Reciprocal circuits involved in nitroglycerin-induced neuronal activation of autonomic regions and pain pathways: a double immunolabeling and tract-tracing study
C. Tassorelli et al., Reciprocal circuits involved in nitroglycerin-induced neuronal activation of autonomic regions and pain pathways: a double immunolabeling and tract-tracing study, BRAIN RES, 842(2), 1999, pp. 294-310
This study uses tract-tracing protocols to determine the circuitry of speci
fic nuclei involved in nitroglycerin-induced activation. Combined retrograd
e and anterograde tracers were injected into nuclei which consistently demo
nstrate robust Fos expression following our systemic nitroglycerin injectio
n paradigm. The nuclei, which conform to these criteria, that we have evalu
ated in this study ate the locus coeruleus, parabrachial nucleus and parave
ntricular nucleus of the hypothalamus. Dual Fos/tracer immunocytochemistry
in treated animals documented the existence of a subset of autonomic nuclei
which are activated by nitroglycerin injection and have reciprocal connect
ions. From the nature of this rich interconnection we suggest that nitrogly
cerin activates autonomic responses involved in cardiovascular presser mech
anisms. Nuclei which show strong Fos labeling following nitroglycerin admin
istration, but not traced in this study, include the nucleus trigeminalis c
audalis and the ventrolateral column of the periaqueductal gray, both of wh
ich mediate nociceptive modalities. These data confirm and expand on our pr
evious findings and demonstrate that nitroglycerin activates a complex set
of structures that: are functionally and structurally interconnected to art
iculate an integrated response. (C) 1999 Elsevier Science B.V. All rights r
eserved.