STUDY OF THE POSTNATAL EFFECTS OF CHEMOPREVENTIVE AGENTS ON ETHYLNITROSOUREA-INDUCED TRANSPLACENTAL CARCINOGENESIS IN RATS .2. INFLUENCE OFLOW-MOLECULAR-WEIGHT POLYPEPTIDE FACTORS FROM THE THYMUS, PINEAL-GLAND, BONE-MARROW, ANTERIOR HYPOTHALAMUS, BRAIN CORTEX AND BRAIN WHITE SUBSTANCE
Va. Alexandrov et al., STUDY OF THE POSTNATAL EFFECTS OF CHEMOPREVENTIVE AGENTS ON ETHYLNITROSOUREA-INDUCED TRANSPLACENTAL CARCINOGENESIS IN RATS .2. INFLUENCE OFLOW-MOLECULAR-WEIGHT POLYPEPTIDE FACTORS FROM THE THYMUS, PINEAL-GLAND, BONE-MARROW, ANTERIOR HYPOTHALAMUS, BRAIN CORTEX AND BRAIN WHITE SUBSTANCE, Carcinogenesis, 17(9), 1996, pp. 1931-1934
The influence of the polypeptide factors extracted from thymus, pineal
gland, bone marrow, anterior hypothalamus, brain cortex or brain whit
e substance on N-ethyl-N-nitrosourea (ENU)-induced transplacental carc
inogenesis was studied in rats, ENU was given to pregnant rats as a si
ngle i.v. exposure at a dose of 75 mg/kg body weight on the 21st day o
f gestation, The polypeptide factors were given to the offspring as a
series of s.c. injections, at a dose of 0.5 mg/rat/day, starting at on
e or 2.5 months of age and continuing throughout the whole of post-nat
al life, ENU induced tumors of the brain, spinal cord, peripheral nerv
es and kidneys in 94-98% of the offspring exposed to the carcinogen, w
ith an average number of 2.3-2.6 tumors per rat, and an average surviv
al time of 294 days, Post-natal thymus factor or pineal gland factor a
dministration was followed by an increase in mean lifespan of similar
to 2 months and a significant decrease (P < 0.05) in the total tumor n
umber per tumor-bearing rat, as well as the incidence and multiplicity
of spinal cord tumors, Pineal gland factor also decreased the inciden
ce of peripheral nerve and kidney tumors and their number per tumor-be
aring rat. Brain cortex factor and brain white substance factor treatm
ent was followed by a decrease in total tumor multiplicity of 1.2- to
3.3-fold, and a decrease in incidence of brain tumors of 10 to 33% per
rat in comparison to the controls, Brain cortex factor also decreased
the total tumor incidence, At the same time, brain white substance fa
ctor administration increased the incidence of peripheral nerve tumors
and decreased the mean lifespan, Both bone marrow factor and anterior
hypothalamus factor did not have any modifying effects on any of the
ENU-induced tumors and mean lifespan. Thus, our results show the possi
bility of attenuation of transplacental ENU-induced carcinogenesis wit
h post-natal administration of some polypeptide substances.