Effects of an anti-beta-endorphin serum on tonic immobility in rabbits.
The involvement of endogenous beta-endorphin (beta-EP) in tonic immobility (TI) was evaluated in rabbits following the intracerebroventricular (ICV) administration of a specific antibody. Rabbits were tested twice with a 1-week intersession interval. For each animal, results of Session 1 were used as the baseline. Six hours before the beginning of Session 2, a bilateral ICV injection of specific anti-beta-EP serum or aspecific gamma-globulin (vehicle) was performed. Results showed that pretreatment with anti-beta-EP serum increased TI duration, whereas no change occurred in the vehicle group. In a parallel experiment we evaluated TI duration in the presence of formalin pain: TI increased in animals pretreated with aspecific gamma-globulins and decreased in the animals pretreated with anti-beta-EP serum. Results suggest that the beta-EP system acts to limit TI duration, but that this effect is reversed by persistent pain.
Aloisi
A M
AM
Instituto di Fisiologia Umana, Università degli Studi di Siena, Italy.
Panerai
A E
AE
Carli
G
G
D000818:Animals; D000906:Antibodies / Q000008:administration & dosage / Q000502:physiology*; D005557:Formaldehyde; D007276:Injections, Intraventricular; D008297:Male; D009068:Movement / Q000187:drug effects / Q000502:physiology*; D010147:Pain Measurement / Q000187:drug effects; D011817:Rabbits; D001615:beta-Endorphin / Q000276:immunology*; D005719:gamma-Globulins / Q000008:administration & dosage / Q000494:pharmacology
D000906:Antibodies; D005719:gamma-Globulins; D005557:Formaldehyde; D001615:beta-Endorphin