Plasma hormone levels and the incidence of carcinogen-induced mammary tumours in two strains of rat

Abstract

Summary.-Three dihydrodiols that are metabolites of benzo [a] al., 1974) and the mechanism appears to be similar in mouse skin. Thus, spectrophotofluorimetric studies indicated that metabolism of the 7,8,9,10-ring was involved in the activation of benzo[a]pyrene in mouse skin (Daudel et al., 1975) and the chromatographic characteristics of the benzo[a]-pyrene-deoxyribonucleoside products that are formed in mouse skin treated with the hydrocarbon were recently found to be the same as those of the deoxyribonucleoside products that are formed when 7, 8-dihydro-7, 8-dihydroxybenzo[a]pyrene 9,10-oxide reacts with DNA in solution . This is in agreement with the general idea that the further metabolism of the olefinic double bonds present in non-K-region dihydrodiols can yield diol-epoxides (Booth and Sims, 1974) that react with DNA in vivo. The biological activity of non-K-region dihydrodiols in situations where they can be further metabolized is, therefore, of interest. Some non-K-region dihydrodiols are more active in the induction of malignant transformation in mouse fibroblasts than the parent hydrocarbons (Marquardt, Grover and Sims, 1976) and they can also induce more mutations, when metabolized by microsomal prepara-

Metabolism of Prolactin in Mice With a High Incidence of Mammary Tumours: Evidence for Greater Conversion Into a Non-Immunoassayable Form

“…For example, (a) plasma prolactin levels in breast cancer patients or in populations exposed to high risk of the disease are not conspicuously higher than those in control subjects (Boyns, Cole, Griffiths, Roberts, Buchan, Wilson & Forrest, 1973;Kwa, de Jong-Bakker, Engelsman & Cleton, 1974;Sheth, Ranadive, Suraiya & Sheth, 1975;Hill, Wynder, Kumar, Helman, Rona & Kuno, 1976;Kwa, Cleton, de Jong-Bakker, Bulbrook, Hayward & Wang, 1976), (b) about 86% of patients with idiopathic galactorrhoea have normal plasma prolactin levels (Kleinberg, Noel & Frantz, 1977) and (c) there is little correlation between milk yield and serum prolactin in cows (Koprowski & Tucker, 1973). The rat seems to be an apparent exception in that a positive correlation between plasma prolactin and the rate of tumour induction by a carcinogen has been demonstrated Hawkins, Drewitt, Freedman, Killin, Jenner & Cameron, 1976). Even in the rat, however, serious discrepancies between bioassay and RIA measurements of prolactin exist (see Nicoli, 1975 for review).…”

Prolactin levels and molecular heterogeneity in rat strains with high and low incidence of DMBA-induced mammary tumors

“…1). Mammary tumor incidence and growth have also been shown to be strain related in both of these species (2)(3)(4), and several studies have addressed the issue of strain differences in PRL secretion that may account for these mammary tumor differences. Sinha has most comprehensively studied PRL secretion in mice with variable incidence of mammary tumors (5)(6)(7)(8)(9).…”

Serum, pituitary and urine concentrations of prolactin and growth hormone in eight strains of mice with varying incidence of mammary tumors

“…Consequently, attempts have been made to correlate prolactin levels in blood with the incidence of the disease. In rats, Boyns et al (1973a) and Hawkins et al (1976) found a positive correlation between plasma levels of prolactin and the rate of mammary tumor induction by chemical carcinogens. Conflicting reports have appeared from similar studies in man.…”