DOES EARLY MATERNAL ENVIRONMENT MODIFY GENETICALLY DETERMINED
ABNORMALITY IN PUBS BEHAVIOR?
Olga I. Petrenko
Laboratory of Evolutionary Genetics,
Institute of Cytology & Genetics, Novosibirsk, Russia
In contrast to a strong tendency
to consider a common environment as the major cause of the
parent-offspring similarity in humans, the animal behavior
genetics seems to be more tolerable to the purely genetic
interpretations of such similarity. However, there is some
evidence indicating that, even in the case of animals, the
nature-nurture dichotomy is not so simple. The findings of
long-lasting effects of challenge in maternal environment
on adulthood behavior may revise the traditional concept of
the predominance of genetic factors in determination of animal
character. In the present research, I studied the influence
of changes in maternal environment by-fostering and cross-fostering
on such a behavior abnormality as genetically determined predisposition
to enlarged cataleptic reaction in rats. This abnormality
is of interest for our group, because we assume that it might
serve as a possible animal model of biological basis for a
special psychopathological condition similar to that in humans
(Kolpakov et al., 1996).
Two rat strains - GC bred from a
Wistar stock for the predisposition to catalepsy (Barykina
et al., 1983), and the control Wistar stock - were used as
the experimental animals. The items of natural and foster-mothers`
nursing behavior were studied according to Myers et al. (1989).
The pinch-induced catalepsy of the offspring was tested at
the age of 2 weeks. In order to elucidate the influence of
the main studied factors (genotype vs. type of fostering)
and their interaction, the data were analyzed by means of
two-way ANOVA with genotype and type of fostering as the main
Reciprocal pup substitution (cross-fostering)
to GC and Wistar females showed the attenuation of cataleptic
predisposition in GC rats fostered by Wistar foster-mothers
that demonstrate more intense maternal care than GC mothers.
A significant negative correlation was found between the frequency
of mother return to the nest and the duration of pinch-induced
catalepsy. In the home cage retrieval test of the females
of the compared strains showed significant dependence of the
latencies of approach to, and retrieval of the pups from the
genotype (either their own or the adopted pups` genotype).
The results suggest that the expression
of catalepsy seems to be dependent not only upon the genetic
predisposition as earlier was shown by Kolpakov et al. (1999),
but also upon the maternal environment. Thus, the abnormality
of behavior can be corrected to some extent by the mother's
behavior. The maternal environment is an essential part of
ontogenetic niche till weaning, and it may be considered as
an envelope of deploying the intrinsic genetic program throughout
the first period of life. The obtained data indicate that
the attenuation of cataleptic predisposition found in GC rats
nursed by Wistar foster-mothers might be caused by better
nursing of the Wistar foster-mothers of the adopted GC pups
compared to the nursing of the biological mothers. It is possible
that the predisposition to catalepsy includes the elements
of anaclitic depression known in humans.
Conclusion and application
These data are in accordance with
several other studies suggesting that the changes of maternal
environment can modify in a specific way the influence of
some genetically determined behavioral characteristics, i.
e. mother behavior can correct certain inherited abnormalities.
Besides, these results support earlier evidence of the importance
of interaction between mother and her children for the development
of normal children's mentality. This is especially true for
human as the most social (eusocial) mammals.
This project was carried out at the
Institute of Cytology & Genetics under supervision of Viktor
Georgievitch Kolpakov, Doctor of Science. I also thankful
to T.A. Alekhina, N.N. Barykina, and V.F Chuguy for the support
of this research.