Glucoprivation in the ventrolateral medulla decreases brown adipose tissue sympathetic nerve activity by decreasing the activity of neurons in raphé pallidus

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Abstract

In urethane/α-chloralose anesthetized rats, cold exposure increased brown adipose tissue sympathetic nerve activity (BAT SNA: +699 ± 104% control). Intravenous administration of 2-deoxy-d-glucose (2-DG; 200 mg·ml -1·kg -1) reversed the cold-evoked activation of BAT SNA (nadir: 139 ± 36% of control) and decreased BAT temperature (-1.1 ± 0.2°C), expired CO 2 (-0.4 ± 0.1%), and core temperature (-0.5 ± 0.0). Similarly, unilateral nanoinjection of the glucoprivic agent 5-thioglucose (5-TG; 12 μg/100 nl) in the ventrolateral medulla (VLM) completely reversed the cold-evoked increase in BAT SNA (nadir: 104 ± 7% of control), and decreased T BAT (-1.4 ± 0.3°C), expired CO 2 (-0.2 ± 0.0%), and heart rate (-35 ± 10 beats/min). The percentage of rostral raphé pallidus (RPa)-projecting neurons in the dorsal hypothalamic area/dorsomedial hypothalamus that expressed Fos in response to cold exposure (ambient temperature: 4-10°C) did not differ between saline (28 ± 6%) and 2-DG (30 ± 5%) pretreated rats, whereas the percentage of spinally projecting neurons in the RPa/raphé magnus that expressed Fos in response to cold exposure was lower in 2-DG- compared with saline-pretreated rats (22 ± 6% vs. 42 ± 5%, respectively). The increases in BAT SNA evoked by nanoinjection of bicuculline in the RPa or by transection of the neuraxis at the pontomedullary border were resistant to inhibition by glucoprivation. These results suggest that neurons within the VLM play a role in the glucoprivic inhibition of BAT SNA and metabolism, that this inhibition requires neural structures rostral to the pontomedullary border, and that this inhibition is mediated by a GABAergic input to the RPa.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume302
Issue number2
DOIs
StatePublished - Jan 2012

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Brown Adipose Tissue
Neurons
Carbon Monoxide
Temperature
Neural Inhibition
Chloralose
Bicuculline
Urethane
Intravenous Administration
Hypothalamus
Heart Rate
Glucose

Keywords

  • 2-DG
  • CVLM
  • Hypoglycemia
  • Metabolism
  • RVLM
  • Thermoregulation

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

@article{ba7ce4142188444fba8d036fdabef322,
title = "Glucoprivation in the ventrolateral medulla decreases brown adipose tissue sympathetic nerve activity by decreasing the activity of neurons in raph{\'e} pallidus",
abstract = "In urethane/α-chloralose anesthetized rats, cold exposure increased brown adipose tissue sympathetic nerve activity (BAT SNA: +699 ± 104{\%} control). Intravenous administration of 2-deoxy-d-glucose (2-DG; 200 mg·ml -1·kg -1) reversed the cold-evoked activation of BAT SNA (nadir: 139 ± 36{\%} of control) and decreased BAT temperature (-1.1 ± 0.2°C), expired CO 2 (-0.4 ± 0.1{\%}), and core temperature (-0.5 ± 0.0). Similarly, unilateral nanoinjection of the glucoprivic agent 5-thioglucose (5-TG; 12 μg/100 nl) in the ventrolateral medulla (VLM) completely reversed the cold-evoked increase in BAT SNA (nadir: 104 ± 7{\%} of control), and decreased T BAT (-1.4 ± 0.3°C), expired CO 2 (-0.2 ± 0.0{\%}), and heart rate (-35 ± 10 beats/min). The percentage of rostral raph{\'e} pallidus (RPa)-projecting neurons in the dorsal hypothalamic area/dorsomedial hypothalamus that expressed Fos in response to cold exposure (ambient temperature: 4-10°C) did not differ between saline (28 ± 6{\%}) and 2-DG (30 ± 5{\%}) pretreated rats, whereas the percentage of spinally projecting neurons in the RPa/raph{\'e} magnus that expressed Fos in response to cold exposure was lower in 2-DG- compared with saline-pretreated rats (22 ± 6{\%} vs. 42 ± 5{\%}, respectively). The increases in BAT SNA evoked by nanoinjection of bicuculline in the RPa or by transection of the neuraxis at the pontomedullary border were resistant to inhibition by glucoprivation. These results suggest that neurons within the VLM play a role in the glucoprivic inhibition of BAT SNA and metabolism, that this inhibition requires neural structures rostral to the pontomedullary border, and that this inhibition is mediated by a GABAergic input to the RPa.",
keywords = "2-DG, CVLM, Hypoglycemia, Metabolism, RVLM, Thermoregulation",
author = "Madden, {Christopher (Chris)}",
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T1 - Glucoprivation in the ventrolateral medulla decreases brown adipose tissue sympathetic nerve activity by decreasing the activity of neurons in raphé pallidus

AU - Madden, Christopher (Chris)

PY - 2012/1

Y1 - 2012/1

N2 - In urethane/α-chloralose anesthetized rats, cold exposure increased brown adipose tissue sympathetic nerve activity (BAT SNA: +699 ± 104% control). Intravenous administration of 2-deoxy-d-glucose (2-DG; 200 mg·ml -1·kg -1) reversed the cold-evoked activation of BAT SNA (nadir: 139 ± 36% of control) and decreased BAT temperature (-1.1 ± 0.2°C), expired CO 2 (-0.4 ± 0.1%), and core temperature (-0.5 ± 0.0). Similarly, unilateral nanoinjection of the glucoprivic agent 5-thioglucose (5-TG; 12 μg/100 nl) in the ventrolateral medulla (VLM) completely reversed the cold-evoked increase in BAT SNA (nadir: 104 ± 7% of control), and decreased T BAT (-1.4 ± 0.3°C), expired CO 2 (-0.2 ± 0.0%), and heart rate (-35 ± 10 beats/min). The percentage of rostral raphé pallidus (RPa)-projecting neurons in the dorsal hypothalamic area/dorsomedial hypothalamus that expressed Fos in response to cold exposure (ambient temperature: 4-10°C) did not differ between saline (28 ± 6%) and 2-DG (30 ± 5%) pretreated rats, whereas the percentage of spinally projecting neurons in the RPa/raphé magnus that expressed Fos in response to cold exposure was lower in 2-DG- compared with saline-pretreated rats (22 ± 6% vs. 42 ± 5%, respectively). The increases in BAT SNA evoked by nanoinjection of bicuculline in the RPa or by transection of the neuraxis at the pontomedullary border were resistant to inhibition by glucoprivation. These results suggest that neurons within the VLM play a role in the glucoprivic inhibition of BAT SNA and metabolism, that this inhibition requires neural structures rostral to the pontomedullary border, and that this inhibition is mediated by a GABAergic input to the RPa.

AB - In urethane/α-chloralose anesthetized rats, cold exposure increased brown adipose tissue sympathetic nerve activity (BAT SNA: +699 ± 104% control). Intravenous administration of 2-deoxy-d-glucose (2-DG; 200 mg·ml -1·kg -1) reversed the cold-evoked activation of BAT SNA (nadir: 139 ± 36% of control) and decreased BAT temperature (-1.1 ± 0.2°C), expired CO 2 (-0.4 ± 0.1%), and core temperature (-0.5 ± 0.0). Similarly, unilateral nanoinjection of the glucoprivic agent 5-thioglucose (5-TG; 12 μg/100 nl) in the ventrolateral medulla (VLM) completely reversed the cold-evoked increase in BAT SNA (nadir: 104 ± 7% of control), and decreased T BAT (-1.4 ± 0.3°C), expired CO 2 (-0.2 ± 0.0%), and heart rate (-35 ± 10 beats/min). The percentage of rostral raphé pallidus (RPa)-projecting neurons in the dorsal hypothalamic area/dorsomedial hypothalamus that expressed Fos in response to cold exposure (ambient temperature: 4-10°C) did not differ between saline (28 ± 6%) and 2-DG (30 ± 5%) pretreated rats, whereas the percentage of spinally projecting neurons in the RPa/raphé magnus that expressed Fos in response to cold exposure was lower in 2-DG- compared with saline-pretreated rats (22 ± 6% vs. 42 ± 5%, respectively). The increases in BAT SNA evoked by nanoinjection of bicuculline in the RPa or by transection of the neuraxis at the pontomedullary border were resistant to inhibition by glucoprivation. These results suggest that neurons within the VLM play a role in the glucoprivic inhibition of BAT SNA and metabolism, that this inhibition requires neural structures rostral to the pontomedullary border, and that this inhibition is mediated by a GABAergic input to the RPa.

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KW - Hypoglycemia

KW - Metabolism

KW - RVLM

KW - Thermoregulation

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