The short version of MC4 receptor fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-30 and is reviewed periodically as new material appears.
PT-141 is the original development code for bremelanotide, a synthetic peptide first studied as a potential tanning and sexual-response agent in the 1990s. Researchers at a small American biotechnology firm designed it as a shortened analogue of melanotan II, which itself came from work on alpha-melanocyte-stimulating hormone. Early screening focused on pigmentation, but behavioural observations in animal models redirected attention toward sexual motivation. That shift made PT-141 one of the first melanocortin compounds investigated specifically for effects on desire rather than on skin colour.
Clinical development proceeded through two routes of administration. An intranasal formulation advanced first, but variable absorption and tolerability problems led to a switch to subcutaneous injection. The United States Food and Drug Administration approved the subcutaneous product in 2019 for hypoactive sexual desire disorder in premenopausal women. Marketing rights subsequently changed hands, and commercial availability has fluctuated since approval. Use in men, in postmenopausal women, and in combination with other agents remains outside the approved label.
Outside the approved product, bremelanotide circulates as a research chemical sold by peptide vendors, often labelled PT-141. Such material is not manufactured under pharmaceutical quality standards, and independent testing has repeatedly found content that differs from the label. Analytical certificates supplied with a purchase are not strong evidence of purity because they are usually generated by the seller. Online discussion tends to blur the distinction between the approved drug and unregulated powder, which complicates interpretation of reported experiences.
Reverse-phase high-performance liquid chromatography is the standard method for assessing purity. Mass spectrometry confirms molecular identity and detects sequence variants or truncation products. Ultraviolet absorbance at 214 or 280 nm is used for quantification, with the choice depending on the peptide sequence. Method validation typically addresses linearity, limit of detection, and precision across a defined concentration range. Impurity profiling may also employ ion-exchange or size-exclusion chromatography, and these techniques complement one another.
Certificate of analysis documents usually report purity percentage, molecular weight, and appearance. Researchers verify identity by comparing observed and theoretical mass values. Chain-of-custody records and batch numbers help trace material from source to experiment. Independent verification of supplier claims is considered good practice when material identity is critical to a study. Records should include the storage history of each aliquot, and unexpected deviations in appearance or solubility warrant re-testing before use.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H68N14O10 | Free base; the drug product is formulated as an acetate salt |
| Molar mass | About 1025 g/mol | Calculated for the free base |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| CAS Registry Number | 189691-06-3 | Common listing for the free base |
| Typical storage | -20 °C, desiccated, protected from light | Repeated freeze-thaw cycles are best avoided |
Whether the behavioral effect originates centrally, peripherally, or through both remains an active question. Animal experiments using receptor antagonists and site-specific injections point toward hypothalamic melanocortin circuits as a key locus, but translating those findings to humans is not straightforward. Blood pressure changes observed in trials suggest a vascular component that may be peripherally mediated. The relationship between receptor occupancy and reported effect has not been mapped in humans, and no validated biomarker predicts response. This gap makes it difficult to explain individual variability on pharmacological grounds alone.
Bremelanotide acts as an agonist at melanocortin receptors, a family of five G-protein-coupled receptors labeled MC1 through MC5. Binding studies indicate activity at several of these subtypes rather than strict selectivity for one. Signalling proceeds mainly through Gs-mediated activation of adenylyl cyclase, raising intracellular cyclic AMP. The MC4 receptor, expressed in hypothalamic and limbic circuits, is widely regarded as the subtype most relevant to sexual response. Because the molecule is not subtype-selective, effects at other melanocortin receptors are expected and are used to explain some observed side effects.
The peptide contains seven amino acids arranged in a ring, closed by a lactam bridge between a side-chain acid and an amine. This cyclic constraint holds the backbone in a defined conformation and increases resistance to enzymatic breakdown relative to linear analogs. N-terminal acetylation and a C-terminal amide further protect the molecule from exopeptidases. The result is a compound with a comparatively long circulation time for a small peptide. Structural modification of the bridge alters receptor affinity, which is one reason analogs in this family differ in their subtype preferences.
Reconstitution is usually performed with sterile water or a dilute acetic acid solution, and the choice of solvent affects both dissolution speed and final pH. Complete dissolution should be confirmed by visual inspection before any aliquot is taken, since undissolved particles can concentrate in the sampling volume. Repeated freeze-thaw cycles are the most common cause of gradual loss of purity, so dividing a stock into single-use aliquots at the first opportunity is standard practice. Working solutions kept refrigerated are generally used within days rather than weeks.
Identity and purity are established with orthogonal methods rather than a single test. Reverse-phase high-performance liquid chromatography with ultraviolet detection gives a purity figure by area normalization, while mass spectrometry confirms the expected molecular ion. Amino acid analysis or peptide mapping can detect sequence errors that a mass value alone would miss, and residual counterion content is sometimes measured separately. Common impurities include truncated sequences, oxidized residues, and deamidated products; reporting them individually is more informative than a single composite purity number.
The compound binds several melanocortin receptor subtypes rather than a single target, with the strongest functional activity reported at MC4R and measurable activity at MC1R, MC3R and MC5R. MC4R populations are dense in hypothalamic nuclei that integrate energy balance, autonomic tone and reproductive behaviour, which is the anatomical basis for the proposed pro-desire effect. Because binding is not subtype-selective, pigmentary and vascular effects accompany central activity. Improving subtype selectivity is an active area of analogue design. Direct causal mapping from receptor occupancy to reported desire change in humans is not fully established.
After subcutaneous dosing, peak plasma concentrations appear within roughly one hour, and elimination is fast, with a half-life on the order of a few hours. Degradation is mainly proteolytic, and at least one circulating fragment retains receptor activity, so parent-drug levels alone do not describe total exposure. Clearance does not depend heavily on hepatic cytochrome enzymes, which lowers the likelihood of common metabolic interaction routes. Data in renal or hepatic impairment are limited. Repeated dosing does not appear to produce marked accumulation given the short half-life.
=== Korea === Either dried kombu powder or julienned kombu (typically of the species Saccharina japonica) can be used to make the tea. Powdered tea can be made by pan-frying and pounding cleaned and dried kelp. For a cup of hot water, two to three spoons of kelp powder is used. Optionally, sugar or honey can be added. Alternatively, around 30 grams (1.1 oz) of cleaned kelp pieces are infused in 300–500 millilitres (11–18 imp fl oz; 10–17 US fl oz) of hot water. The kelp slices are removed after infusing, and salt is added to taste.
In 2004, a special issue of The International Journal of Sociology and Social Policy was published that was edited by Steven P. Schacht, who participated in the SSSP session. The special issue contained ten articles analyzing his research and his multiple contributions as a social activist and scholar. The authors of these articles call for sociologists and others to move beyond criticism of Humphrey's research methodologies in the tearoom study, and instead to focus on his pioneering contributions to the study of sexuality, participant-observation as method, development of sociological theory, and his work as a social activist and advocate for marginalized sexual identities.
==== Reagent coflow prior to droplet formation ==== Reagents can be added at the time of droplet formation through a "co-flow" geometry. Reagent streams are pumped in separate channels and join at the interface with a channel containing the continuous phase, which shears and creates droplets containing both reagents. By changing the flow rates in reagent channels, reagent ratios within a droplet can be controlled.
== Research and advocacy == The Muscular Dystrophy Association (MDA) is involved in research, advocacy, and services for individuals affected by muscular dystrophy. The organization provides resources that contribute to understanding and addressing this condition.
Sources: en.wikipedia.org
== Chestnut family colors == Chestnut is considered a "base color" in the discussion of equine coat color genetics. Additional coat colors based on chestnut are often described in terms of their relationship to chestnut:
At Adelaide, because of the absence of Professor Johnston, he was appointed Acting Chair of Zoology, as acting head of the department he organised the new department and its teaching. Here he was influenced by Wood Jones, Professor of Anatomy, and the physiologist Professor Brailsford Robertson, one of the pupils of Jacques Loeb. Oscar Tiegs spent three years at Adelaide, during which time he was granted a Bachelor of Science degree in 1922 and obtained his Doctorate of Science degree in 1922 both from the University of Adelaide, at the age of 25, his thesis being on the histology of metamorphosis of a pteromalid wasp (Nasonia), specifically Nasonia brevicornis (now designated Nasonia vitripennis). Oscar Tiegs' doctoral thesis work was to be the basis for much of his later work, in embryological studies, and the study of fine structures in muscle. He found clear evidence that the apparent striation of muscle fibres did not arise from separate disks, but from a helicoidal organisation within the fibre. He also found a similar condition in vertebrate muscles. Later he discovered that former histologists had recorded the same thing, but their observations had received little attention. He contended that helicoidal striation is a general feature of muscles and that muscular conduction takes place along this helicoidal path, even though the evidence for this generality was against him, yet his cinematographic records supported his interpretation for arachnids and other arthropods.
== History == Use of castor oil as a laxative is attested to in the c. 1550 BC Ebers Papyrus, and it was in use several centuries earlier. Midwifery manuals from the 19th century recommended castor oil and 10 drops of laudanum for relieving "false pains".
=== Infection === The use of greater amount of red blood cells has been suggested to increase the risk of infections, not only transfusion-transmitted infections, but also due to a phenomenon known as transfusion-related immunomodulation (TRIM). TRIM may be caused by macrophages and their byproducts. In those who were given red blood cells only with significant anemia ("restrictive" strategy), serious infection rates were 10.6% while in those who were given red blood at milder levels of anemia ("liberal" strategy), serious infection rates were 12.7%. On rare occasions, blood products are contaminated with bacteria. This can result in a life-threatening infection known as transfusion-transmitted bacterial infection. The risk of severe bacterial infection is estimated, as of 2020, at about 1 in 2,500 platelet transfusions, and 1 in 2,000,000 red blood cell transfusions. Blood product contamination, while rare, is still more common than actual infection. The reason platelets are more often contaminated than other blood products is that they are stored at room temperature for short periods of time. Contamination is also more common with longer duration of storage, especially if that means more than 5 days. Sources of contaminants include the donor's blood, donor's skin, phlebotomist's skin, and containers. Contaminating organisms vary greatly, and include skin flora, gut flora, and environmental organisms. There are many strategies in place at blood donation centers and laboratories to reduce the risk of contamination.
chemotaxis A directed, non-random change in the movement of a molecule, cell, or organism in response to a chemical stimulus, e.g. towards or away from an area with a high concentration of a particular chemical compound.
Sources: en.wikipedia.org
In 1983, the Democratic Socialists of America was founded as a merger of the Democratic Socialist Organizing Committee with the New American Movement, an organization of New Left veterans. Earlier in 1973, Michael Harrington and Irving Howe formed the Democratic Socialist Organizing Committee which articulated a democratic socialist message while a smaller faction associated with peace activist David McReynolds formed the Socialist Party USA. Harrington and the socialist-feminist author Barbara Ehrenreich were elected as the first co-chairs of the organisation which does not stand its own candidates in elections and instead "fights for reforms ... that will weaken the power of corporations and increase the power of working people." In Greece, the Panhellenic Socialist Movement, better known as PASOK, was founded on 3 September 1974 by Andreas Papandreou as a democratic socialist, left-wing nationalist, Venizelist and social democratic party following the collapse of the military dictatorship of 1967–1974. As a result of the 1981 legislative election, PASOK became Greece's first centre-left party to win a majority in the Hellenic Parliament and the party would later pass several important economic and social reforms that would reshape Greece in the years ahead until its collapse in the 2010s.
Dog saliva has been said by many cultures to have curative powers in people. "Langue de chien, langue de médecin" is a French saying meaning "A dog's tongue is a doctor's tongue", and a Latin quote that "Lingua canis dum lingit vulnus curat" or "A dog's saliva can heal your wound" appears in a thirteenth-century manuscript. In Ancient Greece, dogs at the shrine of Aesculapius were trained to lick patients, and snake saliva was also applied to wounds. Saint Roch in the Middle Ages was said to have been cured of a plague of sores by licking from his dog. The Assyrian Queen Semiramis is supposed to have attempted to resurrect the slain Armenian king Ara the Beautiful by having the dog god Aralez lick his wounds. In the Scottish Highlands in the nineteenth century, dog saliva was believed to be effective for treating wounds and sores. In the Gospel of Luke (16:19-31), Lazarus the Beggar's sores are licked by dogs, although no curative effects are reported by the Evangelist.
With osemozotan administration, the number of marbles buried was decreased with apparently little to no loss in motor coordination; these test results support the theory that osemozotan may be useful in the treatment of OCD. It has been noted that sensitization to cocaine may stem from action of the 5-HT1A receptor. While the role of 5-HT receptors with methamphetamine is still not certain, the use of osemozotan was found to decrease 5-HT levels in patients on repeated methamphetamine exposure; this may be a possibility for treatment of drug dependence with cocaine and methamphetamine.
{\displaystyle Q=\left[m_{\text{N}}\left({\ce {^{\mathit {A}}_{\mathit {Z}}X}}\right)+m_{\text{e}}-m_{\text{N}}\left({\ce {^{\mathit {A}}_{{\mathit {Z}}-1}X'}}\right)-m_{\nu _{\text{e}}}\right]c^{2},}
Sources: en.wikipedia.org
PT-141 is a research code for bremelanotide, a cyclic peptide that activates melanocortin receptors. It was developed for sexual dysfunction and later approved under a brand name as a subcutaneous injection. The same code is widely used by suppliers selling non-pharmaceutical material.
Both are synthetic melanocortin agonists and share a similar peptide backbone, but they are distinct molecules with different receptor profiles. Melanotan II was never approved as a medicine, whereas bremelanotide was. Findings about one compound should not be transferred to the other without direct evidence.
It is typically distributed as a lyophilized powder in sealed vials, sometimes with a separate solvent. Purity statements usually originate from the supplier rather than an independent laboratory. Storage recommendations vary between vendors, which makes comparison across sources difficult.
Storage at -20 °C or below is standard for long-term stability. Desiccant and sealed containers limit moisture exposure. Solutions are prepared only when needed.