Fig. 2.
Effect of inhibition of neurons in the DMN and PVN on ARCN responses. A and C: unilateral microinjections of NMDA (10 mM, 30 nl) into the ARCN elicited increases in integrated IBATSNA and TBAT (open bars). Twenty minutes later, ipsilateral DMN was identified by microinjections of NMDA, and after NMDA effects subsided, muscimol (1 mM, 50 nl) was microinjected into the DMN (arrow); inhibition of DMN neurons did not elicit significant changes in IBATSNA and TBAT (not shown). Within 2–3 min, NMDA was again microinjected into the ARCN; increases in IBATSNA and TBAT were significantly attenuated after inhibition of DMN neurons (black bars). B and D: in the same animals, microinjections of artificial cerebrospinal fluid (aCSF) (50 nl) into the DMN did not alter significantly NMDA-induced responses in IBATSNA and TBAT. E and G: procedures used were identical to those mentioned in A and C, except that muscimol was microinjected into the PVN previously identified by microinjections of NMDA. F and H: procedures used were identical to those mentioned in B and D, except that aCSF was microinjected into the PVN. Microinjections of muscimol, but not aCSF, into the PVN significantly attenuated increases in IBATSNA and TBAT elicited by ARCN stimulation. *P < 0.05; **P < 0.01.