Evidence for the absence of an intestinal adaptive mechanism to compensate for C. parvum-induced amino acid malabsorption in suckling rats.
In order to assess the impact of Cryptosporidium parvum on host intestinal physiology, we investigated absorption of the two principal amino acids in dam's milk (leucine, glutamate), using Ussing chambers and RT-PCR analyses. Experiments were performed in both heavily (ileum) and mildly (duodenum) infected segments of the small intestine at the peak of infection [day 8 post-infection (PI)] and after spontaneous clearance of the parasite (day 17 PI). At day 8 PI, amino acid fluxes across the mucosa were decreased throughout the small intestine (P<0.01) and EAAT3 mRNA expression was reduced ( from -49% to -28%). At day 17 PI, leucine and glutamate fluxes were normalized but the decrease in EAAT3 mRNA levels persisted (from -31% to -46%). Our results demonstrate that cryptosporidiosis induces major amino acid malabsorption involving the entire small intestine which is not counterbalanced by any up-regulation, even after spontaneous clearance of the parasite.
Topouchian
A
A
Laboratoire de Biologie Animale et Parasitaire, Faculté des Sciences Pharmaceutiques et Biologiques, Université René Descartes, 75006 Paris, France.
Huneau
J F
JF
Barbot
L
L
Rome
S
S
Gobert
J G
JG
Tomé
D
D
Kapel
N
N
D027322:Amino Acid Transport System X-AG / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000833:Animals, Suckling; D003457:Cryptosporidiosis / Q000378:metabolism / Q000469:parasitology / Q000503:physiopathology*; D016785:Cryptosporidium parvum / Q000472:pathogenicity* / Q000502:physiology; D004195:Disease Models, Animal; D004386:Duodenum / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D050580:Excitatory Amino Acid Transporter 3; D005260:Female; D050491:Glutamate Plasma Membrane Transport Proteins; D018698:Glutamic Acid / Q000378:metabolism; D007082:Ileum / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D007413:Intestinal Mucosa / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D007930:Leucine / Q000378:metabolism; D008286:Malabsorption Syndromes; D051381:Rats; D017207:Rats, Sprague-Dawley; D013047:Specific Pathogen-Free Organisms; D027981:Symporters / Q000235:genetics / Q000378:metabolism
D027322:Amino Acid Transport System X-AG; D050580:Excitatory Amino Acid Transporter 3; D050491:Glutamate Plasma Membrane Transport Proteins; C493398:Slc1a1 protein, rat; D027981:Symporters; D018698:Glutamic Acid; D007930:Leucine