Descending pathways mediating cardiovascular response from dorsomedial hypothalamic nucleus.
Physiological and anatomic methods were used to determine whether neurons in the rostral ventrolateral medulla (RVLM), nucleus tractus solitarius (NTS), or hypothalamic paraventricular nucleus (PVN) mediate the cardiovascular response evoked from the dorsomedial hypothalamic nucleus (DMH), which is believed to play a key role in mediating responses to stress. In urethane-anesthetized rats, activation of neurons in the DMH by microinjection of bicuculline resulted in a large increase in arterial pressure, heart rate, and renal sympathetic nerve activity. The pressor and sympathoexcitatory responses, but not the tachycardic response, were greatly reduced after bilateral muscimol injections into the RVLM even when baseline arterial pressure was maintained at a constant level. These responses were not reduced by muscimol injections into the PVN or NTS. Retrograde tracing experiments identified many neurons in the DMH that projected directly to the RVLM. The results indicate that the vasomotor and cardiac components of the response evoked from the DMH are mediated by pathways that are dependent and independent, respectively, of neurons in the RVLM.
Fontes
M A
MA
Department of Physiology and Institute for Biomedical Research, University of Sydney, New South Wales 2006, Australia. peliky@mono.icb.ufmg.br
Tagawa
T
T
Polson
J W
JW
Cavanagh
S J
SJ
Dampney
R A
RA
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000818:Animals; D001640:Bicuculline / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002319:Cardiovascular System / Q000294:innervation*; D004302:Dorsomedial Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018755:GABA Agonists / Q000008:administration & dosage; D018756:GABA Antagonists / Q000008:administration & dosage; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007275:Injections, Intravenous; D007668:Kidney / Q000294:innervation; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D008863:Microspheres; D009118:Muscimol / Q000008:administration & dosage; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology
D000319:Adrenergic beta-Antagonists; D018755:GABA Agonists; D018756:GABA Antagonists; D009118:Muscimol; D001640:Bicuculline