ANEURINE (THIAMINE) 



rat intestine. The question as to whether acetyl aneurine is an 

 additional nerve messenger has not yet been answered, but the idea 

 is an interesting one, because if it is essential for the proper functioning 

 of the nervous system, its absence may result in atrophy of the nerves, 

 a characteristic feature of vitamin B^ deficiency that is not explicable 

 if aneurine acts simply as a metabolic catalyst of pyruvic acid oxida- 

 tion or decarboxylation. Fiuther work on the connection between 

 aneurine and the nervous system is highly desirable. 



An attempt to explain the connection between aneurine deficiency 

 and the appearance of nerve lesions was made by D. Glick and W. 

 Antopol.i^ They noted that many of the symptoms of vitamin B^ 

 deficiency, such as hypochlorhydria, loss of muscular tone, certain 

 forms of nerve dysfunction and tachycardia, were relieved by adminis- 

 tration of choline esters, and that certain symptoms of hyperthyroidism 

 were alleviated by aneurine and choline esters. They suggested, 

 therefore, that aneurine might inhibit choline esterase activity so that 

 a deficiency of the vitamin might result in enhanced enzyme activity 

 and a reduced concentration of acetyl choline. 



This suggestion, if true, might also explain McHenry's observation 

 that, aneurine cured fatty livers in rats kept on a low choline diet, for 

 the increased choline esterase activity produced by administration of 

 the vitamin might lead to an increased availability of free choline, 

 which would tend to reduce the amount of fat in the liver. When this 

 ingenious hypothesis was tested, it was found that aneurine did 

 inhibit choline esterase, but only in concentrations far in excess of the 

 normal. Thus, whereas the blood rarely contains more than i fig. of 

 aneurine per ml., detectable inhibition was produced by looo fig. per 

 ml. of serum. The authors conclude : " the possibility that thiamine 

 may be histologically localised in some tissue should be borne in mind, 

 for then it might exert its enzyme inhibition in vivo ". 



Aneurine appears to have a curious effect on acetyl choline. V. 

 Erspamer ^o observed that in vitro aneurine in concentrations greater 

 than 10 p. p.m. reduced the effect of acetyl choline on isolated tissues, 

 and that the intravenous injection into rats of 30 to 100 mg, per kg. 

 of bodyweight increased, and 100 to 500 mg. per kg. decreased, the 

 toxicity of sublethal doses of acetyl choline previously injected sub- 

 cutaneously. Moderate aneurine deficiency in pigeons enabled them 

 to resist the effect of twice the minimum fatal dose of acetyl choline, 

 and twice the usual concentration of acetyl choline was required to 

 stimulate the isolated gut of such pigeons. After the deficiency 

 symptoms had been cured by treatment with aneurine, the response 

 to acetyl choline was normal. The opposite effect was noted by 

 E. A. Zeller and H. Birkhauser ^^ in avitaminous rats, the liver of 

 which contained less choline esterase than normal, although the brain 



