Abstract
The administration of nicotine during the perinatal stages of life resulted in a significant decrease in tumours occurring after transplacental induction by N-methylnitrosourea (MNU). The overall tumour incidence following p.o. application of MNU to dams was 85% in rats of the F1-generation, the main occurrence being related to the neurogenic system (62% of the animals). Regular injections of nicotine before or after birth resulted in a reduction of malignancies by 17% and 22% (P = 0.08 and 0.0015), respectively. The difference in the incidence of neurogenic tumours proved to be highly significant (P less than 0.002) in rats of either sex, when nicotine was applied over 26 weeks following birth. There was a gender-specific imbalance in rats which received the carcinogen only, in favour of a lower tumour yield in females (P less than 0.04), which became less apparent when nicotine was given additionally. These findings suggest that nicotine is capable of modulating the expression of chemically induced tumours of the neurogenic system in a favourable way.
Highlights
Significant differences, were observed with regard to the occurrence of the two main tumour types: 30% less females presented with neurogenic tumours (P
This study was designed to assess the influence of nicotine on the same carcinogen during the perinatal stages of life
No influence on tumour development was exerted by nicotine alone; this finding is in accordance with previously published data (Martin et al, 1979)
Summary
ChemicalsCommercially available nicotine tartrate was obtained from Serva (Heidelberg, FRG). Sixty male and 120 female Sprague Dawley rats were supplied at age 20 + 2 weeks by the Zentralinstitut fur Versuchstierzucht (Hannover, FRG). They were kept thereafter under conventional conditions (2 animals per Macrolon III cage, 22 + 2 C, relative humidity: 55 + 5%, dark-light rhythm: 12 h) and received Altromin pellets (diet 1320) and tap water ad libitum. Dams of groups 1, II and IV received 30mg MNU kg- 1 body wt by gavage (Acufirm 1.5 x 82mm) on day 20p.c. Nicotine (0.4mgkg -1) was administered s.c. to dams daily either before (days 14-20 p.c., groups II and III, respectively) or after birth (days 1-20 post partum, groups IV and V, respectively). The malignancy of the individual tumours was assessed by histological grading and by their potential to cause a life-threatening local expansion; all neurogenic tumours with the exception of tumours of the pituitary gland were subsumed to be malignant tumours
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