Inflammation/metabolism; Neuralgia/metabolism; Nociceptors/metabolism; Peripheral Nervous System Diseases/metabolism; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide/metabolism; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Hyperalgesia/drug therapy; Hyperalgesia/metabolism; Hyperalgesia/physiopathology; Inflammation/drug therapy; Inflammation/physiopathology; Injections, Spinal; Ligation; Male; Neuralgia/drug therapy; Neuralgia/physiopathology; Neurons, Afferent/drug effects; Neurons, Afferent/metabolism; Nociceptors/drug effects; Nociceptors/physiopathology; Pain Measurement; Peptide Fragments/pharmacology; Peripheral Nerves/drug effects; Peripheral Nerves/metabolism; Peripheral Nerves/physiopathology; Peripheral Nervous System Diseases/drug therapy; Peripheral Nervous System Diseases/physiopathology; Pituitary Adenylate Cyclase-Activating Polypeptide/agonists; Pituitary Adenylate Cyclase-Activating Polypeptide/metabolism; Pituitary Adenylate Cyclase-Activating Polypeptide/pharmacology; Rats; Rats, Sprague-Dawley; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide/antagonists & inhibitors