Allylamine and β-aminopropionitrile induced aortic medial necrosis: mechanisms of synergism

• Published in: Toxicology (Amsterdam) 1998-02, Vol.125 (2-3), p.107-115
• Main Authors: Kumar, D, Trent, M.B, Boor, P.J
• Format: Article
• Language: English
• Subjects: Allylamine; Allylamine - toxicity; Aminopropionitrile - toxicity; Analysis of Variance; Animals; Aorta - drug effects; Aorta - pathology; Aortic smooth muscle; Biological and medical sciences; Blood and lymphatic vessels; Body Weight - drug effects; Cardiology. Vascular system; Diet; Diseases of the aorta; Drug Synergism; l-Cysteine; Male; Medical sciences; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - pathology; Necrosis; Phenelzine; Rats; Rats, Sprague-Dawley; Semicarbazide; Survival Rate; Vascular media; β-aminopropionitrile
• ISSN: 0300-483X; 1879-3185
• DOI: 10.1016/S0300-483X(97)00168-6

We have developed a model of aortic smooth muscle necrosis in adult Sprague Dawley rats by feeding them two vascular toxins (allylamine HCl, or AA, and β-aminopropionitrile, or βAPN) in concert for 10 days. Either toxin given alone does not cause aortic lesions. In order to shed light on the mechanism of the synergistic action of these two toxins we fed known modulators of AA or βAPN toxicity to rats concurrently with the two toxins. As modulators we used (a) semicarbazide (98 mg/kg/day, given 4 h prior to toxins), a known inhibitor of the vascular enzyme SSAO which metabolizes AA; (b) l-cysteine (1.5% in rat chow, beginning 3 days prior to toxins), which has been shown to reduce the toxic effects of βAPN; and (c) phenelzine sulphate (3 mg/kg/day, given 4 h prior to toxins), an inhibitor of SSAO and potentiator of βAPN toxicity. Rats were fed various combinations of the toxins and modulators by gavage: water (n=8); (AA, 100 mg/kg/day) AA+phenelzine (n=8); AA+semicarbazide (n=8); AA+l-cysteine (n=11); (βAPN, 1 g/kg/day) βAPN+phenelzine (n=8); βAPN+semicarbazide (n=8); βAPN+l-cysteine (n=8); (AA, 100 mg+βAPN, 1 g/kg/day) AA+βAPN+phenelzine (n=9), AA+βAPN+semicarbazide (n=8); AA+βAPN+l-cysteine (n=12); phenelzine (3 mg/kg/day) (n=4); semicarbazide (98 mg/kg/day) (n=4) and l-cysteine (1.5% in rat chow) (n=4). We found that phenelzine sulphate (a drug previously used in the treatment of hypertension) when given with AA reproduced the AA+βAPN induced aortic lesions. Phenelzine+βAPN caused no lesions, but when combined with AA+βAPN, aortic lesions were intensified and included marked secondary degeneration of the vascular wall. Semicarbazide was found to completely obviate the vascular toxicity of AA+βAPN. l-Cysteine feeding markedly decreased the incidence and severity of vascular lesions in AA+βAPN treated rats, but did not change the incidence or severity of heart lesions caused by AA alone. These data indicate that the synergistic necrotizing toxicity of AA+βAPN is primarily an AA effect. We postulate that some modulating influence of βAPN (or phenelzine) on tissue distribution, metabolism, or detoxification pathways of AA increases AA's acute vascular toxicity, whereas semicarbazide offers protection by inhibiting the initial deamination of AA to a highly reactive aldehyde.