Ghrelin, a hormone that affects growth and hunger, was given to rats to see how it changes other hormones in the brain. The researchers found that ghrelin increased levels of agouti-related peptide and neuropeptide Y, which are involved in regulating weight and hunger. However, it did not affect other hormones studied. In rats with growth hormone deficiency, ghrelin increased somatostatin levels in the brain. This study helps us understand how ghrelin affects food intake and growth hormone release in the body.