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Re‐adaptation of the colonic mucosa following protracted stress in rats
Author(s) -
Rubio C. A.,
Hellström P.,
Sveander M.
Publication year - 2003
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1046/j.1365-2362.2003.01151.x
Subject(s) - dna , adaptation (eye) , dna synthesis , dna replication , thymidine , biology , medicine , endocrinology , genetics , neuroscience
Background We previously found that DNA synthesis of the colonic mucosa rises under protracted physical stress. At 8 stress weeks DNA values regained those of untreated animals, and was regarded as DNA adaptation to stress. Aims To assess whether the 8 weeks’ DNA adaptation to stress could be maintained following stress‐free intervals, ending with a stress stimulus. Methods Sixty rats were transported to the stress laboratory. Thirty were water plunged and 30 sham handled once a day, 5 days a week, for 8 weeks. After 8 stress weeks, groups of five animals were allowed to rest for 1, 2, 3 and 4 weeks, ending with single water plunging or sham handling. Five additional rats were untreated. All 65 animals received an i.p. injection of 3H‐thymidine before sacrifice. The ratio radioactive DNA/total DNA reflected the DNA synthesis of the colonic mucosa. Results Following DNA adaptation at 8 stress weeks, DNA replication in the right colon of the stressed rats significantly increased at 9, 10 and 11 weeks ( P < 0·05), but at 12 weeks it had decreased to 8‐week values. Conclusions DNA replication in the right colon of the stressed rats did not prevail: it increased considerably in the following weeks, but at 12 weeks (only 4 weeks later), re‐adaptation to DNA synthesis had occurred. The review of the literature indicates that this is the first report in which, following adaptation to protracted stress, a re‐adaptation phase to DNA replication is demonstrated in the colonic mucosa of experimental animals.