DISTRIBUTION OF CATECHOLAMINES IN THE CENTRAL-NERVOUS-SYSTEM OF THE PIG

The objective of this study was to document, through comprehensive mea ns, normal distribution and concentration of catecholamines in various regions of the CNS of pigs, an increasingly popular animal model used for transgenic manipulation of neural genes. The effects of gonadal s teroidal status on this distribution were also assessed by comparing C NS catecholamine concentrations among mature male pigs (boars), immatu re (gilts) and mature female pigs (sows), and adult male pigs castrate d prepuberally (barrows). Dissected tissue samples from the CNS were e xtracted in 2 N acetic acid, filtered through a 0.2 micron filter, the n quantitated by reverse-phase high performance liquid chromatography using a C-18 reverse phase column with electrochemical detection. In b oth boars and sows the highest concentrations of norepinephrine (NE) w ere found in the diencephalic areas and brain stem. Gilts exhibited el evated concentrations of NE in the olfactory bulbs (OB), hypothalamus, pons, and corpus trapezoideum-locus ceruleus (LC) compared to lower c oncentrations in corresponding areas of sows. Prepuberal castration of the male was associated with significantly lower NE concentrations in the striatum, periaqueductal area (PAG), pons, LC, and spinal cord. T he sow exhibited significantly lower NE concentrations in the mammilla ry area (Mam), PAG, pons, and spinal cord than those in corresponding areas of the boar. Dopamine concentrations appeared to be similar in a ll areas of the brain and spinal cord studied in the sow and boar. Res ults demonstrated that prepuberal castration of the male appears to si gnificantly alter the DA content of the Mam and dorsal spinal cord, in contrast to gilts who possess significantly higher concentrations of DA. It is concluded from our studies that in general, catecholamine co ncentrations in various regions of the brain and spinal cord of sexual ly mature pigs parallel distributions of neuropeptides, substance P, a nd methionine enkephalin, as previously reported. In addition, signifi cant association was found between gonadal activity and catecholamine concentrations in discrete areas of the pig brain.