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Melatonin, and to a lesser extent growth hormone, restores colonic smooth muscle physiology in old rats
Author(s) -
Pascua Patricia,
CamelloAlmaraz Cristina,
Camello Pedro J.,
MartinCano Francisco E.,
Vara Elena,
FernandezTresguerres Jesus A.,
Pozo María J.
Publication year - 2011
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.2011.00904.x
Subject(s) - melatonin , endocrinology , oxidative stress , medicine , catalase , apoptosis , glutathione peroxidase , biology , inflammation , lipid peroxidation , biochemistry
There is increasing evidence that aging is associated with oxidative damage, inflammation, and apoptosis in different cell types. However, there is limited information regarding aging mechanisms in colon smooth muscle. Old male Wistar rats (22 months) were treated for 10 wks with melatonin or growth hormone (GH). Animals were sacrificed at 24 months of age by decapitation. The colon was dissected and the smooth muscle homogenized. H 2 O 2 and malonyl dialdehyde (MDA) content and catalase and glutathione peroxidase (GPX) activities were determined using colorimetric kits. Expression of nuclear factor kappa B (NF‐κB), cyclooxygenase 2 (COX‐2), caspase‐3, and caspase‐9 were determined by Western blot. Aging of colon smooth muscle correlated with an increase in H 2 O 2 and MDA levels when compared with young animals in both proximal and distal segments; these changes were associated with a decrease in the catalase activity in the distal colon. Oxidative stress correlated with an increase in COX‐2 and NF‐κB expression, which were accompanied by an enhanced expression of the pro‐apoptotic enzyme caspase‐3 and its upstream enzyme, caspase‐9. Melatonin treatment normalized the oxidative, inflammatory, and apoptotic patterns, whereas GH replacement, although effective in reducing oxidative stress in distal colon, did not reverse the age‐related inflammation or apoptosis. These results suggest that melatonin should be the treatment of choice to most effectively recover physiological functions in aged colonic smooth muscle.