Parallel anxiolytic-like and antinociceptive actions of diazepam in the anterior basolateral amygdala and dorsal periaqueductal gray.
BACKGROUND
The antinociceptive actions of diazepam and other benzodiazepines are partly due to their anxiolytic-like properties.


OBJECTIVE
This study was conducted to analyze the relationship between the anxiolytic-like and antinociceptive effects of diazepam when injected into the anterior basolateral amygdala (ABLA) and the dorsal periaqueductal gray (dPAG). These areas were selected because of their important participation in the regulation of anxiety and defensive responses.


METHODS
The anxiolytic-like effect of diazepam was evaluated with the rat burying behaviour test. The pain-induced functional impairment in the rat (PIFIR) model was used to study the effects of diazepam on nociception. Nociception was induced by intra-articular injection of 15% uric acid into the knee joint of the right hind limb.


RESULTS
Sole exposure to the burying behaviour test produced a slight non-significant hyperalgesic effect. Diazepam injection (2.0 microg/0.4 microl) into the ABLA or dPAG produced a reduction in cumulative burying behaviour--an anxiolytic-like effect--together with an increase in burying behaviour latency. Such reduced experimental anxiety was paralleled by an antinociceptive response (i.e., increased use of the uric-acid-injected limb). Reduced experimental anxiety was correlated with antinociception after diazepam infusion into both brain structures.


CONCLUSIONS
Diazepam-reduced experimental anxiety was paralleled by antinociceptive effects.
Jiménez-Velázquez
Guadalupe
G
Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Sede Sur, Calz. de los Tenorios 235, Col. Granjas Coapa, C.P. 14330, México D.F., Mexico.
López-Muñoz
Francisco Javier
FJ
Fernández-Guasti
Alonso
A
D000679:Amygdala / Q000187:drug effects*; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001007:Anxiety / Q000188:drug therapy*; D019540:Area Under Curve; D001522:Behavior, Animal / Q000187:drug effects; D003975:Diazepam / Q000494:pharmacology*; D004195:Disease Models, Animal; D008297:Male; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy*; D010487:Periaqueductal Gray / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D018709:Statistics, Nonparametric; D014527:Uric Acid / Q000009:adverse effects
D014151:Anti-Anxiety Agents; D014527:Uric Acid; D003975:Diazepam