduction in the Na + ‐dependent uptake of l ‐leucine in rat intestinal rings. This effect, accompanied by a reduction of the apparent V max , as found in the present study, is triggered by intracellular processes related to protein kinase C [26]. Furthermore, preliminary experiments performed in our laboratory demonstrate that cholecystokinin also inhibits galactose uptake in rat intestinal rings [27].…”

Section: Discussionsupporting

confidence: 72%

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Presence of leptin receptors in rat small intestine and leptin effect on sugar absorption

et al. 1998

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Leptin is involved in food intake and thermogenesis regulation. Since leptin receptor expression has been found in several tissues including small intestine, a possible role of leptin in sugar absorption by the intestine was investigated. Leptin inhibited D-galactose uptake by rat small intestinal rings 33% after 5 min of incubation. The inhibition increased to 56% after 30 min. However, neither at 5 min nor at 30 min did leptin prevent intracellular galactose accumulation. This leptin effect was accompanied by a decrease of the active sugar transport apparent V mx (20 vs. 4.8 W Wmol/g wet weight 5 min) and apparent K m (15.8 vs. 5.3 mM) without any change in the phlorizinresistant component. On the other hand, immunohistochemical experiments using anti-leptin monoclonal antibodies recognized leptin receptors in the plasma membrane of immune cells located in the lamina propria. These results indicate for the first time that leptin has a rapid inhibitory effect on sugar absorption and demonstrate the presence of leptin receptors in the intestinal mucosa.z 1998 Federation of European Biochemical Societies.

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Section: Discussionsupporting

confidence: 72%

“…They regulate chloride secretion by enterocytes through an indirect mechanism, which is apparently mediated by histamine [23]. As the effects of several hormones and peptides on nutrient uptake by brush border transporters are mediated by protein kinases [25, 26], it can be suggested that cytokines could act in the same way.…”

Section: Discussionmentioning

confidence: 99%

Presence of leptin receptors in rat small intestine and leptin effect on sugar absorption

et al. 1998

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“…Parallel to morphological studies, numerous pharmacological experiments provided evidence that 5‐HT has extremely diverse roles in the gastrointestinal tract. This monoamine influences the transport of nutrients, and inhibits the Na + ‐dependent system of transport of D‐galactose and L‐leucin in rabbit ileum in vitro (Salvador et al, 1996, 1997). Furthermore, 5‐HT alters the intestinal electrolyte transport; increases fluid, Cl − , Na + , and K + secretion into the intestinal lumen (Donowitz et al, 1980; Kellum et al, 1994; Borman and Burleigh, 1997; McLean and Coupar, 1998); inhibits Cl − /HCO

_{−}^{3}

exchange in villus cells; and stimulates Na + /H + exchange in crypts (Sundaram et al, 1991).…”

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confidence: 99%

Serotonin in the rabbit ileum: Localization, uptake, and effect on motility

et al. 2003

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Repeated experiments to localise serotonin in the myenteric plexus of rabbit ileum failed. After preincubation in serotonin (10 -5 M), an extensive varicose fibre system was detected by immunocytochemical methods. Stained fibres left the myenteric plexus and ran to the muscle layers. Labelled cell bodies could not be found, even after pretreatment with colchicine or pargyline. Application of reserpine (10 -5 M) and fluoxetine (10 -5 M) prevented serotonin uptake. Antisera against tryptophan hydroxylase revealed a rich fibre system, including those processes that entered the tertiary plexus. These fibres were able to accumulate serotonin, but again the cell bodies could not be detected. Serotonin caused concentrationdependent contraction in the longitudinal muscle layer of the rabbit ileum. Pretreatment with tetrodotoxin strongly reduced the effect of serotonin. Preapplication of atropine caused a slight decrease of response evoked by serotonin. Combined administration of tetrodotoxin and atropine significantly reduced the responses to serotonin, but did not abolish them. At the same time, agonists of 5-HT 2 and 5-HT 4 receptors caused concentration-dependent contractions. Our studies show that: 1) Without pretreatment, serotonin cannot be detected in the myenteric plexus of rabbit ileum. 2) An extensive uptake system works in this plexus. If released from myenteric nerve fibres, serotonin may evoke contractions in indirect and direct ways. 3) There may be an extrinsic serotoninergic innervation from the mesenteric ganglia. 4) Serotonin exerts its effect through 5-HT 2 and 5-HT 4 receptors on smooth muscle cells and nerve elements. Anat Rec Part A 271A: 368 -376, 2003.

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Recent advances on the importance of the serotonin transporter SERT in the rat intestine

Martel

2006

Pharmacological Research

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Serotonin-induced changes in L-leucine transport across rabbit jejunum

Cited by 9 publications

References 39 publications

Presence of leptin receptors in rat small intestine and leptin effect on sugar absorption

Presence of leptin receptors in rat small intestine and leptin effect on sugar absorption

Serotonin in the rabbit ileum: Localization, uptake, and effect on motility

Recent advances on the importance of the serotonin transporter SERT in the rat intestine

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