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Conditional viral tracing reveals that steroidogenic factor 1‐positive neurons of the dorsomedial subdivision of the ventromedial hypothalamus project to autonomic centers of the hypothalamus and hindbrain
Author(s) -
Lindberg Daniel,
Chen Peilin,
Li Chien
Publication year - 2013
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23338
Subject(s) - biology , hypothalamus , brainstem , neuroscience , nucleus , anterograde tracing , rostral ventrolateral medulla , hindbrain , anatomy , medicine , central nervous system , medulla oblongata
Excitation of neurons in the ventromedial hypothalamus (VMH), especially those residing in the dorsomedial part of the nucleus (VMHdm), evokes sympathetic nervous system (SNS) outflow, modulating a number of physiological functions including feeding and blood glucose homeostasis. However, the anatomical basis of VMH‐mediated SNS activation has thus far proved elusive. To understand how VMH neurons exercise output functions and describe an anatomical link between these neurons and the SNS, we identified downstream neural targets of the VMHdm by injecting an adenoviral vector encoding Cre recombinase (Cre)‐regulated farnesylated green fluorescent protein (GFP f ) into the VMHdm of mice that express Cre in neurons expressing the VMH‐specific transcription factor steroidogenic factor 1 (SF1). We confirm previously described projection patterns of the VMHdm and report the existence of a formerly unidentified projection pathway to a number of autonomic centers in the brainstem. These VMH efferents travel caudally through the periaqueductal gray (PAG) and then ventrally through the lateral lemniscus to the ventral surface of the brain, where they eventually reach caudal autonomic centers including the C1 catecholamine cell group of the rostral ventrolateral medulla (RVLM) and the nucleus of the solitary tract (NTS), where VMH efferents make close contacts with catecholaminergic neurons. We also found that VMHdm fibers reach a number of brainstem areas, including the retrotrapezoid nucleus (RTN), which are important in regulating respiration. Thus, the present study indicates that the VMH may modulate sympathetic and autonomic activity via synaptic contacts in the RTN, NTS, and RVLM and provides significant anatomical evidence to support a role of the VMH in respiratory regulation. J. Comp. Neurol. 521:3167–3190, 2013. © 2013 Wiley Periodicals, Inc.