Figure 33. In situ hybridization autoradiographs of proTRH mRNA in the PVN (arrow) of (A) normal fed and (B) fasting animals. Note the marked reduction in hybridization signal by fasting. (C) ProTRH mRNA levels are restored to normal in fasting animals administered leptin. (From G. Legradi, C.H. Emerson, R.S. Ahima, J.S. Flier, R.M. Lechan, Leptin Prevents Fasting-Induced Suppression of Prothyrotropin-Releasing Hormone Messenger Ribonucleic Acid in Neurons of the Hypothalamic Paraventricular Nucleus, 1997, Endocrinology 138: 2569-2576.)