Abstract
An optimal coordination between parents
and their offspring involves a sequence of
reciprocal behaviors to ensure the adequate
care of the young, which is critical for a healthy
physical, emotional, and social development.
Parental deprivation, particularly an impaired
child-mother attachment, induces lasting
changes in emotional as well as in cognitive
capacities in later life. We assessed in the South
American precocial species, Octodon degus,
whether alterations of glutamatergic function
of the limbic system induced by parental
deprivation may be a neural correlate for such
behavioral changes. Further, we analyzed
whether the mother's voice can protect from
separation-induced changes of brain function.
Changes of N-methyl-D-aspartate (NMDA)
receptor expression were examined in the
following three groups of 2-week-old Octodon degus
pups: (I) control animals who remained
undisturbed with the family; (II) animals who
were repeatedly separated from the family and
individually placed in an unfamiliar environment
for behavioral analysis (open field); and (III)
animals who were treated like the group described under (lI) but were presented with
maternal vocalizations during separation.
Relative to those in the control group I, the
animals in group II showed an upregulation of
NMDA receptor density in the (a)anterior
cingulate, prelimbic, infralimbic, and anterior
insular cortices; (b)CA1/stratum radiatum;
(c)CA1/stratum lacunosum moleculare and
CA3/stratum radiatum; and (d)in the basomedial
amygdaloid nucleus. Presentation of the
maternal call during the separation period
(group III) suppressed the separation-induced
NMDA receptor upregulation in all regions.
The results demonstrate that early life events
can influence the expression of transmitter
receptors and that maternal behavior, acting to
control the pup's socio-emotional environment,
is a key factor for regulating such developmental
events.