RATIONALE: Mechanisms and brain substrates mediating cannabinoid-induced modulation of behaviour towards aversive stimuli are poorly understood. OBJECTIVES: To investigate the effects of systemic and intra-dorsal periaqueductal grey (PAG) administration of the cannabinoid receptor agonist @entity10025 on behaviour and plasma @entity2819 levels in @entity35 exposed to ultrasound and determine the contribution of CB(1) receptors. METHODS: In experiment 1, @entity35 received vehicle or CB(1) receptor antagonist @entity351 (3 mg/kg, IP) 30 min prior to a second injection of vehicle or @entity10025 (5, 20 or 80 microg/kg, IP). In experiment 2, @entity35 received intra-dorsal PAG vehicle or @entity351 (30 microg/ @entity35 ) 10 min prior to intra-dorsal PAG vehicle or @entity10025 (5 microg/ @entity35 ). Following injections, @entity35 were exposed to an aversive 20 kHz ultrasonic tone for 3 min. Behaviour, including hyperlocomotor activity and freezing, was monitored during and post-ultrasound. Plasma @entity2819 levels 10 min post-ultrasound were measured. RESULTS: Ultrasound induced explosive running and freezing behaviour. Systemic administration of @entity10025 attenuated the expression of ultrasound-induced hyperlocomotor activity and increased freezing. The @entity10025 -induced @entity536 was blocked by @entity351 . Intra-PAG administration of @entity10025 reduced the expression of ultrasound-induced hyperlocomotor activity, an effect not blocked by @entity351 . Systemic and intra-PAG administration of @entity10025 increased plasma @entity2819 levels, an effect not blocked by @entity351 . CONCLUSIONS: The cannabinoid receptor agonist @entity10025 modulates behaviour towards an aversive ultrasound stimulus in @entity35 , an effect accompanied by @entity101 activity. These effects may be mediated, at least in part, by the dorsal PAG but cannot be explained solely by an action at CB(1) receptors.

Cannabinoids modulate ultrasound-induced aversive responses in XXXX .

@entity10025 :: ('MESH:C062018', 'Chemical') :: ['HU210'] @entity101 :: ('MESH:D006973', 'Disease') :: ['increased HPA axis'] @entity2819 :: ('MESH:D003345', 'Chemical') :: ['corticosterone'] @entity536 :: ('MESH:C538265', 'Disease') :: ['attenuation of hyperlocomotor activity'] @entity35 :: ('10116', 'Species') :: ['rat', 'rats'] @entity351 :: ('MESH:C089032', 'Chemical') :: ['SR141716A']
@entity35 :: (10116,Species) :: ['rats']
