Differential postsynaptic compartments in the laterocapsular division of the central nucleus of amygdala for afferents from the parabrachial nucleus and the basolateral nucleus in the rat

• Published in: Journal of comparative neurology (1911) Vol. 518; no. 23; pp. 4771 - 4791
• Main Authors: Dong, Yu-Lin, Fukazawa, Yugo, Wang, Wen, Kamasawa, Naomi, Shigemoto, Ryuichi
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.12.2010; Wiley Subscription Services, Inc
• Subjects: Afferent Pathways - physiology; Afferent Pathways - ultrastructure; AMPA receptor; Amygdala - physiology; Amygdala - ultrastructure; Animals; dendritic shaft; Lentivirus; Male; Microscopy, Immunoelectron - methods; Neurons - physiology; Neurons - ultrastructure; nociceptive amygdala; postsynaptic density; Rats; Rats, Wistar; SDS-FRL; spine; Synapses - physiology; Synapses - ultrastructure
• ISSN: 0021-9967; 1096-9861; 1096-9861
• DOI: 10.1002/cne.22487

Neurons in the laterocapsular division of the central nucleus of the amygdala (CeC), which is known as the “nociceptive amygdala,” receive glutamatergic inputs from the parabrachial nucleus (PB) and the basolateral nucleus of amygdala (BLA), which convey nociceptive information from the dorsal horn of the spinal cord and polymodal information from the thalamus and cortex, respectively. Here, we examined the ultrastructural properties of PB– and BLA–CeC synapses identified with EGFP‐expressing lentivirus in rats. In addition, the density of synaptic AMPA receptors (AMPARs) on CeC neurons was studied by using highly sensitive SDS‐digested freeze‐fracture replica labeling (SDS‐FRL). Afferents from the PB made asymmetrical synapses mainly on dendritic shafts (88%), whereas those from the BLA were on dendritic spines (81%). PB–CeC synapses in dendritic shafts were significantly larger (median 0.072 μm2) than BLA–CeC synapses in spines (median 0.058 μm2; P = 0.02). The dendritic shafts that made synapses with PB fibers were also significantly larger than those that made synapses with BLA fibers, indicating that the PB fibers make synapses on more proximal parts of dendrites than the BLA fibers. SDS‐FRL revealed that almost all excitatory postsynaptic sites have AMPARs in the CeC. The density of AMPAR‐specific gold particles in individual synapses was significantly higher in spine synapses (median 510 particles/μm2) than in shaft synapses (median 427 particles/μm2; P = 0.01). These results suggest that distinct synaptic impacts from PB– and BLA–CeC pathways contribute to the integration of nociceptive and polymodal information in the CeC. J. Comp. Neurol. 518:4771–4791, 2010. © 2010 Wiley‐Liss, Inc.