Different musical frequencies increase the neuronal and serum expression of Ghrelin hormone, in the rat.

It has shown that exists a relationship between listening to music and food-intake (1). Ghrelin (Ghre) stimulates appetite by acting on the ventral hypothalamus, which control food- intake. Ghre is secreted from the stomach and circulates in the bloodstream under fasting conditions, sending a hunger signal from the periphery to the CNS (2). The aim of this study was to evaluate the effects, in the rat, of different musical frequencies (432 and 440Hz) on immunohistochemical (IHC) neuronal expression of hypothalamic Ghre-containing neurons, and in addition to different production of Ghre hormones serum by Western blot assay (Wb), related to weight of animals. Cells count was carried out to allow the evaluation of Ghre-containing neurons for field of view after IHC processing; significant increased expression were observes in music-treated compared to control (CTR) groups. Furthermore, the Grhe serum expression was higher in groups treated with music compared to controls; in fact the Wb analysis shows a significant rais of Ghre serum concentration in treated groups compared to CTR group. Finally, interesting was the evaluation of the increase in weight, highly significant, in rats subjected to treatment with music compared to CTR. These results strongly support that different musical frequencies influence neuronal and serum level concentration of ghrelin in correlation with food-intake.