Analgesia/methods; Avoidance Learning/physiology; Cannabinoid Receptor Modulators/metabolism; Endocannabinoids; Neural Inhibition/physiology; Pain/metabolism; Receptors, Opioid/metabolism; Amidohydrolases/antagonists & inhibitors; Amidohydrolases/metabolism; Amygdala/drug effects; Amygdala/metabolism; Animals; Arachidonic Acids/metabolism; Avoidance Learning/drug effects; Benzamides/pharmacology; Carbamates/pharmacology; Conditioning, Psychological/drug effects; Conditioning, Psychological/physiology; Enzyme Inhibitors/pharmacology; Extracellular Signal-Regulated MAP Kinases/drug effects; Extracellular Signal-Regulated MAP Kinases/metabolism; Fear/drug effects; Fear/physiology; Male; Narcotic Antagonists/pharmacology; Neural Inhibition/drug effects; Pain/drug therapy; Pain/physiopathology; Pain Measurement; Polyunsaturated Alkamides/metabolism; Rats; Receptor, Cannabinoid, CB1/antagonists & inhibitors; Receptor, Cannabinoid, CB1/metabolism; Receptors, Opioid/drug effects; Signal Transduction/drug effects; Signal Transduction/physiology