Stress of chronic food restriction attenuates the development of adjuvant arthritis in male Long Evans rats
Abstract
To study the effect of the stress of chronic food restriction on the development of adjuvant arthritis in Long Evans male rats. METHODS: Four groups of animals were compared: non-treated control (C) and arthritic (AA) rats, both with free access to food and water and two analogous groups with a 40% food restriction, i.e. non-treated (FR) and arthritic (AA-FR) animals.
All rats were killed 22 days following the injection of complete Freund's adjuvant. The parameters measured were: serum levels of albumin (ALB), nitrate, glucose, insulin, corticosterone (CORT), prolactin (PRL) and PRL mRNA in the adenopituitaries.
In addition the activity of gamma-glutamyl transpeptidase (GGTP) was measured in the spleen. The pain threshold was determined by the tailflick method.
The body weight of the animals was recorded on day 0, 3, 7, 11, 15 and 18 of the disease. RESULTS: Arthritis caused swelling of the hind paw (2.37 +/- 0.15 ml vs 1.1 +/- 0.05ml in controls, p < 0.01) which was prevented in the AA-FR group (1.44 +/- 0.13 ml, not significant against controls).
Arthritis increased serum NO and reduced ALB levels; both changes were significantly restored in the FR-AA group. Food restriction did not alter the activation of GGTP, or the decrease of PRL mRNA observed in the AA group.
Serum CORT was elevated in rats with food restriction (15.49 +/- 2.1 vs. 3.7 +/- 0.87 microg/dL) and remained enhanced to the same extent in AA and FR-AA groups. The tailflick latency prolonged in the AA group was reduced by food restriction.
CONCLUSION: These results show that 40% food restriction associated with elevated CORT levels mitigated the inflammatory parameters activated during AA.