The amygdala directly innervates adrenergic (C1) neurons in the ventrolateral medulla in the rat.
The innervation of adrenergic (C1) neurons in the ventrolateral medulla by the central amygdaloid nucleus (Ce) was investigated using immunohistochemical detection of phenylethanolamine N-methyltransferase (PNMT) combined with anterograde tracing through Phaseolus vulgaris leucoagglutinin (PHA-L) transport and lesion-induced axonal degeneration. Injections of PHA-L into the medial Ce labelled axons in close proximity to PNMT-immunoreactive dendrites and somata in the ventrolateral medulla. The PNMT-immunoreactive neurons within the rostral part of the nucleus reticularis rostroventrolateralis were preferentially innervated by the amygdaloid terminals. Degenerating terminals formed synaptic contacts on PNMT-immunoreactive cells of the ventrolateral medulla in animals with lesions of the Ce. The synaptic contacts were mainly found on dendrites and were usually of the symmetrical type. The present findings provide evidence that cells within the amygdala directly innervate presumed adrenergic cells in the ventrolateral medulla. This pathway may be part of the anatomical substrates that are activated during amygdaloid-mediated sympathetic activity.
Cassell
M D
MD
Department of Anatomy, University of Iowa, Iowa City 52242.
Gray
T S
TS
D000320:Adrenergic Fibers / Q000166:cytology* / Q000201:enzymology; D000679:Amygdala / Q000033:anatomy & histology* / Q000166:cytology; D000818:Animals; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000033:anatomy & histology* / Q000166:cytology / Q000201:enzymology; D009410:Nerve Degeneration; D009434:Neural Pathways / Q000033:anatomy & histology; D010625:Phenylethanolamine N-Methyltransferase / Q000378:metabolism; D010835:Phytohemagglutinins; D051381:Rats
D010835:Phytohemagglutinins; D010625:Phenylethanolamine N-Methyltransferase