EFFECTS OF 2 PROTEIN-FREE PEPTIDE DERIVATIVES ON PASSIVE-AVOIDANCE BEHAVIOR OF 24-MONTH-OLD

Cerebrolysin(R) is an aqueous protein-free solution produced by biotec hnological methods, using a standardised enzymatic breakdown of lipid- free pig brain proteins. The present study investigated the behavioura l effects of this peptide derivative PD (100 mg/kg b.wt.), a related e xperimental peptide derivative PD-exp (1 mg/kg b.wt.) and a 0.9% salin e control, on passive avoidance reaction (PAR) of 24-month-old male an d female rats. Rats were pre-treated chronically for 7 days. Passive a voidance procedure started one day after the last subcutaneous injecti on with a single PAR-acquisition training session. Animals were traine d in a step-through avoidance task using an unavoidable footshook of 1 mA (2 s). PAR-extinction testing showed that PAR latencies were treat ment dependent (p < 0.001) due to the fact that PD and PD-exp treated animals displayed better performance. The same was true for all other behavioural elements observed. In this study we were able to demonstra te that s.c, administration of PD and PD-exp changes the capability of old female but not of old male rats to extinguish step-through behavi our. Because there were no differences in postshock latencies between control females and males we propose different sensitivity for the sub stances used.