New technical approaches in stereotaxic catheterization of cerebral ventriculi: implications for the L-arginine/NO synthase/nitric oxide cascade.

In order to study the actions of certain substances at cerebral level, a stereotactic device for ensuring a precise catheterization of points in certain cerebral areas was used. For the operation technique was used a stereotaxic atlas specifically designed for rat brain (G. Paxinos, C. Watson, 1998), which offers all the necessary information for the identification of the trepanation. Stereotaxic implantation of cannules in the brain is useful for microinjecting solutions containing various substances (in amounts of microl), directly and targeted in the anatomical structures of the brain. The technique described can use either metalic or silastic cannules, that have variable lumen (usually for adapting a Hamilton syringe). The cannules can be implanted at cerebroventricular level, having the possibility to target all the cerebral ventricles. The intracerebroventricular (icv) administration of L-arginine induces a significant increase of response latency for mechano-algesic test. The most obvious changes are induced following the administration of the association of L-NAME with L-arginine, situation when is manifested an important increase of the response latency, starting with 5 minutes post-administration and continuing up to 45 minutes determination. The increase is significantly higher compared with the results obtained with L-arginine alone. A similar evolution is registered in the case of the plantar test.