Acute Choline Deficiency in Germfree, Conventionalized and Open-Animal-Room Rats: Effects of neomycin, chlortetracycline, vitamin B12 and coprophagy prevention

Abstract

Acute choline deficiency was studied in germfree (GF), conventionalized (CONV) and open-animal-room (OAR) rats. With diet A (low cystine, low cholesterol), no rats died; nephropathy and liver fat were less in the GF rats. Liver cholesterol (measured only in OAR rats) increased. Neomycin was without effect in GF and OAR rats. Vitamin B12 lessened the nephropathy and liver fat in only OAR rats; cholesterol was not measured. GF rats fed diet B (high cystine, high cholesterol) showed much less nephropathy and mortality than CONV or OAR rats but increased liver fat. Prevention of coprophagy did not change the response of OAR rats to choline deficiency, nor did neomycin. Vitamin B12 and chlortetracycline decreased the nephropathy and mortality of OAR rats but not liver fat. Vitamin B12 and neomycin had no effect on choline-deficient GF rats. All rats had high liver cholesterol; the GF were the highest. The cholesterol levels were unaffected by choline deficiency, but chlortetracycline and neomycin increased liver cholesterol of choline-deficient rats. We ascribe the lessened nephropathy of GF rats fed choline-deficient diets to their lower metabolic rates, absent bacterial utilization of choline and methionine, greater liver choline synthesis, and lessened decrease in renal acetyl choline. We think the abrupt drop in renal acetyl choline in OAR rats fed such diets leads to nephropathy via renal vasospasm and ischemia.