Abstract
The central amygdaloid nucleus (CeA) receives projection from the The parabrachial nucleus (PBN) gustatory neurons and descendingly projects to the PBN. We have carried out neurophysiological and neuropharmacological experiments to assess whether the CeA is involved in modulating the gustatory activities of the PBN and the underlying mechanisms. The results showed that during CeA stimulation, the spontaneous activities of the taste neurons of PBN were depressed significantly(p<0.05) ,and the responses of the neurons to at least one effective taste stimulus of the four basic tastants were inhibited in most PBN neurons; Bilateral lesions of CeA facilitated the spontaneous discharges and the responses of PBN neurons to HCl and QHCl (P<0.01);Microinjection of 6-cyano-7-nitro-quinoxaline-2, 3-dione (CNQX), an AMPA receptor antagonist, into the CeA produced a time-dependent inhibition of the responses in 30% PBN taste neurons, with the responses to HCl and QHCl significantly lowered (P<0.05); After microinjection of bicuculline, a GABAA-selective antagonist, into the ipsilateral CeA , the responses of PBN neurons to four tastants all remarkably increased (P<0.01), respectively. However, after bicuculine was delivered into the contralateral CeA, the responses to NaCl, HCl and QHCl increased. These results not only support the involvement of the CeA in modulating gustatory activities of the PBN, but also provide clear evidences that the AMPA receptor and the GABAA receptor within the CeA are closely related to this modulation. [J Physiol Sci. 2008;58 Suppl:S50]
