Summary:
Objectives: The nervous system is a very sensitive system for early life
experiences. We
studied the basal forebrain cholinergic system (BFCS) in adult male rats, in
order to test
whether the T-maze learning experience (a novel early experience developed in
our lab)
affects the cholinergic system, which participates in cognitive functions,
including attention,
learning and memory.
Methods: Rat pups learn a T-maze during postnatal days 10-13 and either recieve
the
expected reward withough maternal contact (RER group) or are denied this reard
(DER
group). We determined immunohistochemically the levels of the synthesizing and
degrading
enzymes of acetylcholine, Choline-Acetyl-Transferase (ChAT) and
Acetyl-Cholinesterase
(AChE) in the primary cholinergic regions of the (BFCS).
Results: The number of ChAT positive cells was significantly reduced in DER
animals at the
complex of MS-VDB (medial septum- vertical limb of the diagonal band of Broca)
and HDB
(horizontal limb of the diagonal band of Broca) compared to both controls and
RER animals.
Regarding the AChE activity, we did not detect any significant differences with
the exception
of the basolateral
nucleus of amygdala (BLA) of the DER group, in comparison to both RER and
control groups.
Conclusions: The findings of the present study support the hypothesis that
training in a T-
maze task at the neonatal period under denial or receipt of expected reward
through maternal contact leads to long-term changes in the mesolimbic circuit
of the brain, especially in the BFCS, which may result in behavioral changes
even in adult life.
Keywords:
Cholinergic system, AChE, ChAT, Memory, Early experience
