Alterations of beta-endorphin-like immunoreactivity in CSF following behavioral training using a passive avoidance procedure.
The central opioid system may have an important influence on memory processes. In view of this, the concentration of beta-endorphin-like immunoreactivity (beta-ELIR) in cerebrospinal fluid (CSF) was measured by a radioimmunoassay in rats trained in a passive avoidance procedure. The beta-ELIR in CSF was examined immediately, 2, 5, 10, and 30 min after the learning trial in which rats were exposed to footshock (0, 0.25, or 1.0 mA for 3 s). Avoidance latency and beta-ELIR in CSF were examined 24 and 120 h after the learning trial. The beta-ELIR in CSF was increased at 5 min after the learning trial in rats exposed to footshock of 0.25 mA. The beta-ELIR in CSF was elevated at 5 and 10 min, followed by a significant decrease at 30 min after the learning trial in rats exposed to a footshock of 1.0 mA. Thus, although an increase in beta-ELIR in CSF was not, the duration of the increase was, related to the shock intensity. Interestingly, a decrease followed the increase in beta-ELIR in CSF which was significant only in rats exposed to the high shock intensity. Avoidance latencies were enhanced in a shock intensity-dependent manner at both 24 and 120 h retention tests. No change in beta-ELIR in CSF was found during retention trials. The results suggest that behavioral manipulations alter beta-ELIR in CSF. An increase in beta-ELIR in CSF may be highly associated with stressful and emotional responses during behavioral training.
Wan
R Q
RQ
Rudolf Magnus Institute for Neurosciences, Department of Medical Pharmacology, Utrecht, The Netherlands.
Wiegant
V M
VM
de Jong
W
W
de Wied
D
D
D000818:Animals; D001143:Arousal / Q000502:physiology*; D001245:Association Learning / Q000502:physiology; D001362:Avoidance Learning / Q000502:physiology*; D001521:Behavior Therapy; D001921:Brain / Q000502:physiology; D004597:Electroshock; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000502:physiology; D012153:Retention, Psychology / Q000502:physiology; D001615:beta-Endorphin / Q000134:cerebrospinal fluid*
D001615:beta-Endorphin