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Thread: Would 50mcg IGF-1 LR3 4-5 times a week for 4 weeks be enough?

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  1. #1
    Join Date
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    research on mice shows lr3 igf1 does work better than igf1, and effect does not affacted by age
    quote:
    "We wished to determine whether sustained IGF-I production in skeletal muscle increases local IGF binding protein (IGFBP) abundance, thereby mitigating the long-term stimulation of muscle growth by IGF-I. Muscle growth of transgenic mice that overexpress IGF-I in muscle (SIS2) and of wild-type (Wt) mice was compared. At 3, 5, 10, and 20 wk of age, hind-limb muscle weights and IGFBP-3, -4, -5, and -6 mRNA and protein abundances were quantified. Additional mice were injected with IGF-I or LR3-IGF-I, and phosphorylation of the type 1 IGF receptor (IGF-1R) was compared. Muscle mass was 20% greater in SIS2 compared with Wt mice by 10 wk of age (P < 0.01), and this difference was maintained to 20 wk. IGFBP mRNA and protein abundances were unaffected by genotype. IGFBP-4 and -5 protein abundances increased with age, whereas for IGFBP-3 and -6, there was a sexual dimorphic response (P < 0.01); after 5 wk of age, IGFBP-3 decreased in males but increased in females, whereas IGFBP-6 decreased in females and remained unchanged in males. These protein expression patterns resulted from differences at both the transcriptional and posttranscriptional levels. LR3-IGF-I stimulated IGF-1R phosphorylation to a greater extent than IGF-I at both 5 and 10 wk of age (P < 0.01), regardless of gender or genotype (P > 0.21). Thus, variations in local IGF-I levels do not appear to regulate muscle IGFBP expression. The age- and gender-specific differences in muscle IGFBP expression are not sufficient to alter the response of the muscle to the IGFs but may impact the IGF-independent effects of these IGFBPs."

    another quote:

    The insulin-like growth factor (IGF) system is a complex network, including ligands (IGF-I and -II), binding proteins (IGFBP-1 to -6), and receptors, of which the type I IGF receptor (IGF-I-R) is important for transmission of most biological effects of IGFs. As IGFs are secreted in large amounts by the female reproductive tract, it has been hypothesized that maternal IGFs may affect embryonic growth and differentiation in a fine-tuned manner, involving modulation of IGF effects by embryonic IGFBP and IGF-I-R expression. To address this point, we cultured in vitro produced bovine embryos in a chemically defined culture system in the presence (100 ng/ml) of recombinant human IGF-I, long R3IGF-I (LR3), or without IGF supplementation (control). The affinity of LR3 to IGFBPs measured by competition assays and Western ligand blots is at least 3 orders of magnitude lower than that of IGF-I. LR3 was most efficient in stimulating early embryonic cleavage, whereas further development was most potently supported by IGF-I. Total cell numbers of blastocysts were highest in the presence of LR3 (105 +/- 4), followed by IGF-I (96 +/- 5), and the control group (91 +/- 3; P < 0.05). Differential cell staining of blastocysts revealed that these differences were mainly represented by trophectoderm cell numbers. Analysis of messenger RNA (mRNA) expression for IGFBPs and IGF-I-R was performed by RT-real-time PCR, using expression of the nonregulated housekeeping gene glyceraldehyde-3-phosphate dehydrogenase for normalization. Embryonic IGFBP-2 mRNA levels in the LR3 treatment group were 1.7-fold (P < 0.001) and 2.8-fold (P < 0.001) higher than those in the IGF-I and control groups, respectively. IGFBP-5 mRNA levels were about 2-fold (P < 0.001) elevated in both IGF treatment groups, with slightly (P < 0.05) higher levels in IGF-I- than in LR3-treated embryos. Similarly, IGFBP-3 mRNA abundance was increased (P < 0.05) in embryos from the IGF-I vs. the LR3 culture system. IGF-I-R mRNA levels were reduced by IGF-I (80% of control; P < 0.01), but increased by LR3 (1.3-fold vs. control; P < 0.001). These data show that the affinity for IGFBPs of IGF peptides is relevant for their effects on preimplantation embryos and affects different parameters, i.e. development, cell numbers, and mRNA expression for components of the IGF system, in different directions.
    Last edited by seanL; 06-13-2008 at 11:38 PM.

  2. #2
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    Quote Originally Posted by seanL View Post
    research on mice shows lr3 igf1 does work better than igf1, and effect does not affacted by age
    .
    Really? Show me human studies to prove this!

    Human metabolism is not even remotely the same as that of mice. Just because something works in an animal does not mean it will work in humans. There are countless studies to show that.

    Further, research further in regards to mice and LR3. and you'll find studies showing extreme liver damage with mice. Even death! Yea, it works better...

    Another wishful thinker.....

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