Fig. 1.  Administration of orexin-saporin (Ore-Sap) at tuberomamillary nucleus (TMN) induced loss of adenosine deaminase (ADA) immunoreactive neurons. Representative coronal section through the TMN from sham- (A ) and orexin-saporin–lesion (B ) rats. ADA-immunoreactive neurons in the TMN were significantly decreased (by 72%) in orexin-saporin–lesion rats compared with sham-lesion rats (n = 15 for sham lesion and n = 21 for orexin-saporin lesion, respectively; *P < 0.0001, compared with sham) (C ). 3v = third ventricle.