Initial experience with seven tesla magnetic resonance spectroscopy of hypothalamic GABA during hyperinsulinemic euglycemia and hypoglycemia in healthy humans

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Abstract

Purpose Hypothalamic GABA signaling has been shown to regulate the hormonal response to hypoglycemia in animals. The hypothalamus is a challenging brain region for magnetic resonance spectroscopy (MRS) due to its small size and central location. To investigate the feasibility of measuring GABA in the hypothalamus in humans, ultra-high field MRS was used. Methods GABA levels in the hypothalamus and occipital cortex (control region) were measured in healthy volunteers during euglycemia and hypoglycemia at 7 tesla using short-echo STEAM (TE = 8 ms, TR = 5 s). Results Hypothalamic GABA levels were quantified with a mean within-session test-retest coefficient of variance of 9%. Relatively high GABA levels were observed in the hypothalamus compared with other brain regions. Hypothalamic GABA levels were 3.5 ± 0.3 μmol/g during euglycemia (glucose 89 ± 6 mg/dL) vs. 3.0 ± 0.4 μmol/g during hypoglycemia (glucose 61 ± 3 mg/dL) (P = 0.06, N = 7). In the occipital cortex, GABA levels remained constant at 1.4 ± 0.4 vs.1.4 ± 0.3 μmol/g (P = 0.3, N = 5) as glucose fell from 91 ± 4 to 61 ± 4 mg/dL. Conclusion GABA concentration can be quantified in the human hypothalamus and shows a trend toward decrease in response to an acute fall in blood glucose. These methods can be used to further investigate role of GABA signaling in the counterregulatory response to hypoglycemia in humans.

Original languageEnglish (US)
Pages (from-to)12-18
Number of pages7
JournalMagnetic resonance in medicine
Volume71
Issue number1
DOIs
StatePublished - Jan 1 2014

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Hypoglycemia
gamma-Aminobutyric Acid
Magnetic Resonance Spectroscopy
Hypothalamus
Occipital Lobe
Glucose
Brain
Blood Glucose
Healthy Volunteers

Keywords

  • 7 tesla
  • GABA
  • hypoglycemia
  • hypothalamus
  • magnetic resonance spectroscopy

Cite this

@article{206892b21d6140b49861a195aac7c6a0,
title = "Initial experience with seven tesla magnetic resonance spectroscopy of hypothalamic GABA during hyperinsulinemic euglycemia and hypoglycemia in healthy humans",
abstract = "Purpose Hypothalamic GABA signaling has been shown to regulate the hormonal response to hypoglycemia in animals. The hypothalamus is a challenging brain region for magnetic resonance spectroscopy (MRS) due to its small size and central location. To investigate the feasibility of measuring GABA in the hypothalamus in humans, ultra-high field MRS was used. Methods GABA levels in the hypothalamus and occipital cortex (control region) were measured in healthy volunteers during euglycemia and hypoglycemia at 7 tesla using short-echo STEAM (TE = 8 ms, TR = 5 s). Results Hypothalamic GABA levels were quantified with a mean within-session test-retest coefficient of variance of 9{\%}. Relatively high GABA levels were observed in the hypothalamus compared with other brain regions. Hypothalamic GABA levels were 3.5 ± 0.3 μmol/g during euglycemia (glucose 89 ± 6 mg/dL) vs. 3.0 ± 0.4 μmol/g during hypoglycemia (glucose 61 ± 3 mg/dL) (P = 0.06, N = 7). In the occipital cortex, GABA levels remained constant at 1.4 ± 0.4 vs.1.4 ± 0.3 μmol/g (P = 0.3, N = 5) as glucose fell from 91 ± 4 to 61 ± 4 mg/dL. Conclusion GABA concentration can be quantified in the human hypothalamus and shows a trend toward decrease in response to an acute fall in blood glucose. These methods can be used to further investigate role of GABA signaling in the counterregulatory response to hypoglycemia in humans.",
keywords = "7 tesla, GABA, hypoglycemia, hypothalamus, magnetic resonance spectroscopy",
author = "Amir Moheet and Emir, {U. E.} and Melissa Terpstra and A. Kumar and Eberly, {Lynn E} and Seaquist, {Elizabeth R} and Gulin Oz",
year = "2014",
month = "1",
day = "1",
doi = "10.1002/mrm.24663",
language = "English (US)",
volume = "71",
pages = "12--18",
journal = "Magnetic Resonance in Medicine",
issn = "0740-3194",
publisher = "John Wiley and Sons Inc.",
number = "1",

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TY - JOUR

T1 - Initial experience with seven tesla magnetic resonance spectroscopy of hypothalamic GABA during hyperinsulinemic euglycemia and hypoglycemia in healthy humans

AU - Moheet, Amir

AU - Emir, U. E.

AU - Terpstra, Melissa

AU - Kumar, A.

AU - Eberly, Lynn E

AU - Seaquist, Elizabeth R

AU - Oz, Gulin

PY - 2014/1/1

Y1 - 2014/1/1

N2 - Purpose Hypothalamic GABA signaling has been shown to regulate the hormonal response to hypoglycemia in animals. The hypothalamus is a challenging brain region for magnetic resonance spectroscopy (MRS) due to its small size and central location. To investigate the feasibility of measuring GABA in the hypothalamus in humans, ultra-high field MRS was used. Methods GABA levels in the hypothalamus and occipital cortex (control region) were measured in healthy volunteers during euglycemia and hypoglycemia at 7 tesla using short-echo STEAM (TE = 8 ms, TR = 5 s). Results Hypothalamic GABA levels were quantified with a mean within-session test-retest coefficient of variance of 9%. Relatively high GABA levels were observed in the hypothalamus compared with other brain regions. Hypothalamic GABA levels were 3.5 ± 0.3 μmol/g during euglycemia (glucose 89 ± 6 mg/dL) vs. 3.0 ± 0.4 μmol/g during hypoglycemia (glucose 61 ± 3 mg/dL) (P = 0.06, N = 7). In the occipital cortex, GABA levels remained constant at 1.4 ± 0.4 vs.1.4 ± 0.3 μmol/g (P = 0.3, N = 5) as glucose fell from 91 ± 4 to 61 ± 4 mg/dL. Conclusion GABA concentration can be quantified in the human hypothalamus and shows a trend toward decrease in response to an acute fall in blood glucose. These methods can be used to further investigate role of GABA signaling in the counterregulatory response to hypoglycemia in humans.

AB - Purpose Hypothalamic GABA signaling has been shown to regulate the hormonal response to hypoglycemia in animals. The hypothalamus is a challenging brain region for magnetic resonance spectroscopy (MRS) due to its small size and central location. To investigate the feasibility of measuring GABA in the hypothalamus in humans, ultra-high field MRS was used. Methods GABA levels in the hypothalamus and occipital cortex (control region) were measured in healthy volunteers during euglycemia and hypoglycemia at 7 tesla using short-echo STEAM (TE = 8 ms, TR = 5 s). Results Hypothalamic GABA levels were quantified with a mean within-session test-retest coefficient of variance of 9%. Relatively high GABA levels were observed in the hypothalamus compared with other brain regions. Hypothalamic GABA levels were 3.5 ± 0.3 μmol/g during euglycemia (glucose 89 ± 6 mg/dL) vs. 3.0 ± 0.4 μmol/g during hypoglycemia (glucose 61 ± 3 mg/dL) (P = 0.06, N = 7). In the occipital cortex, GABA levels remained constant at 1.4 ± 0.4 vs.1.4 ± 0.3 μmol/g (P = 0.3, N = 5) as glucose fell from 91 ± 4 to 61 ± 4 mg/dL. Conclusion GABA concentration can be quantified in the human hypothalamus and shows a trend toward decrease in response to an acute fall in blood glucose. These methods can be used to further investigate role of GABA signaling in the counterregulatory response to hypoglycemia in humans.

KW - 7 tesla

KW - GABA

KW - hypoglycemia

KW - hypothalamus

KW - magnetic resonance spectroscopy

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U2 - 10.1002/mrm.24663

DO - 10.1002/mrm.24663

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SP - 12

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JF - Magnetic Resonance in Medicine

SN - 0740-3194

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