Chronic amitriptyline decreases autotomy following dorsal rhizotomy in rats.
In the rat, unilateral dorsal cervicothoracic rhizotomy (C5-T1), a proposed model of chronic pain, resulted in autotomy of the ipsilateral limb. The self-mutilation lesions were evaluated daily by means of an autotomy score from the 1st to the 80th postoperatory day. The onset of lesions was variable and attained the maximum degree 8-9 weeks after the dorsal roots section. Chronic administration of amitriptyline (5 and 10 mg/kg/day, i.p., over 30 days), started on the 10th day after rhizotomy, decreased autotomy behavior, an effect which persisted 20 days after treatment withdrawal, and lengthened almost two-fold the lag time between rhizotomy and appearance of lesions. A more pronounced effect was observed with the lowest dose of amitriptyline suggesting the existence of a therapeutic window. Possible mechanisms for the antinociceptive effect of amitriptyline in this model are discussed.
Abad
F
F
Department of Pharmacology, Faculty of Medicine, University of La Laguna, Tenerife, Spain.
Feria
M
M
Boada
J
J
D000639:Amitriptyline / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D012652:Self Mutilation / Q000188:drug therapy* / Q000503:physiopathology; D013116:Spinal Cord / Q000503:physiopathology*
D000929:Antidepressive Agents, Tricyclic; D000639:Amitriptyline