Striatal Level of Regulation of Learned Forepaw
Movements in Rats
I. A. ZHURAVIN, N. M. DUBROVSKAYA, S. A.
PLESNEVA
Sechenov Institute of Evolutionary Physiology and Biochemistry,
Russian Academy of Sciences, St. Petersburg, Russia
Summary
The role of the striatal adenylyl cyclase (AC) and cholinergic
systems in the learning and expression of new forepaw movements
(reaching with prolonged pushing on a fixed piston) was studied
in male Wistar rats. Motor learning processes, prenatal hypoxia,
and cholinergic drugs changed the properties of the AC system in
the striatum. After learning, the striatal basal AC activity was
decreased compared to untrained control rats. In addition, the
AC activity was more decreased in animals with a good ability to
learn compared to poor learners (up to 31 % and 51 %,
correspondingly; p<0.01). Rats subjected to prenatal hypoxia
(13-14th days of embryogenesis) had a lower ability to learn the
new movements requiring tactile control and the striatal AC
activity in these rats was 1.8 times higher (p<0.001) than
controls. In vitro application of the cholinergic agonist
carbachol (CARB) 10-5 M (corresponding to ~ 0.3 g), as well as
the antagonist scopolomine (SCOP) 10-5 M (~ 0.3 g) decreased AC
activity in the synaptosomal fraction of the striatum. In vivo
injections of CARB (0.3-3 g/1l) or SCOP (0.3-3 g/1l) into
the ventral striatum (nucleus accumbens) modified the newly
learned sensorimotor skill. After CARB injections the rats
performed slower movements with more prolonged pushing. After
SCOP the rats could not retain the learned pushing movement.
These in vivo and in vitro data suggest that the cholinergic
mediator system of the striatum is involved in learning
sensory-controlled forepaw movements as well as the regulation
of new motor skills by modulating the AC signal transduction
process in the striatum. The data confirmed that modification of
the striatal AC system resulted in the modulation of reaching
behavior and better expression of the learned reflex.
Key
words
Striatum • Cholinergic systém • Adenylyl cyclase • Learning •
Reaching movement • Rat
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Dr. Igor A. Zhuravin, PhD, DSc., Head of the Department of the
Comparative Physiology and Pathology of the CNS,
Institute of Evolutionary Physiology and Biochemistry, RAS.
M.Thorez av., 44, 194223, St.Petersburg, Russia.
Tel.: 7(812)5523166; Fax.: 7(812)5523012. e-mail:
zhuravin@iephb.ru
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