Chemical stimulation of the dorsomedial hypothalamus evokes non-shivering thermogenesis in anesthetized rats

The hallmark neuroendocrine response to stress is increased plasma ACTH. Inhibition of neurons in the region of the dorsomedial hypothalamus (DMH) attenuates experimental air stress-induced elevation of heart rate (HR), mean arterial pressure (MAP), and plasma ACTH. We hypothesized that, under basal conditions, stimulation of the DMH would mimic the neuroendocrine and cardiovascular response to air stress. We examined the effects of unilateral microinjection (100-nl vol) of bicuculline methiodide (BMI, 10 pmol), kainate (KA, 1 or 3 pmol), and N-methyl-d-aspartate (5 pmol) into the DMH or the paraventicular nucleus (PVN) on HR, MAP, locomotor activity, and plasma ACTH in conscious rats. Chemical stimulation of the DMH with KA or BMI produced increased locomotor activity and effects on HR, MAP, and plasma ACTH that together mimicked the pattern seen in experimental stress. Similar treatment in the PVN produced only small increases in MAP. Thus activation of neurons in the region of the DMH results in increased secretion of ACTH along with other changes typically seen in experimental stress.

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Coactivation of renal sympathetic neurons and somatic motor neurons by chemical stimulation of the midbrain ventral tegmental area

Journal of Applied Physiology ◽

10.1152/japplphysiol.01233.2010 ◽

2011 ◽

Vol 110 (5) ◽

pp. 1342-1353 ◽

Cited By ~ 19

Author(s):

Tomoko Nakamoto ◽

Kanji Matsukawa ◽

Nan Liang ◽

Rie Wakasugi ◽

L. Britt Wilson ◽

...

Keyword(s):

Ventral Tegmental Area ◽

Sympathetic Nerve ◽

Cardiovascular Responses ◽

Chemical Stimulation ◽

Homocysteic Acid ◽

Renal Sympathetic Nerve ◽

Anesthetized Rats ◽

Ventral Tegmental ◽

Renal Sympathetic ◽

Stimulation Of

We examined whether neurons in the midbrain ventral tegmental area (VTA) play a role in generating central command responsible for autonomic control of the cardiovascular system in anesthetized rats and unanesthetized, decerebrated rats with muscle paralysis. Small volumes (60 nl) of an N-methyl-d-aspartate receptor agonist (l-homocysteic acid) and a GABAergic receptor antagonist (bicuculline) were injected into the VTA and substantia nigra (SN). In anesthetized rats, l-homocysteic acid into the VTA induced short-lasting increases in renal sympathetic nerve activity (RSNA; 66 ± 21%), mean arterial pressure (MAP; 5 ± 2 mmHg), and heart rate (HR; 7 ± 2 beats/min), whereas bicuculline into the VTA produced long-lasting increases in RSNA (130 ± 45%), MAP (26 ± 2 mmHg), and HR (66 ± 6 beats/min). Bicuculline into the VTA increased blood flow and vascular conductance of the hindlimb triceps surae muscle, suggesting skeletal muscle vasodilatation. However, neither drug injected into the SN affected all variables. Renal sympathetic nerve and cardiovascular responses to chemical stimulation of the VTA were not essentially affected by decerebration at the premammillary-precollicular level, indicating that the ascending projection to the forebrain from the VTA was not responsible for evoking the sympathetic and cardiovascular responses. Furthermore, bicuculline into the VTA in decerebrate rats produced long-lasting rhythmic bursts of RSNA and tibial motor nerve discharge, which occurred in good synchrony. It is likely that the activation of neurons in the VTA is capable of eliciting synchronized stimulation of the renal sympathetic and tibial motor nerves without any muscular feedback signal.

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Chemical stimulation of the ventrolateral medullary depressor area decreases ipsilateral cerebral blood flow in anesthetized rats

Brain Research ◽

10.1016/0006-8993(91)91048-6 ◽

1991 ◽

Vol 543 (1) ◽

pp. 61-68 ◽

Cited By ~ 23

Author(s):

Masanobu Maeda ◽

Abbott J. Krieger ◽

Hreday N. Sapru

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Chemical Stimulation ◽

Anesthetized Rats ◽

Stimulation Of

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Chemical stimulation of the nucleus tractus solitarii decreases spinal cord blood flow in anesthetized rats

Neuroscience Letters ◽

10.1016/0304-3940(94)11237-d ◽

1995 ◽

Vol 185 (2) ◽

pp. 111-114 ◽

Cited By ~ 6

Author(s):

Masanobu Maeda ◽

Masaiwa Inoueaa ◽

Seiji Takao ◽

Yoh Ikegami ◽

Masatsugu Nakai ◽

...

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Chemical Stimulation ◽

Nucleus Tractus Solitarii ◽

Spinal Cord Blood Flow ◽

Anesthetized Rats ◽

Stimulation Of

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Spinal cord blood flow decreases following chemical stimulation of the rostral ventrolateral medullary pressor area in anesthetized rats

Journal of the Autonomic Nervous System ◽

10.1016/0165-1838(92)90055-l ◽

1992 ◽

Vol 39 (2) ◽

pp. 151-157 ◽

Cited By ~ 11

Author(s):

Masanobu Maeda ◽

Abbott J. Krieger ◽

Masatsugu Nakai ◽

Hreday N. Sapru

Keyword(s):

Spinal Cord ◽

Blood Flow ◽

Cord Blood ◽

Chemical Stimulation ◽

Spinal Cord Blood Flow ◽

Anesthetized Rats ◽

Stimulation Of

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Ventromedial hypothalamic stimulation enhances peripheral glucose uptake in anesthetized rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1991.261.3.e298 ◽

1991 ◽

Vol 261 (3) ◽

pp. E298-E303 ◽

Cited By ~ 10

Author(s):

M. Sudo ◽

Y. Minokoshi ◽

T. Shimazu

Keyword(s):

Adipose Tissue ◽

Electrical Stimulation ◽

Glucose Uptake ◽

Rate Constant ◽

Skeletal Muscles ◽

Plasma Insulin ◽

Chemical Stimulation ◽

Peripheral Tissues ◽

Anesthetized Rats ◽

Stimulation Of

Effects of electrical and chemical stimulation of the ventromedial (VMH) and lateral hypothalamic (LH) nuclei on glucose uptake in peripheral tissues were studied by the 2-deoxy-D-[3H]glucose (2-[3H]DG) method in anesthetized rats. Electrical stimulation of the VMH increased the rate constant of glucose uptake in brown adipose tissue (BAT; 8 times), heart (3 times), and skeletal muscles (1.5 times) but not in white adipose tissue, diaphragm, and brain, without detectable changes in plasma insulin levels. Chemical stimulation of the VMH by microinjection of L-glutamate also enhanced the rate constant of glucose uptake in BAT, heart, and skeletal muscles preferentially, which indicates that the enhancement of glucose uptake in these tissues is derived from activation of VMH neurons. The increased rate of glucose uptake in BAT in response to VMH stimulation was effectively suppressed by surgical sympathetic denervation, suggesting a mediation of the sympathetic nerve in this effect. On the other hand, electrical stimulation of the LH had no appreciable effect on 2-[3H]DG uptake in any tissues. It is concluded that glucose uptake in certain peripheral tissues is accelerated selectively by activation of VMH neurons, the action of which is independent of plasma insulin but which is probably via the sympathetic nervous system.

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