GHSR/Growth hormone secretagogue receptor

The pulsatile nature of GH release is apparently regulated by alternating sequential changes in two hypothalamic hormones, GH releasing hormone (GHRH) and somatostatin. Entrainment of this pulsatility appears to involve GH-mediated negative feedback. Recently a new receptor involved in GH release was cloned. Activation of this receptor by GH-releasing peptides and MK-0677 initiates and amplifies GH pulsatility and is associated with increased Fos immunoreactivity and electrical activity in GHRH containing arcuate neurons. We show that pretreating mice with GH blocks activation of these neurons by MK-0677. Similarly, octreotide inhibited the action of MK-0677. To determine whether this GH-mediated negative feedback on GHRH neurons was direct, or by GH stimulation of somatostatin release from periventricular neurons, we selectively inactivated the gene for one of the five specific somatostatin receptor subtypes (subtype 2)[2].

Elevation in circulating GH levels results in a dose-related increase in serum insulin-like growth factor-1 (IGF-1) levels in dogs. However, it is not known whether elevations in systemic IGF-1 and GH levels contribute to the cerebrospinal fluid (CSF) levels of these hormones. Therefore, a study was designed in dogs to determine if elevated circulating GH levels was a result of a GH secretagogue (MK-0677) or if exogenous GH administration resulted in increased IGF-1 and GH levels in the CSF of dogs. A total of 12 normal, young adult male dogs were randomized to three treatment groups (4 dogs/group) based on body weight. There were 4 vehicle control dogs. A group of 4 dogs were dosed orally with MK-0677 (5 mg/kg/day) dissolved in deionized water. A third group of 4 dogs received subcutaneous injections of porcine GH (pGH) at a dose of 0.1 IU/kg/day. From all dogs, blood and CSF samples were collected prior to the initiation of treatment and on days 7 and 15 of treatment. All samples were assayed using a validated radioimmunoassay. Administration of MK-0677 or pGH resulted in a statistically significant (P < or = 0.05) increased body weight gain and increased serum IGF-1 and GH levels. In contrast, administration of MK-0677 resulted in no significant (P > 0.05) increase in CSF IGF-1 or GH levels on days 7 or 15 of the study. The CSF IGF-1 values ranged from 1.2 to 2.0 ng/ml with minimal variation among three separate samples taken during the course of the study from each dog. Similarly, the CSF GH levels were very low (< 0.98 ng/ml to 2.4 ng/ml) in all dogs irrespective of treatment group. This study has demonstrated that there is no correlation between the circulating levels of IGF-1 or GH and the levels of these hormones in the CSF of normal dogs. An approximately 100-fold difference between serum and CSF IGF-1 levels in vehicle control dogs suggest that there is a blood-brain barrier for the circulating IGF-1. Similarly, failure to see an elevation in CSF GH levels despite increases in serum GH levels shows that there is a blood-brain barrier for GH in normal dogs. These results suggest that the likely source of GH and IGF-1 in the CSF of dogs is from the CNS[2].

Compounds used were: MK-0677 (50 μg), octreotide (100 μg), and mGH (30 μg). Mice were give an initial ip injection (0.1 ml) of either saline, octreotide or mGH, followed 10 min later by an ip injection (0.1 ml) of either saline or MK-0677. Thus, the first study comprised of the following groups: saline/saline, saline/MK-0677, mGH/saline, mGH/MK-0677 saline/saline, saline/MK-0677, mGH/saline, mGH/MK-0677, and the second study of: saline/saline, saline/MK-0677, octreotide/saline, octreotide/MK-0677. Additionally, a number of mice were injected ip with hypertonic saline (0.2 ml, 1.5 M) to serve as positive controls for the immunocytochemistry. Ninety minutes after injection animals were terminally anesthetized with sodium pentobarbitone (60 mg/kg; ip) and perfused transcardially with heparinized saline followed by 4% paraformaldehyde in 0.1 M phosphate buffer (PB, pH 7.4). Brains were then removed and placed in the same solution for 24 h before being stored at− 80 C until processing. Coronal sections of forebrain (40 μm) were cut on a freezing microtome and placed in 0.1 M PB containing Triton X-100 (PB-T, pH 7.4). Sections were incubated for 24 h at 4 C in Ab-2 Fos antibody (rabbit polyclonal; 1:1000 in 1% normal sheep serum). The antibody-antigen complex was localized with a 1-h incubation in biotinylated anti-rabbit Ig (1:100), followed by a 1-h incubation in avidin, biotinylated horseradish peroxidase (1:50). The reaction product was visualized using a glucose oxidase-diaminobenzidine-nickel method, and Fos-like immunoreactivity was visualized as a dense purple-black precipitate restricted to the nucleus. The number of c-fos positive nuclei in the arcuate and periventricular nuclei (six to eight sections per mouse) were counted double-blind and a group mean calculated (mean ± SEM). Statistical analysis was performed by a two- way ANOVA followed by an all pairwise multiple comparison of data (Student-Newman-Keuls method) with significance taken as P < 0.05.[1]

[1]. Horm Metab Res . 1999 Feb-Mar;31(2-3):133-7.

[2]. Mol Endocrinol . 1997 Oct;11(11):1709-17.

Ibutamoren Mesylate is the mesylate salt form of ibutamoren, an orally bioavailable, small molecule, non-peptide growth hormone secretagogue (GHS). Upon administration, ibutamoren promotes the release of growth hormone (GH) from the pituitary gland, thereby increasing plasma GH levels. This may counteract GH deficiency. GH plays an important role in many biological processes. See also: Ibutamoren (has active moiety).

C28H40N4O8S2

624.77

624.228

C, 53.83; H, 6.45; N, 8.97; O, 20.49; S, 10.26

159752-10-0

159752-10-0 (mesylate); 159634-47-6

6450830

White to light yellow solid powder

4.974

CC(C)(C(=O)N[C@H](COCC1=CC=CC=C1)C(=O)N2CCC3(CC2)CN(C4=CC=CC=C34)S(=O)(=O)C)N.CS(=O)(=O)O

DUGMCDWNXXFHDE-VZYDHVRKSA-N

InChI=1S/C27H36N4O5S.CH4O3S/c1-26(2,28)25(33)29-22(18-36-17-20-9-5-4-6-10-20)24(32)30-15-13-27(14-16-30)19-31(37(3,34)35)23-12-8-7-11-21(23)27;1-5(2,3)4/h4-12,22H,13-19,28H2,1-3H3,(H,29,33);1H3,(H,2,3,4)/t22-;/m1./s1

2-amino-2-methyl-N-[(2R)-1-(1-methylsulfonylspiro[2H-indole-3,4'-piperidine]-1'-yl)-1-oxo-3-(phenylmethoxy)propan-2-yl]propanamide mesylate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)