Expression of corticotropin-releasing factor and its receptors in the brain of lean and obese Zucker rats

Expression of CRF messenger RNA (mRNA) and heteronuclear RNA (hnRNA) as well as the mRNAs encoding the CRF receptors of type 1 (CRF1R) and type 2 alpha (CFR2R) in the brain has been investigated in lean (Fa/?) and obese (fa/fa) Zucker rats. Exonic and intronic in situ hybridization histochemistry was employed to measure the mRNA and hnRNA levels in rats killed before (resting state), during, and 120 min after a treadmill running session. The resting expression of CRF hnRNA in the hypothalamic paraventricular nucleus (PVN) of obese rats was minimal and comparable to that of lean rats. However, during treadmill running, this expression was higher in obese than in lean rats. In obese rats, the transcription of the CRF1R mRNA in the PVN was high under resting conditions, dropped considerably during running, and rose again to elevated levels 120 min after the treadmill session. In lean rats, CRF1R mRNA in the PVN was minimal before and during running, but rose to a value similar to that in obese rats 120 min a...