Neural catecholamine deficiencies in the porcine stress syndrome.

A study was conducted to compare catecholamine concentrations in nervous tissues of stress-susceptible (SS) and stress-resistant (SR) pigs that were physically stressed. Ten pigs were included in each group on the basis of results of halothane screening tests, blood typing analysis, and examination for serum creatine kinase (CK) activities at 6 weeks of age. The nervous tissues analyzed included the substantia nigra (SN) and the caudate nucleus (CN) which were taken from pigs as soon as possible after death and frozen in liquid nitrogen. Tissues were radioenzymatically assayed for dopamine, norepinephrine, and epinephrine concentrations. The SS pigs exhibited significantly greater (P less than 0.001) CK activity concentrations than did those SR pigs before and after physical stress. Concentrations of dopamine, norepinephrine, and epinephrine in the CN of SS pigs were significantly lower (P less than 0.05) than those in the CN of SR pigs. Similarly, the SN of SS pigs had lower dopamine, norepinephrine, and epinephrine concentrations than did the SN of SR pigs. The catecholamine deficiencies observed in the porcine stress syndrome seem to have similarities with certain human extrapyramidal diseases.