Lateralized and compulsive exteroceptive orientation in rats treated with apomorphine

Area of Science:

• Neuroscience
• Behavioral Pharmacology

Background:

• Dopamine (DA) plays a crucial role in motor control and motivated behaviors.
• Lateralization of brain function is observed in various species, including rodents.
• Understanding drug-induced behavioral lateralization can provide insights into brain asymmetry.

Purpose of the Study:

• To investigate the lateralizing effects of the dopamine receptor agonist apomorphine (APO) on novel behavioral tasks in rats.
• To determine if APO-induced behavioral lateralization is associated with specific brain mechanisms.

Main Methods:

• A new behavioral test was developed to assess taxis for edges.
• Rats were treated with apomorphine (1.25 mg/kg, s.c.).
• Locomotor direction was measured using a rotometer.

Main Results:

• Apomorphine induced compulsive and highly lateralized edge-taxis in 16% of rats.
• Apomorphine induced lateralized locomotor direction in 29% of rats.
• The lateralizing effects on edge-taxis and rotation were not reliably associated.

Conclusions:

• Apomorphine exhibits distinct lateralizing effects on different behaviors in subpopulations of rats.
• These findings suggest that APO-induced lateralization of edge-taxis and rotation are independent processes.
• Interhemispheric dopamine receptor asymmetries in distinct brain regions may underlie these diverse effects.