Effects of the LHRH antagonist Cetrorelix on affective and cognitive functions in rats

The decapeptide LHRH antagonist, Cetrorelix, inhibits gonadotropin and sex-steroid secretion. Cetrorelix is used for IVF-ET procedures and for the treatment of benign prostatic hyperplasia, endometriosis and leiomyomas. However little is known about the effects of Cetrorelix on brain functions. Previously we have tested Cetrorelix in mice on the impairment of the consolidation of a passive avoidance behavior caused by beta-amyloid 25–35, anxiolytic action in the plus-maze, antidepressive action in a forced swimming test, tail suspension and open-field behavior following its administration into the lateral brain ventricle. In the present study we repeated and extended the experiments in rats in order to determine whether there are species differences in the action of Cetrorelix between mice and rats. The effects of Cetrorelix evaluated included the methods used in mice without tail suspension test and extended by measuring core temperature. Cetrorelix fully blocked the impairment of the consolidation of passive avoidance learning when given icv 30 min following administration of beta-amyloid 25–35. If beta-amyloid 25–35 and Cetrorelix were given simultaneously, Cetrorelix was ineffective. Cetrorelix elicited slight anxiogenic and stronger anxiolytic action in the plus-maze, depending on the dose used. In the forced swimming tests, Cetrorelix showed antidepressive-like action. In open-field behavior tests Cetrorelix displayed a U-type action on locomotion with 0.5 and 2 µg increasing locomotion, and increase rearing but and had no effect on grooming at 0.5–2 µg. Cetrorelix had no action on core temperature. Our findings demonstrate that Cetrorelix is able to correct the impairment of the memory consolidation caused by beta-amyloid 25–35. Cetrorelix elicits anxiolytic and antidepressive action, slightly increases locomotion and rearing in open field, but it does not influence the core temperature. The results obtained in rats are similar to those reported previously by us in mice. Collectively our findings confirm the effects of Cetrorelix on brain function in two species and suggest the possible merit of a clinical trial with Cetrorelix in patients with anxiety, depression and Alzheimer's disease.