Ke. Krout et Ad. Loewy, Parabrachial nucleus projections to midline and intralaminar thalamic nuclei of the rat, J COMP NEUR, 428(3), 2000, pp. 475-494
The projections from the parabrachial nucleus to the midline and intralamin
ar thalamic nuclei were examined in the rat. Stereotaxic injections of the
retrograde tracer cholera toxin-p (CTb) were made in each of the intralamin
ar nuclei of the dorsal thalamus (the lateral parafascicular, medial parafa
scicular, oval paracentral, central lateral, paracentral, and central media
l nuclei), as well as the midline thalamic nuclei (the paraventricular, int
ermediodorsal, mediodorsal, paratenial, rhomboid, reuniens, parvicellular p
art of the ventral posterior, and caudal ventral medial nuclei). The retrog
rade cell body labeling pattern within the parabrachial subnuclei was then
analyzed. The paracentral thalamic nucleus received an input only from the
internal lateral parabrachial subnucleus. However, this subnucleus also pro
jected to all the other intralaminar thalamic nuclei, except for the centra
l lateral thalamic nucleus, which received no parabrachial afferent inputs.
The external lateral parabrachial subnucleus projected to the lateral para
fascicular, reuniens, central medial, parvicellular part; of the ventral po
sterior, and caudal ventromedial thalamic nuclei. Following CTb injections
in the paraventricular thalamic nucleus, retrogradely labeled cells were fo
und in the central lateral, dorsal lateral, and external lateral parabrachi
al subnuclei. The medial and ventral lateral parabrachial. subnuclei projec
ted to the oval paracentral, parafascicular, and rhomboid thalamic nuclei.
Finally, the waist area of the parabrachial nucleus was densely labeled aft
er CTb injections in the parvicellular part of the ventral posterior thalam
ic nucleus. Nociceptive, visceral, and gustatory signals may reach specific
cortical and other forebrain sites via this parabrachial-thalamic pathway.
(C) 2000 Wiley-Liss, Inc.