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Structure And Receptor Pharmacology — Deep Dive

By Editorial Desk · published 2026-05-11 · last reviewed 2026-06-30 · Faq

GHRH analogue comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.

Updated 2026-06-30. Numbers and descriptions here follow the published literature rather than marketing material.

Structure And Receptor Pharmacology

CJC-1295 belongs to a class of synthetic peptides modeled on growth hormone releasing hormone, a forty-four amino acid signal produced by the hypothalamus. The compound is built from the first twenty-nine residues of the natural sequence, with four substitutions introduced at positions 2, 8, 15 and 27. These changes were designed to slow enzymatic breakdown while preserving receptor activation. The result is a peptide that is shorter than native GHRH and considerably more resistant to ordinary clearance pathways in circulation.

Two related forms appear under the CJC-1295 name. The simpler analogue, commonly written as modified GRF(1-29), carries the four substitutions but no additional conjugation. The second form attaches a maleimidopropionic acid linker to a lysine residue, a modification frequently called the drug affinity complex. That linker reacts with the free thiol on serum albumin to form a covalent bond. Because albumin has a long residence time in blood, the conjugated peptide stays in circulation far longer than the unconjugated analogue.

Molecular Background and Naming

Two related forms circulate in technical discussion under the same family name. The original version carries a drug affinity complex (DAC) that binds covalently to serum albumin after administration, and this linkage substantially extends circulation time. A second form, frequently written as modified GRF(1-29) or CJC-1295 without DAC, lacks that linker and clears much faster. The naming is a frequent source of confusion because the shorthand CJC-1295 can refer to either form depending on the source. Reports sometimes fail to specify which variant was studied.

The peptide backbone includes a D-alanine at position two, which resists cleavage by dipeptidyl peptidase IV, and several other substitutions that reduce degradation. Its molecular weight is roughly 3.4 kDa without the linker and about 3.6 kDa with it. The molecule is water soluble and is normally supplied as a lyophilized powder. Precise sequence and mass values depend on which variant is described, so technical documents usually state the exact form being referenced.

Cjc-1295 at a glance

PropertyValueNotes
Peptide classSynthetic GHRH analogueBuilt on a 29 residue sequence
Primary targetGHRH receptor (GHRHR)Class B G protein coupled receptor
Unconjugated half lifeMinutesLimited by protease degradation
Key modificationFour residue substitutionsPositions 2, 8, 15 and 27
Common synonymModified GRF(1-29)Usually denotes the form without DAC

Receptor Action and Pharmacokinetics

Downstream of growth hormone, the liver and other tissues increase production of insulin-like growth factor 1, a mediator of many growth-promoting effects. Studies have documented elevated levels of both hormones after dosing, and the rise from the long-acting form persists longer than that produced by shorter-acting analogues. What remains unclear is whether sustained elevation of these markers translates into meaningful clinical benefit, and whether prolonged exposure carries risks that short trials could not detect.

CJC-1295 acts at the growth hormone-releasing hormone receptor, a G-protein-coupled receptor found on somatotroph cells in the anterior pituitary. Binding triggers a rise in cyclic AMP and calcium entry, which promotes release of stored growth hormone. Because the peptide mimics the body's own releasing hormone, it amplifies existing secretory pulses rather than driving continuous output. The size of the response therefore depends partly on the subject's own hormonal rhythm and feedback state.

The attached maleimide group explains the unusual duration of the DAC version. After injection it reacts with the thiol of cysteine-34 on serum albumin, forming a stable covalent bond. The resulting conjugate is too large for rapid kidney filtration and is shielded from many peptidases. Reported half-lives for this form reach several days, whereas the version without the group is cleared in roughly half an hour. That gap is the main pharmacological difference between the two.

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Mechanism and Pharmacokinetics

The albumin-binding version stays in circulation for days, because covalent attachment to serum albumin shields the peptide from rapid filtration and degradation. Reported half-lives for this form fall in the range of several days. The version without the linker is cleared in minutes, with estimates often near thirty minutes in animal work. These figures come from small studies and vary with assay method, species, and route, so they are best read as approximate rather than fixed constants.

Studies in this area generally track growth hormone pulses, insulin-like growth factor 1 concentrations, and occasionally body composition endpoints. Most published human data come from early, small trials, and questions about long-term effects remain open. Whether repeated exposure alters pituitary responsiveness over time is not settled. Analytical work relies on immunoassays for the hormones and on mass spectrometry for the peptide itself, because the two measurements answer different questions.

Background from the literature

== 3D computer graphics == In 1996, Gibson received a research position at the Centre for Image and Sound Research at Simon Fraser University to study anaglyph images. He exhibited some of these images at the 1995 Currents exhibition in Vancouver and in Victoria, British Columbia. In 1996, he built the world's first completely anaglyphic website. Between 2002 and 2004, he studied 3D lenticular printing for his master's degree. By 2006 he was publicly showing autostereoscopic prints. In 2007 he had a major exhibition of this work at the 3D Center of Art and Photography in Portland, Oregon. In February 2011 he exhibited six large lenticular prints at the Blim Gallery in Vancouver, Canada. These prints paid homage to six renowned religious leaders by revealing the penis of God within them.

Canadian National Capital Commission: The Gift of Tulips Archived 14 May 2012 at the Wayback Machine Bulb flower production » Tulip, International Flower Bulb Centre Tulip Picture Book, International Flower Bulb Centre

=== Physiological === The peripheral actions of oxytocin mainly reflect secretion from the pituitary gland. The behavioral effects of oxytocin are thought to reflect release from centrally projecting oxytocin neurons, different from those that project to the pituitary gland, or that are collaterals from them. Neurons express oxytocin receptors in many parts of the brain and spinal cord, including the amygdala, ventromedial hypothalamus, septum, nucleus accumbens, and brainstem. The distribution differs markedly between species. Furthermore, the distribution of these receptors changes during development and has been observed to change after parturition in the montane vole.

The overall cost-effectiveness of neonatal circumcision has also been studied in the United States, which has a different cost setting from Africa in areas such as public health infrastructure, availability of medications, and medical technology and the willingness to use it. A CDC study suggests that newborn circumcision is societally cost-effective in the U.S., based on its efficacy against the transmission of HIV alone during coitus, without considering any other benefits. The American Academy of Pediatrics (2012) recommends that neonatal circumcision in the U.S. be covered by third-party payers such as Medicaid and insurance. A 2014 review that considered reported benefits of circumcision such as reduced risks of HIV, HPV, and HSV-2 stated that circumcision is cost-effective in the U.S. and Africa and may result in health care savings. A 2014 literature review found significant gaps in the literature on male and female sexual health that must be addressed for the literature to be applicable to North American populations.

Sources: en.wikipedia.org

Reference notes

=== Spin transport === Graphene is considered an ideal material for spintronics due to its minimal spin–orbit interaction, the near absence of nuclear magnetic moments in carbon, and weak hyperfine interaction. Electrical injection and detection of spin current have been demonstrated up to room temperature, with spin coherence length exceeding 1 micrometer observed at this temperature. Control of spin current polarity via electrical gating has been achieved at low temperatures.

Thyroglobulin (Tg) acts as a substrate for the synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3), as well as the storage of the inactive forms of thyroid hormone and iodine within the follicular lumen of a thyroid follicle. Newly synthesized thyroid hormones (T3 and T4) exist as prohormonal modified tyrosine residues of thyroglobulin, which comprise the colloid within the follicle. When stimulated by thyroid stimulating hormone (TSH), the colloid of the follicular lumen is endocytosed into the surrounding thyroid follicular epithelial cells. When endosomes fuse with lysosomes in these cells, Tg is subsequently cleaved by proteases to release thyroglobulin from its T3 and T4 attachments. Because of the hydrophobic nature of T3 and T4, they are able to then diffuse across the lysosomal membrane and into the cytoplasm. The active forms of thyroid hormone (T3 and T4), are then released into circulation where they are either unbound or attached to plasma proteins. Iodine is recycled back into the follicular lumen where it can continue to serve as a substrate for thyroid hormone synthesis, while the non-modified residues of Tg reenter cellular metabolic pathways.

Two different types of experiments were conducted: one-stepwise pyrolysis and two-stepwise pyrolysis. One-stepwise pyrolysis consisted of a constant heating rate (10 °C min−1) from 30 to 720 °C. In the second step of the two-stepwise pyrolysis test the pyrolysates from the one-stepwise pyrolysis were pyrolyzed in the second heating zone which was controlled isothermally at 650 °C. The two-stepwise pyrolysis was used to focus primarily on how well CO2 affects carbon redistribution when adding heat through the second heating zone. First noted was the thermolytic behaviors of TLW and TSW in both the CO2 and N2 environments. For both TLW and TSW the thermolytic behaviors were identical at less than or equal to 660 °C in the CO2 and N2 environments. The differences between the environments start to occur when temperatures increase above 660 °C and the residual mass percentages significantly decrease in the CO2 environment compared to that in the N2 environment. This observation is likely due to the Boudouard reaction, where we see spontaneous gasification happening when temperatures exceed 710 °C. Although these observations were seen at temperatures lower than 710 °C it is most likely due to the catalytic capabilities of inorganics in TLW. It was further investigated by doing ICP-OES measurements and found that a fifth of the residual mass percentage was Ca species. CaCO3 is used in cigarette papers and filter material, leading to the explanation that degradation of CaCO3 causes pure CO2 reacting with CaO in a dynamic equilibrium state.

== Pharmacokinetics == The major source of retinoids in the human diet is plant pigments such as carotenes and retinyl esters derived from animal sources. Retinyl esters are transported through the chylomicron pathway to the liver or fat tissue while retinol or carotenes are transported from the enterocytes to the liver and are processed into retinyl esters by LRAT for storage. Most synthetic retinoids are absorbed when taken orally, while topical retinoids cannot diffuse through the skin barrier unless it is compromised. All classes of retinoid bind to many proteins. Natural retinoids such as retinol and retinyl esters bind to carrier proteins such as RBP4, chylomicrons and VLDL while synthetic retinoids likely bind to these and other proteins. First generation retinoids are rapidly metabolized by Cytochrome p450 enzymes, typically of the Cyp26 family.

== Physiological roles == Myo-Inositol plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, the various inositol phosphates. Glycosylated inositol phosphates (or inositol phosphate glycans, IPGs) are produced by cells exposed to insulin and mediate a range of its blood glucose-regulating outcomes. Inositol also serves as an important component of the structural lipids phosphatidylinositol (PI) and its various phosphates, the phosphatidylinositol phosphate (PIP) lipids. Glycophosphatidylinositol (or GPI), a glycosylated derivative of phosphatidylinositol formed with the sugar nucleotide UDP-GalNAc and the fatty acids palmitate or myristate, provides the anchor to which many peripheral membrane proteins are attached to cell membranes, defining the category GPI-anchored proteins.

Sources: en.wikipedia.org

Frequently asked questions

Is CJC-1295 the same as modified GRF(1-29)?

The names are often used interchangeably in casual writing, but they are not strictly identical. Modified GRF(1-29) refers to the unconjugated analogue carrying only the four substitutions. The version sold as CJC-1295 with DAC includes the albumin binding linker and clears much more slowly.

What does the acronym DAC refer to?

DAC stands for drug affinity complex, a term describing the maleimidopropionic acid linker. This group forms a covalent bond with the cysteine residue on serum albumin after administration. The resulting adduct is what extends the circulating half life from minutes to days.

Does this peptide occur naturally in the body?

No. It is entirely synthetic and does not correspond to any known endogenous peptide. The design starts from human growth hormone releasing hormone and introduces deliberate substitutions. Any biological effect comes from mimicking the natural hormone at its receptor.

Is CJC-1295 a natural hormone?

No. It is a synthetic analogue modeled on the first 29 residues of human GHRH. The substitutions and any linker are laboratory modifications rather than features of the endogenous peptide.

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