Activity-dependent reduction of dopamine D2 receptors during a postnatal critical period of plasticity in rat striatum is not affected by prenatal haloperidol treatment.

Motor activity induced in the Circling Training test (CT) during a postnatal (PN) critical period of plasticity (PN30-37) produces a long-lasting decrease in the number of binding sites and mRNA expression levels of the dopamine D2 receptor (D2R) in rat striatum. Prenatal exposure to the antipsychotic haloperidol also decreases postnatal levels of the striatal D2R in the offspring. We examined whether such fetal exposure to haloperidol could affect the activity-dependent reduction of the D2R system during the critical period.

Developmental striatal critical period of activity-dependent plasticity is also a window of susceptibility for haloperidol induced adult motor alterations.

Experience-dependent plasticity during critical periods of postnatal (PN) development shapes the adult brain anatomy and function. In rat motor system, there is a critical period of activity-dependent plasticity in the striatum (PN30-37). In this period, motor activity of running in a circular path induced in the Circling Training test (CT), elicits several plasticity changes on striatal synapses.

Permanent motor activity and learning disorders induced by exposure to phenytoin during gestation and early infancy in the rat.

Experimental models and clinical data indicate that the incidence of motor and learning disorders may be increased in children of epileptic mothers taking phenytoin (PHT) during pregnancy. There is little data on the vulnerability of infants to PHT-induced long-term behavioral toxicity after gestational or early life exposure (i.e.

Postnatal haloperidol eliminates the deficit in circling behavior produced by prenatal exposure to the same drug.

Up to 35% of pregnant women take psychotropic drugs at least once during gestation [Austin and Mitchell, 1998]. From concurrent animal and human evidence, it has been proposed that exposure to several psychoactive medications in utero or during lactation increases the risk for permanent brain disorders. Present preventive or therapy practices applied on humans for this type of long-lasting behavioral alterations are mainly based on empirical results.

Different dopamine D1 and D2 receptors expression after motor activity in the striatal critical period.

Circling training during rat striatum postnatal critical period (PN30 to 37 days) induces a life-lasting co-reduction of muscarinic acetylcholine receptors (mAChR) and dopamine D2 receptors (D2R) binding. Here, we evaluated the expression of D1R and D2R under similar experimental conditions. Trained rats showed a decrease of 40% in D2R binding sites (p<0.

Delayed and bilateral changes of GAP-43/B-50 phosphorylation after circling training during a critical period in rat striatum.

During the critical period of activity-dependent plasticity in rat striatum (30-37 days after birth) physiological circling behavior induces delayed modifications in GAP-43/B-50 phosphorylation by PKC. Postexercise, ipsi- and contralateral striatum to the circling direction show a similar temporal pattern of GAP-43/B-50 phosphorylation, with an initial decrease followed by a subsequent increase. However, there is a lag between initiation of the phosphorylation response in this asymmetrical task which does not occur when animals are subjected to exercise under conditions of symmetrical motor activity.