Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Aug;64:75-83.
doi: 10.1016/j.npep.2016.12.005. Epub 2016 Dec 20.

Embryonic Ablation of Neuronal VGF Increases Energy Expenditure and Reduces Body Weight

Affiliations
Free PMC article

Embryonic Ablation of Neuronal VGF Increases Energy Expenditure and Reduces Body Weight

Cheng Jiang et al. Neuropeptides. .
Free PMC article

Abstract

Germline ablation of VGF, a secreted neuronal, neuroendocrine, and endocrine peptide precursor, results in lean, hypermetabolic, and infertile adult mice that are resistant to diet-, lesion-, and genetically-induced obesity and diabetes (Hahm et al., 1999, 2002). To assess whether this phenotype is predominantly driven by reduced VGF expression in developing and/or adult neurons, or in peripheral endocrine and neuroendocrine tissues, we generated and analyzed conditional VGF knockout mice, obtained by mating loxP-flanked (floxed) Vgf mice with either pan-neuronal Synapsin-Cre- or forebrain alpha-CaMKII-Cre-recombinase-expressing transgenic mice. Adult male and female mice, with conditional ablation of the Vgf gene in embryonic neurons had significantly reduced body weight, increased energy expenditure, and were resistant to diet-induced obesity. Conditional forebrain postnatal ablation of VGF in male mice, primarily in adult excitatory neurons, had no measurable effect on body weight nor on energy expenditure, but led to a modest increase in adiposity, partially overlapping the effect of AAV-Cre-mediated targeted ablation of VGF in the adult ventromedial hypothalamus and arcuate nucleus of floxed Vgf mice (Foglesong et al., 2016), and also consistent with results of icv delivery of the VGF-derived peptide TLQP-21 to adult mice, which resulted in increased energy expenditure and reduced adiposity (Bartolomucci et al., 2006). Because the lean, hypermetabolic phenotype of germline VGF knockout mice is to a great extent recapitulated in Syn-Cre+/-,Vgfflpflox/flpflox mice, we conclude that the metabolic profile of germline VGF knockout mice is largely the result of VGF ablation in embryonic CNS neurons, rather than peripheral endocrine and/or neuroendocrine cells, and that in forebrain structures such as hypothalamus, VGF and/or VGF-derived peptides play uniquely different roles in the developing and adult nervous system.

Keywords: Adipose; Brain-derived neurotrophic factor (BDNF); Chromogranin; Diet-induced obesity; Energy expenditure; Hypothalamus; Neuropeptide; Secretogranin; Synapsin-Cre; VGF (non-acronymic).

Figures

Figure 1
Figure 1. Immunohistochemical analysis of hypothalamic, hippocampal, and cortical VGF protein expression in male conditional knockout Syn-Cre,Vgfflpflox/flpflox mice
Adult male 4 month old Syn-Cre,Vgfflpflox/flpflox (panels B, D, F, H; scale bar 50 µm) and age- and sex-matched control Syn-Cre,+/+ (panels A, C, E, G) mice were perfused, sectioned and immunohistochemically stained for VGF as described in ‘Materials and Methods’. Staining with DAPI is shown in the adjacent photomicrographs (panels A’–H’). Brain regions stained by anti-VGF588–617 (anti-AQEE-30) (Chakraborty et al., 2006) are as follows: hypothalamus, including suprachiasmatic nucleus (SCN) (panels A–B), paraventricular nucleus of the hypothalamus (PVH) (panels C–D), and arcuate nucleus (ARC) (panels E–F); hippocampus (HC) (panels G–H); and cerebral cortex (CC) (somatosensory cortex layers 1 and 2/3) (panels I–J).
Figure 2
Figure 2. Metabolic analysis of adult male Syn-Cre,Vgfflpflox/flpflox mice fed a standard diet
Body weight (panel A), body composition including fat mass normalized to body weight (panel B) and lean mass normalized to body weight (panel C), energy expenditure (panel D), respiratory exchange ratio (RER) (panel E), food intake (panel F), and locomotor activity (panel G), were measured in Syn-Cre,Vgfflpflox/flpflox and wild type (+/+,Vgfflpflox/flpflox), (+/+,+/+), or (Syn-Cre,+/+) male mice, fed a standard diet. Cohort sizes analyzed in panels A-C are shown above panel C, and in panels D-G, above panel E. Panel A. Body weight data was analyzed by ANOVA with Bonferroni post hoc analysis, (3,43) = 57.64 (P < 0.0001; ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panels B and C. Body fat and lean mass normalized to body weight data were analyzed by ANOVA with Bonferroni post hoc analysis (n.s.). Panel D–G. Energy expenditure, RER, food intake, and locomotor activity data were analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox and Syn-Cre,Vgfflpflox/flpflox, respectively (***, P<0.001).
Figure 3
Figure 3. Metabolic analysis of adult female Syn-Cre,Vgfflpflox/flpflox mice fed a standard diet
Body weight (panel A), body composition including fat mass normalized to body weight (panel B) and lean mass normalized to body weight (panel C), energy expenditure (panel D), respiratory exchange ratio (RER) (panel E), food intake (panel F), and locomotor activity (panel G), were measured in Syn-Cre,Vgfflpflox/flpflox and wild type [(+/+,Vgfflpflox/flpflox) or (Syn-Cre,+/+)] female mice, fed a standard diet. Cohort sizes analyzed in panels A–F are shown above panel C, and in panel G, above panel G. Panel A. Body weight data was analyzed by ANOVA with Bonferroni post hoc analysis, F (2,24) = 25.67 (P < 0.0001; ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panels B and C. Body fat and lean mass normalized to body weight data were analyzed by ANOVA with Bonferroni post hoc analysis (n.s.). Panel D–G. Energy expenditure, RER, food intake and locomotor activity data were analyzed by ANOVA with Bonferroni’s post hoc analysis between +/+, Vgfflpflox/flpflox and Syn-Cre,Vgfflpflox/flpflox, respectively (**, P<0.01; ***, P<0.001).
Figure 4
Figure 4. Metabolic analysis of adult male Syn-Cre,Vgfflpflox/flpflox mice fed a high-fat diet (HFD)
Body weight change over 6 weeks in mice fed a high fat diet (HFD) (panel A) was measured weekly, starting at 8–11 weeks of age, in Syn-Cre,Vgfflpflox/flpflox and wild type [(+/+,Vgfflpflox/flpflox), (Syn-Cre,+/+), or (+/+,+/+)] male mice. In panel B, body weights of 12–14 week old wild type and Syn-Cre,Vgfflpflox/flpflox mice fed STD or HFD for 6 weeks are compared. After mice had completed 6 – 10 weeks on HFD, starting at 8–11 weeks of age, body weight (panel C), body composition including fat mass normalized to body weight (panel D) and lean mass normalized to body weight (panel E), energy expenditure (panel F), respiratory exchange ratio (RER) (panel G), food intake (panel H), and locomotor activity (panel I), were measured in Vgfflpflox/flpflox,Syn-Cre and wild type [(Vgfflpflox/flpflox,+/+), (Syn-Cre,+/+), or (+/+,+/+)] male mice. Cohort sizes analyzed in panels A, and C–H are shown above panel A. Panel A. Body weight change over 6 weeks on HFD was analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox and Syn-Cre,Vgfflpflox/flpflox (***, P<0.001). Panel B. Body weights on STD or HFD were analyzed by ANOVA with Bonferroni post hoc analysis (*, P<0.05, **, P<0.01, ***, P<0.001). Cohort sizes: STD: (+/+, +/+ = 6; Syn-Cre,Vgf+/+= 9; +/+,Vgfflpflox/flpflox = 13; Syn-Cre,Vgfflpflox/flpflox = 7), HFD: (+/+, +/+ = 2; Syn-Cre,Vgf+/+= 3; +/+,Vgfflpflox/flpflox = 6; Syn-Cre,Vgfflpflox/flpflox = 6). Panel C. Body weight data was analyzed by ANOVA with Bonferroni post hoc analysis, F (3,20) = 33.65 (P < 0.0001; **, P<0.01; ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panel D. Body fat mass normalized to body weight was analyzed by ANOVA with Bonferroni post hoc analysis, F (3,20) = 14.46 (P < 0.0001; *, P<0.05; **, P<0.01; ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panel E. Body lean mass normalized to body weight was analyzed by ANOVA with Bonferroni post hoc analysis F (3,20) = 16.06 (P < 0.0001; *, P<0.05; **, P<0.01; ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panels F–H. Energy expenditure, RER and food intake data were analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox and Syn-Cre,Vgfflpflox/flpflox respectively (**, P<0.01; ***, P<0.001). Panel I. Locomotor activity data was analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox (n=9) and Syn-Cre,Vgfflpflox/flpflox (n=7) (***, P<0.001).
Figure 5
Figure 5. Metabolic analysis of adult female Vgfflpflox/flpflox,Syn-Cre mice fed a high-fat diet (HFD)
Body weight change over 6 weeks on a high fat diet (HFD) (panel A) was measured weekly, starting at 8–11 weeks of age, in Syn-Cre,Vgfflpflox/flpflox and wild type [(+/+,Vgfflpflox/flpflox) or (Syn-Cre,+/+)] female mice. In panel B, body weights of 9–14 week old wild type and Syn-Cre,Vgfflpflox/flpflox mice fed STD or HFD for 6 weeks are compared. After mice had completed 6 – 10 weeks on HFD, starting at 8–11 weeks of age, body weight (panel C), body composition including fat mass normalized to body weight (panel D) and lean mass normalized to body weight (panel E), energy expenditure (panel F), respiratory exchange ratio (RER) (panel G), food intake (panel H), and locomotor activity (panel I), were measured in Syn-Cre,Vgfflpflox/flpflox and wild type [(+/+,Vgfflpflox/flpflox) or (Syn-Cre,+/+)] female mice. Cohort sizes analyzed in panels A, and C-H, are shown above panel A. Panel A. Body weight change over 6 weeks on HFD was analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox and Syn-Cre,Vgfflpflox/flpflox (*, P<0.05; **, P<0.01; ***, P<0.001). Panel B. Body weights on STD or HFD were analyzed by ANOVA with Bonferroni post hoc analysis (***, P<0.001). Cohort sizes: STD: (Syn-Cre,Vgf+/+= 5; +/+,Vgfflpflox/flpflox = 5; Syn-Cre,Vgfflpflox/flpflox = 10), HFD: (Syn-Cre,+/+= 2; +/+,Vgfflpflox/flpflox = 3; Syn-Cre,Vgfflpflox/flpflox = 3). Panel C. Body weight data was analyzed by ANOVA with Bonferroni post hoc analysis, F (2,10) = 16.29 (P = 0.0007, ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panel D. Body fat mass normalized to body weight was analyzed by ANOVA with Bonferroni post hoc analysis, F (2,10) = 10.06 (P = 0.004; **, P<0.01 vs Syn-Cre,Vgfflpflox/flpflox). Panel E. Body lean mass normalized to body weight data was analyzed by ANOVA with Bonferroni’s post hoc analysis F (2,10) = 56.95 (P < 0.0001; *, P<0.05; **, P<0.01; ***, P < 0.001 vs Syn-Cre,Vgfflpflox/flpflox). Panel F–H. Energy expenditure, RER and food intake data were analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox and Syn-Cre,Vgfflpflox/flpflox respectively (***, P<0.001). Panel I. Locomotor activity data were analyzed by ANOVA with Bonferroni post hoc analysis between +/+, Vgfflpflox/flpflox (n=2) and Syn-Cre,Vgfflpflox/flpflox (n=3) (ns).

Similar articles

See all similar articles

Cited by 2 articles

Feedback