Hypothalamic stearoyl-CoA desaturase-2 (SCD2) controls whole-body energy expenditure
Authors: G F P de Souza
L F Nascimento
C Solon
J Morari
R F de Moura
W T Festuccia
L A Velloso
L M Ignacio-Souza
D S Razolli
Journal: International Journal of Obesity (2016)
Discipline: CLINICAL MEDICINE
Keywords: Stearoyl-CoA desaturase-2; hypothalamus; body mass gain; energy expenditure; central nervous system
Affiliations: Laboratory of Cell Signaling, Faculty of Medical Sciences, University of Campinas, Campinas, Brazil., Department of Physiology and Biophysics, University of Sao Paulo, Sao Paulo, Brazil.

Abstract:  Background/objectives: Stearoyl-CoA desaturase-2 (SCD2) is the main Œ¥9 desaturase expressed in the central nervous system. Because of its potential involvement in controlling whole-body adiposity, we evaluated the expression and function of SCD2 in the hypothalami of mice. Subjects/methods: Male mice of different strains were used in real-time PCR, immunoblot and metabolic experiments. In addition, antisense oligonucleotides and lentiviral vectors were used to reduce and increase the expression of SCD2 in the hypothalamus. Results: The level of SCD2 in the hypothalamus is similar to other regions of the central nervous system and is ~10-fold higher than in any other region of the body. In the arcuate nucleus, SCD2 is expressed in proopiomelanocortin and neuropeptide-Y neurons. Upon high fat feeding, the level of hypothalamic SCD2 increases. Inhibition of hypothalamic SCD2 as accomplished by two distinct approaches, an antisense oligonucleotide or a short-hairpin RNA delivered by a lentivirus, resulted in reduced body mass gain mostly due to increased energy expenditure and increased spontaneous activity. Increasing hypothalamic SCD2 by a lentivirus approach resulted in no change in body mass and food intake. Conclusions: Thus, SCD2 is highly expressed in the hypothalami of rodents and its knockdown reduces body mass due to increased whole-body energy expenditure. 

Retracted: No

PubPeer comments:
 the manuscript states:  Only few thyrotropin releasing hormone neurons of the paraventricular nucleus expressed SCD2 (Figure 2d), whereas no SCD2 immunoreactivity was detected in MCH neurons of the lateral hypothalamus (Figure 2e). However, no trh or mch staining can be seen in figure 2. The immunohistochemistry clearly did not work.  , 
 please note that the MCH antibody is not identified (no vendor....). , 
 The digital image in question supposedly represents immunostained MCH-positive cells in a fixed brain slice. However, even after adjusting the brightness of my monitor screen and enhancing the contrast of the image with the Photoshop software, I was still unable to discern any staining, biological objects, or pixel details. Without a doubt, this is an u201cemptyu201d image. Importantly, we are not talking about an image of a negative control experiment that is expected to be unlabeled (for example, staining from a knockout tissue). MCH is normally produced at very high levels in the hypothalamus. This implies either that the immunostaining completely failed, or that the image was dramatically under-exposed, or that the experiment was never performed. Several other images in the article are very dim and, to make the matter worse, the vendor of the anti-MCH antibody is not even listed. I cannot understand how the aforementioned u201cemptyu201d image was published without co-authors, reviewers, and editors asking questions about it. Furthermore, I must insist that an u201cemptyu201d image obtained with an unidentified antibody has no scientific value whatsoever. Is a western blot without bands or a graph without data acceptable science? Of course not! An empty image obtained with a mysterious antibody is not acceptable science either. , 
 #3 same issue with figure 5b , 
 Another issue is that the mouse arcuate nucleus is very small. thus, the administration of 1 microl of vector is not going to remain confined to this region, but will likely spread to most of the hypothalamus (if not extra-hypothalamic areas). , 
 Another detail: the brain slice in Figure 5a is at the level of the suprachiasmatic nucleus, not the arcuate nucleus. , 
 #3 I enhanced the brightness of the image posted in #1, setting Minimum Brightness to 45 in ImageJ. ***  ,