title: Effect of prolonged psychoemotional stress and melatonin on experimental mammary carcinogenesis in female rats.
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 microg/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.
authors: Department of Animal Physiology, P.J. Safárik University, Kosice.
authors: M
authors: M
authors: Kassayová
authors: L
authors: L
authors: Friedmanová
authors: P
authors: P
authors: Orendás
authors: P
authors: P
authors: Kubatka
authors: B
authors: B
authors: Bojková
authors: N
authors: N
authors: Bobrov
authors: E
authors: E
authors: Ahlersová
authors: I
authors: I
authors: Ahlers
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000627:therapeutic use*; D002273:Carcinogens / Q000633:toxicity; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control*; D008550:Melatonin / Q000627:therapeutic use*; D008770:Methylnitrosourea / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological
chemical_list: D000975:Antioxidants; D002273:Carcinogens; D008770:Methylnitrosourea; D008550:Melatonin