Adaptation of the small intestine during pregnancy and lactation in the rat

Abstract

During pregnancy and lactation in the rat the small intestine in general and the mucosal epithelium in particular gain weight. The specific activities of sucrase, lactate dehydrogenase and succinate-tetrazolium reductase remain constant and those of glucose 6-phosphate dehydrogenase and isocitrate dehydrogenase increase. There is no evidence that the reported decrease in absorption per unit area or weight of mucosal epithelium during pregnancy and lactation is due to decreases in enzyme activities within the epithelium. The pattern of enzyme change shows that the response of the gut to the stimuli of pregnancy and lactation must be a complex one, possibly involving increases in the specific activities of some enzymes.

Integration of metabolism in tissues of the lactating rat

“…The activities of glucose 6-phosphate dehydrogenase (EC 1 .l .I .49) and isocitrate dehydrogenase (EC 1 .l .I .42) increase in the mucosal epithelium, whereas those of lactate dehydrogenase (EC 1 .l .1.27), succinate-tetrazolium reductase (EC 1.3.9.9) and sucrase (EC 3.2.1.26) do not change significantly [27]. Dipeptidases which are important for the final stages of protein digestion, are increased considerably in activity in the small intestine during lactation [28].…”

Activities of some metabolic enzymes in the small intestinal mucosa during pregnancy and lactation in the rat

“…These changes in total activity can be contrasted with the findings of Burdett, Green & Reek (1978) who studied a range of metabolic enzymes in different regions of the gut histochemically and reported some increases in activity during pregnancy but, in general, no further increases in lactation. Studies on some of the enzymes involved in energy production in the intestine by Burdett & Reek (1979) provide valuable complementary evidence. While specific activities of some enzymes were unchanged, others varied during the reproductive cycle and Burdett & Reek (1979) concluded that the response of the gut to the stimuli of pregnancy and lactation was complex.…”

“…Studies on some of the enzymes involved in energy production in the intestine by Burdett & Reek (1979) provide valuable complementary evidence. While specific activities of some enzymes were unchanged, others varied during the reproductive cycle and Burdett & Reek (1979) concluded that the response of the gut to the stimuli of pregnancy and lactation was complex. (Changes in the activity of NADP-dependent isocitric dehydrogenase, the only enzyme common to the two studies, were similar to those reported here.)…”

Activities of amino acid metabolizing enzymes in the stomach and small intestine of developing rats

“…The stomach and intestine play an important role in the post-prandial catabolism of some amino acids and a significant part in the inter-organ handling of amino acids in the whole splanchnic bed system (Aikawa et al, 19731. However, the enzymes of amino acid metabolism have been seldom studied (Burdett and Reek, 1979) After the animals were beheaded, they were dissected ; their stomach and small intestine were extracted, opened, cleaned of their contents, washed in saline, blotted, weighed and homogenized in chilled modified Krebs-Ringer bicarbonate buffer (Arola et al, 1978). Coarse homogenates were filtered through nylon mesh and used directly as an enzyme source.…”