Neuroscience 2005 Abstract
| Presentation Number: | 580.8 |
|---|---|
| Abstract Title: | Imaging ghrelin action <i>in vivo</i> using manganese-enhanced MRI (MEMRI). |
| Authors: |
Parkinson, J. R. C.*1
; Kuo, Y.2
; Herlihy, A. H.2
; So, P.2
; Small, C. J.1
; Bell, J. D.2
; Bloom, S. R.1
1Metabolic Medicine, Imperial Col., London, United Kingdom 2Molecular Imaging Group, Imperial Col., London, United Kingdom |
| Primary Theme and Topics |
Homeostatic and Neuroendocrine Systems - Regulation of Food Intake and Body Weight -- Integration of peripheral signals |
| Secondary Theme and Topics | Techniques in Neuroscience<br />- Mass Spec and Other Biochemical and Analytical Methods |
| Session: |
580. Food Intake and Body Weight: Integrative Studies Slide |
| Presentation Time: | Tuesday, November 15, 2005 9:45 AM-10:00 AM |
| Location: | Washington Convention Center - Room 140A |
| Keywords: | appetite, neuroimaging, arcuate, neuropeptide |
Manganese-enhanced MRI (MEMRI) is a neuroimaging technique with the potential to differentiate neuronal connectivity and assess temporal responses to stimuli controlling food intake in vivo. It offers many advantages over c-fos expression analysis, generating a real time representation of hypothalamic neuronal activity. Here we employ MEMRI analysis in conjunction with a murine model of appetite stimulation using the orexigenic gut hormone, ghrelin.
T1 weighted scans were performed on male C57BL/6 mice in a 9.4T horizontal-bore MR scanner, before and after intravenous (IV) infusion of 100mM MnCl2 and intraperitoneal (IP) administration of ghrelin (0.06 and 0.3 nmol/g body weight) or saline (n = 4-5 /group). The signal intensities (SI) of various hypothalamic nuclei, incuding the arcuate nucleus (ARC), periventricular nucleus (PE) and paraventricular nucleus (PVN), aswell as the ventromedial hypothalamus (VMH), anterior pituitary gland (AP) and 4th ventricle were measured by drawing regions of interest (ROI) with imaging processing software (Image J 1.3.1, NIH, US).
Post IV MnCl2, the SI of structures inside the blood brain barrier gradually increased, reaching a peak at around 40-50 min and then a plateau 70 min post infusion. The time course curves show a region specific response to IP ghrelin. In the ARC and PE significantly higher SI were observed after MnCl2 infusion in response to IP ghrelin compared to control. The ARC SI is increased after only 15 minutes post IP injection, which suggests a rapid hypothalamic response to the ghrelin. A dose dependent increase in SI in response to ghrelin administration was seen in the VMH (P<0.001). Thus, MnCl2 enhancement can be used to trace the region-specific effects of the gut peptide ghrelin on neuronal activation, similar to those reported by c-fos in vitro. The ability to measure the effect of peptide administration in real time should aid the dissection and understanding of appetite regulating pathways.
T1 weighted scans were performed on male C57BL/6 mice in a 9.4T horizontal-bore MR scanner, before and after intravenous (IV) infusion of 100mM MnCl2 and intraperitoneal (IP) administration of ghrelin (0.06 and 0.3 nmol/g body weight) or saline (n = 4-5 /group). The signal intensities (SI) of various hypothalamic nuclei, incuding the arcuate nucleus (ARC), periventricular nucleus (PE) and paraventricular nucleus (PVN), aswell as the ventromedial hypothalamus (VMH), anterior pituitary gland (AP) and 4th ventricle were measured by drawing regions of interest (ROI) with imaging processing software (Image J 1.3.1, NIH, US).
Post IV MnCl2, the SI of structures inside the blood brain barrier gradually increased, reaching a peak at around 40-50 min and then a plateau 70 min post infusion. The time course curves show a region specific response to IP ghrelin. In the ARC and PE significantly higher SI were observed after MnCl2 infusion in response to IP ghrelin compared to control. The ARC SI is increased after only 15 minutes post IP injection, which suggests a rapid hypothalamic response to the ghrelin. A dose dependent increase in SI in response to ghrelin administration was seen in the VMH (P<0.001). Thus, MnCl2 enhancement can be used to trace the region-specific effects of the gut peptide ghrelin on neuronal activation, similar to those reported by c-fos in vitro. The ability to measure the effect of peptide administration in real time should aid the dissection and understanding of appetite regulating pathways.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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