Serotonin-induced changes in L-leucine transport across rabbit jejunum.
The aim of the present study has been to determine the effect of serotonin (5-HT) on the absorption of L-leucine across the rabbit jejunum. The results show that serotonin significantly diminishes the uptake and steady-state tissue accumulation and the mucosal to serosal flux of L-leucine. This effect does not change with previous intestinal exposure of the mucosa to the 5-HT. Serotonin does not seem to modify amino acid simple diffusion across the intestinal epithelium. The effect on the amino acid uptake is due to an inhibition of the Na(+)-dependent system of transport, mainly through a reduction of the apparent Vmax. Moreover, this hormone, added to the incubation solution, does not affect the L-leucine uptake across brush border membrane vesicles. In presence of trifluoroperazine, TMB-8 and staurosporine, the serotonin effect disappears. These results suggest an effect mediated by intracellular processes related to protein kinase C which inhibit the intestinal absorption of L-leucine.
Salvador
M T
MT
Departamento de Fisiología, Facultad de Veterinaria, Zaragoza, Spain.
Rodriguez-Yoldi
M C
MC
Alcalde
A I
AI
Marco
R
R
Rodríguez-Yoldi
M J
MJ
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004058:Diffusion; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007408:Intestinal Absorption / Q000187:drug effects*; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism*; D008297:Male; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014268:Trifluoperazine; D012701:Serotonin; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D012964:Sodium; D011493:Protein Kinase C; D007930:Leucine; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate