title: Effect of continuous light on the incidence of 9,10-dimethyl-1,2-benzanthracene induced mammary tumors in female Holtzman rats.
abstract: The pineal has been recently implicated in mammary tumorigenesis. Effect of physiological pinealectomy brought about by subjecting female Holtzman rats to permanent lighting (24 h/day) from birth was studied on the incidence of 9,10-dimethyl-1,2-benzanthracene (DMBA) induced mammary tumors. The incidence of adenocarcinoma was 95% in animals maintained in continuous photoperiod in contrast to that (60%) observed in control animals maintained on a light/dark (10/14 h) schedule. Further, the latency period of tumor appearance (61.5 +/- 9 days) in the former group was found to be significantly shorter than that seen in the latter group (93.7 +/- 8.3 days). Explanations are offered for this difference in the observed incidence.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D001551:Benz(a)Anthracenes; D005260:Female; D008027:Light; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced*; D010870:Pineal Gland / Q000502:physiology* / Q000601:surgery; D011388:Prolactin / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001551:Benz(a)Anthracenes; D015127:9,10-Dimethyl-1,2-benzanthracene; D011388:Prolactin