We have located links that may give you full text access.
JOURNAL ARTICLE
RESEARCH SUPPORT, NON-U.S. GOV'T
Standardizing protocols dealing with growth hormone receptor gene disruption in mice using the Cre-lox system.
Growth Hormone & IGF Research 2018 October
OBJECTIVE: Mice and humans with reduced growth hormone (GH) action before birth are conferred positive health- and life-span advantages. However, little work has been performed to study the effect of conditional disruption of GH action in adult life. With this as our objective, we sought to elucidate a reproducible protocol that allows generation of adult mice with a global disruption of the GH receptor (Ghr) gene, using the tamoxifen (TAM)-inducible Cre-lox system, driven by the ROSA26 enhancer/promoter. Here we report the optimum conditions for the gene disruption.
DESIGN: Six month old mice, homozygous for the ROSA26-Cre and the Ghr-floxed gene, were injected, once daily for five days with four distinct TAM doses (from 0.08 to 0.32 mg of TAM/g of body weight). To evaluate the most effective TAM dose that leads to global disruption of the GHR, mRNA expression of the Ghr and insulin growth factor-1 (Igf1) genes were assessed in liver, adipose tissue, kidney, and skeletal and cardiac muscles of experimental and control mice. Additionally, serum GH and IGF-1 levels were evaluated one month after TAM injections in both, TAM-treated and TAM-untreated control mice.
RESULTS: A dose of 0.25 mg of TAM/g of body weight was sufficient to significantly reduce the Ghr and Igf1 expression levels in the liver, fat, kidney, and skeletal and cardiac muscle of six-month old mice that are homozygous for the Ghr floxed gene and Cre recombinase. The reduction of the Ghr mRNA levels of the TAM-treated mice was variable between tissues, with liver and adipose tissue showing the lowest and skeletal and cardiac muscle the highest levels of Ghr gene expression when compared to control mice. Moreover, liver tissue showed the 'best' Ghr gene disruption, resulting in decreased total circulating IGF-1 levels while GH levels were increased versus control mice.
CONCLUSION: The results show that in mice at six months of age, a total TAM dose of at least 0.25 mg of TAM/g of body weight is needed for a global downregulation of Ghr gene expression with a regimen of 100 μL intraperitoneal (ip) TAM injections, once daily for five consecutive days. Furthermore, we found that even though this system does not achieve an equivalent disruption of the Ghr between tissues, the circulating IGF-1 is >95% decreased. This work helped to create adult mice with a global GHR knockdown.
DESIGN: Six month old mice, homozygous for the ROSA26-Cre and the Ghr-floxed gene, were injected, once daily for five days with four distinct TAM doses (from 0.08 to 0.32 mg of TAM/g of body weight). To evaluate the most effective TAM dose that leads to global disruption of the GHR, mRNA expression of the Ghr and insulin growth factor-1 (Igf1) genes were assessed in liver, adipose tissue, kidney, and skeletal and cardiac muscles of experimental and control mice. Additionally, serum GH and IGF-1 levels were evaluated one month after TAM injections in both, TAM-treated and TAM-untreated control mice.
RESULTS: A dose of 0.25 mg of TAM/g of body weight was sufficient to significantly reduce the Ghr and Igf1 expression levels in the liver, fat, kidney, and skeletal and cardiac muscle of six-month old mice that are homozygous for the Ghr floxed gene and Cre recombinase. The reduction of the Ghr mRNA levels of the TAM-treated mice was variable between tissues, with liver and adipose tissue showing the lowest and skeletal and cardiac muscle the highest levels of Ghr gene expression when compared to control mice. Moreover, liver tissue showed the 'best' Ghr gene disruption, resulting in decreased total circulating IGF-1 levels while GH levels were increased versus control mice.
CONCLUSION: The results show that in mice at six months of age, a total TAM dose of at least 0.25 mg of TAM/g of body weight is needed for a global downregulation of Ghr gene expression with a regimen of 100 μL intraperitoneal (ip) TAM injections, once daily for five consecutive days. Furthermore, we found that even though this system does not achieve an equivalent disruption of the Ghr between tissues, the circulating IGF-1 is >95% decreased. This work helped to create adult mice with a global GHR knockdown.
Full text links
Related Resources
Trending Papers
Heart failure with preserved ejection fraction: diagnosis, risk assessment, and treatment.Clinical Research in Cardiology : Official Journal of the German Cardiac Society 2024 April 12
Proximal versus distal diuretics in congestive heart failure.Nephrology, Dialysis, Transplantation 2024 Februrary 30
Efficacy and safety of pharmacotherapy in chronic insomnia: A review of clinical guidelines and case reports.Mental Health Clinician 2023 October
World Health Organization and International Consensus Classification of eosinophilic disorders: 2024 update on diagnosis, risk stratification, and management.American Journal of Hematology 2024 March 30
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app