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MCT Expression in the Ventromedial Hypothalamus is Not Increased by Recurrent Hypoglycemia
Author(s) -
Oberlin Douglas J,
Fecych Mariel,
Murray Coleman,
Morrison Ron,
Wideman Laurie,
Beverly Lee
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.989.2
Subject(s) - hypoglycemia , medicine , endocrinology , western blot , hypothalamus , chemistry , saline , insulin , biochemistry , gene
Recurrent hypoglycemia (RH) has been shown to lead to deficits in the counter‐regulatory response to subsequent hypoglycemia; however, the exact mechanisms of this effect are unknown. A proposed explanation has included increased lactate shuttling from astrocytes to neurons, which would blunt the change in glucose availability in the ventromedial hypothalamus (VMH). The objective of the current study was to measure changes in the lactate shuttling monocarboxylate transporter (MCT) proteins in the VMH after RH or control. Male Sprague‐Dawley rats (~250 g) received a subcutaneous injection of 0.9% saline or insulin (3–5 U/kg) on 3 consecutive days. Blood glucose was measured 30 minutes post‐injection via a pedal vein stick and glucometer. Animals were sacrificed 24 hr after the last episode of hypoglycemia, and the VMH was rapidly extracted, homogenized, and frozen at −80 c. MCT1, MCT2, MCT4, and GAPDH (as a loading control) were measured by western blot analysis. Quality One software was used to determine band density and the ratio of each MCT:GAPDH was calculated for each MCT in the VMH. MCT differences between groups were assessed using ANOVA (SAS 9.3). Results There was a significant decrease in average 30 minute post‐injection glucose in the RH group (f=402.237, p<0.001). The results showed no significant differences between the RH and control group for MCT proteins (λ=0.867, p=0.404; MCT1 F=2.87, p=0.104; MCT2 F=2.14, p=0.157; MCT4 F=0.07, p=0.796). In conclusion, these findings suggest that RH does not increase MCT expression in the VMH and that increased lactate shuttling is not likely to mediate the impaired counter‐regulatory response after recurrent hypoglycemia. Support or Funding Information Supported by NIH Grant DK082609