Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2000
Publication Date: N/A
Technical Abstract: Melanin-concentrating hormone (MCH) stimulates feeding when administered to rats and is highly expressed in ob/ob mice. The purpose of this study was to clone the coding region of the mature porcine MCH peptide, screen various tissues for the presence of MCH mRNA, and evaluate MCH gene expression in newly weaned vs unweaned pigs. RT-PCR was used to produce a 272 bp MCH DNA fragment from porcine hypothalamic RNA. The identity of the clone DNA was verified by dideoxy termination sequencing and found to be 94 percent homologous with the human MCH sequence. Pooled RNAs were prepared from hypothalamus, pituitary, fat, muscle, liver,spleen, thymus, adrenal and testis (3-4 piglets/tissue pool). RT-PCR revealed detectable MCH expression only in the hypothalamus. Fourteen-day-old nursing pigs were either kept with their sow or weaned onto starter diets containing 0 or 7 percent plasma protein (n=8/group). Piglets were further allocated by size einto small (3.5-4.3 kg) and large (4.6-5.7 kg) groups. Piglets were sacrificed 4 d later for tissue collection. Hypothalamic MCH mRNA levels (relative to 28S rRNA)did not differ among weaning groups (P=.7) but tended to be higher in the large piglets (P=.058). Hypothalamic MCH mRNA levels were positively correlated with serum insulin concentrations (P=.04) and levels of hypothalamic mRNAs for neuropeptide Y, orexin and agouti-related protein (P<.002), but not with leptin receptor mRNA (P=.15). Levels of MCH and adipose leptin mRNAs were inversely related (P=.05). The present results are consistent with a responsiveness of MCH to peripheral and central endocrine/neuroendocrine signals of nutritional status and appetite.