Neoplasma Vol.54, p.251-255, 2007
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Title: Effect of prolonged psychoemotional stress and melatonin on experimental mammary carcinogenesis in female rats |
Author: M. KASSAYOVA, L. FRIEDMANOVA, P. ORENDAS, P. KUBATKA, B. BOJKOVA, N. BOBROV, E. AHLERSOVA, I. AHLERS |
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Abstract: The aim of the present study was to determine whether prolonged stress – repeated immobilization in boxes during the period of 18 weeks (IMS) influenced development and progression of N-methyl-N-nitrosourea (NMU)-induced mammary tumors in female Sprague-Dawley rats and whether long-term MEL application affected changes caused by stress. NMU was applied intraperitoneally in two doses each of 50 mg/kg b.w. between 40 – 50 postnatal days. Melatonin (MEL) was administered in drinking water in a concentration of 4 μg/ml (daily from 3 p.m to 8 a.m), application was initiated 3 days prior to first NMU dose and lasted until the end of the experiment. Immobilization (2 h/day) began on the fifth day after second carcinogen application, animals were immobilized three times a week. Repeated immobilization of rats during 18 weeks decreased tumor frequency per group and per animal by 30% and tumor volume gain by 16% as opposed to control (NMU) animals. Combination of repeated immobilization and a long-term MEL application lowered incidence by 13% when compared to control, prolonged latency by 13%, decreased tumor frequency per group (by 44%) and per animal (by 35%). Tumor volume gain increased by 35% but their cumulative volume prominently decreased by 74% as opposed to control. Tumor volume was the most markedly influenced by MEL, induced tumors developed more rapidly – tumor volume gain increased by 61%. However, their cumulative volume markedly decreased by 75% when compared to immobilized group drinking water. Prolonged stress inhibited development and progression of NMU-induced mammary gland tumors in female rats and this effect was enhanced by long-term melatonin administration.
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Keywords: prolonged immobilization stress, mammary carcinogenesis, melatonin, rat |
Year: 2007, Volume: 54, Issue: |
Page From: 251, Page To: 255 |
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