Age- and genotype-dependent differences in catecholamine concentrations in the porcine caudate nucleus.

Catecholamine concentrations of the caudate nucleus were determined by radioenzymatic assay in stress-susceptible and stress-resistant pigs at five different ages. Dopamine concentrations increased with age up to the time of puberty and declined thereafter in both genotypes of pigs. Generally, epinephrine concentrations increased with increasing age in both genotypes of pigs. Norepinephrine concentrations remained relatively constant for all ages of pigs except the oldest pigs. For most age groups, dopamine concentrations were lower in pigs of stress-susceptible genotype than in stress-resistant genotype.