[Long-term effects of substance P on the higher nervous activity of primates]

The conditioned reflex, blood pressure and behavioral parameters prior to and during a single application of Substance P to unnarcotized primates were tested on four successive days, as well as of physiological saline also administered as a single application on four successive days. The evaluations were done each after 24 h from application. In a dose range from 0.25-25 micrograms/kg b.wt. the drug improved the performance of the conditioned reflex, while at 250 micrograms/kg b.wt. no improvement was ascertainable. At high doses behavioral disorders occurred. Blood pressure values showed no detectable reactions. From 25 micrograms/kg b.wt. onwards the application produced distinct immediate vegetative reactions which, however, subsided still during the 4-day procedure. At 250 micrograms/kg b. wt., the vegetative reactions became increasingly stronger. It is concluded that the individual functional circuits of the organism respond differently to Substance P. Behavioral reactions occurring 24 h after the application were not considered to be direct effects of Substance P. It is assumed that Substance P gives a push to other neuroactive systems.