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Title: CDNA CLONING AND TISSUE-SPECIFIC GENE EXPRESSION OF OVINE LEPTIN, NPY-Y1 RECEPTOR AND NPY-Y2 RECEPTOR

Author
item DYER, C - UNIVERSITY OF MISSOURI
item SIMMONS, J - UNIVERSITY OF MISSOURI
item Matteri, Robert
item KEISLER, D - UNIVERSITY OF MISSOURI

Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Adequate food intake is required for animal growth and reproduction. Two hormones which play a role in appetite control are leptin and neuropeptide Y (NPY). Leptin and NPY are hormones which inhibit and stimulate appetite, respectively. Leptin decreases the production of NPY. In the first portion of this study, we produced the first DNA clones of sheep leptin and dtwo forms of the NPY receptor. A tissue can respond to NPY only if specific cell proteins (NPY receptors) are present. DNA produced from the clones was used to detect the presence of leptin and NPY receptors in tissues known to be involved in the control of appetite and reproduction. Leptin was found only in fat, which is a tissue affected by food intake. Receptors for NPY were found in brain areas which control appetite and reproduction. Receptors for NPY also were found in the pancreas (source of insulin) and the pituitary gland (source of several reproductive hormones). .The identification of the source of leptin and of tissues with the ability to respond to NPY represents an important first step in understanding the complex biological systems linking food intake, growth, and reproduction.

Technical Abstract: The physiological regulation of food intake is a critical factor in both the rate at which an animal grows and its reproductive activity. Recently, progress has been made in elucidating a complex system in which insulin, leptin and neuropeptide Y play integral roles to monitor an animal's energy balance and regulate feed intake and fertility. RNA was extracted from ovine hypothalamic, anterior pituitary, pancreas and adipose tissue. Usin the reverse transcription-polymerase chain reaction, cDNAs were cloned and sequenced for leptin (Genbank accession no. U62123 and U84247), NPY-Y1 receptor (Genbank accession no. U62122) and NPY-Y2 receptor (Genbank accession no. U83458). Probes generated from these clones were used to detect mRNA expression within tissues thought to be involved in the co- regulation of feed intake and reproduction. Leptin was found to be expressed in sheep adipose tissue. The ovine NPY-Y1 receptor mRNA was detected within the arcuate nucleus and paraventricular nucleus of the hypothalamus, the dentate gyrus of the hippocampus and in pancreatic, anterior pituitary, and adipose tissues. Expression of ovine NPY-Y2 receptor mRNA was detected in the hippocampus and within pancreatic tissue. These observations provide evidence of potential mechanisms which exist for mediating communication between peripheral and central tissues within the insulin-leptin-NPY pathway.