CAH patients have defective glycemic control and altered metabolic and hormonal responses during prolonged moderate-intensity exercise comparable to brisk walking.

The aim of this present study was to identify the earliest point at which riboflavin deficiency affects post-weaning bowel development in rats. After weaning, eighty Wistar rats were weightmatched as pairs, one animal being fed a normal synthetic diet and the other being fed the same diet but deficient in riboflavin. Body weight, feeding and rates of growth were monitored and eight pairs of animals were taken for analysis at 45, 69, 93, 117 and 141 h. Riboflavin status was monitored by determining the erythrocyte glutathione reductase activation coefficient (EGRAC), and hepatic flavins were measured by a fluorescence assay. Changes to the number and dimensions of villi and crypts in the duodenum were determined, as well as crypt division (bifurcation) and the DNA synthesis index of the crypt epithelium by bromodeoxyuridine (BrdU) labelling. Riboflavin deficiency was established in the experimental rats, as demonstrated by a significant increase in EGRAC after 45 h (P,0 : 001) and decreased liver flavins after 96 h (P,0 : 001). After 96 h a significant increase in the size and cellularity of the crypts (P,0 : 001 in both cases) was seen in these riboflavin-deficient animals, with a decreased incidence of bifurcating crypts and of BrdU-labelled cells. No changes to villus number or size were observed. The present study has demonstrated that developmental changes to the duodenal crypt arise shortly after circulating riboflavin measurements show evidence of deficiency. These changes primarily affect cell proliferation and crypt bifurcation, and precede long-term changes such as the reduction of villus number.

Summary1. Aqueous extracts of stratum corneum were found to cause histamine-like contractions of the guinea-pig ileum which were not antagonized by mepyramine, atropine or bromolysergic acid diethylamide. 2. The compounds responsible for this contraction were isolated by chromatography and shown to be common amino acids, particularly L-serine and L-alanine which occur in abundance in the stratum corneum. 3. Amino acid analogues were assayed on the guinea-pig ileum against alanine as standard. With the exception of y-amino butyric acid and L-alanine benzyl ester all analogues which had appreciable activity gave dose-response curves parallel to L-alanine. 4. The response to L-alanine benzyl ester was abolished by mepyramine and this analogue appears to be a partial agonist on the histamine receptor. 5. The effects of substitution on the equipotent molar ratios of amino acid analogues indicate that all four chemical groups attached to the a-carbon of L-alanine interact with the receptor. 6. Our results suggest that the guinea-pig ileum contains an L-a-amino acid receptor.

An increase in the size and cellularity of duodenal crypts and a decreased incidence of bifurcating crypts is observed in response to very short-term feeding of a riboflavin-deficient diet to weanling rats. A study was conducted to determine whether the absence of riboflavin in the lumen of the small intestine impairs gastrointestinal development. Forty-eight female weanling Wistar rats were allocated to one of two treatment regimens, to receive either a riboflavin-deficient diet and a daily intraperitoneal injection of flavin mononucleotide (luminally deficient group) or a complete diet and a daily intraperitoneal injection of saline (control group). Animals were killed at 93, 141, or 165 hr from feeding. The flavin injection regimen maintained normal systemic riboflavin status in the luminally deficient group. In this group, however, crypt hypertrophy and reduced crypt bifurcation were evident by 141 hr of luminal riboflavin deprivation. The absence of riboflavin in the duodenal lumen impairs normal development, suggesting that a crypt sensing mechanism may be involved in the response to riboflavin deficiency.