Everything below concerns MC4R. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-06-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
Early clinical work used an intranasal formulation, and later programmes switched to subcutaneous delivery for more consistent absorption. A subcutaneous product received regulatory approval in the United States in 2019 for premenopausal women with acquired, generalised hypoactive sexual desire disorder. Approval followed phase 3 trials in which active treatment separated from placebo on desire and distress measures, though the average difference was modest. Labeling carries a caution about transient blood pressure elevation, so cardiovascular history is assessed before prescribing. Questions about durability of benefit beyond several months remain open.
Published discussion sits at the intersection of peptide chemistry, neuroendocrinology and sexual medicine. Trial reports emphasise change scores on validated instruments, while mechanistic papers focus on hypothalamic circuits and receptor selectivity. Because placebo response in this field is large, effect sizes are usually reported with confidence intervals rather than as isolated averages. Reviews note that female and male data sets are not interchangeable and should be read separately. Diagnostic terminology has been revised over time, which complicates comparison between older and newer studies.
The melanocortin system comprises five G protein-coupled receptors, designated MC1 through MC5, that signal mainly through cyclic AMP accumulation. MC1R and MC2R are associated with pigmentation and adrenal steroid production, while MC3R and MC4R are expressed in the central nervous system and influence energy balance and behavior. MC5R appears in exocrine tissues. Natural agonists include alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone, and endogenous antagonists such as agouti-related protein modulate the same sites. This receptor family provides the framework within which bremelanotide activity is described.
Bremelanotide acts as an agonist at several melanocortin receptors, with the strongest reported activity at MC4R and measurable activity at MC1R and MC3R. Because MC4R is expressed in hypothalamic and limbic circuits, the proposed mechanism links receptor activation to modulation of central pathways involved in desire rather than to direct effects on peripheral genital tissue. The precise downstream steps remain incompletely characterized, and evidence for the involvement of specific neurotransmitters is suggestive rather than settled. Nausea and blood pressure elevation reported during trials are consistent with melanocortin signaling outside the intended target circuit.
Compared with melanotan II, bremelanotide is a smaller cyclic peptide with a more constrained backbone, which affects receptor selectivity and metabolic stability. Published descriptions give a plasma half-life on the order of a few hours after subcutaneous administration, with elimination through hepatic and renal routes and limited plasma protein binding. Central access is inferred from effects observed in animal models, although direct measurement in humans is limited. Handling and storage requirements follow from the peptide backbone, which is susceptible to hydrolysis and oxidation.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-MSH |
| Molecular mass | Approximately 1025 Da | Peptide-scale molecule |
| Route | Subcutaneous injection | Intranasal form used in early research |
| Common synonyms | PT-141; bremelanotide acetate | Research code and salt form |
| Typical storage | 2-8 °C, protected from light | Unopened vial condition |
Early research on PT-141 grew out of work on melanotan II, a related cyclic peptide studied for pigmentation. Investigators observed that centrally acting melanocortin agonists also influenced sexual behaviour in animal models, and the programme shifted toward that endpoint. A nasal formulation was evaluated in clinical trials but showed inconsistent absorption, and later studies used subcutaneous administration instead. Regulatory approval in the United States followed in 2019 for a defined population of premenopausal women with acquired, generalised hypoactive sexual desire disorder. That approval was specific to that group rather than a broad indication.
Bremelanotide acts as a non-selective agonist at melanocortin receptors, with reported activity at MC1R, MC3R, MC4R and MC5R. The proposed basis for its central effects is activation of MC4R populations in the hypothalamus, a region associated with appetite and reproductive signalling. Because the peptide carries a net positive charge and polar side chains, it does not cross biological membranes freely, which is one reason oral administration is not the standard route. Effects generally appear within an hour of parenteral administration and are described as centrally mediated rather than peripheral.
Bremelanotide, developed under the code PT-141, is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone. Its structure is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, with a lactam bridge joining the aspartate and lysine side chains. The molecule has the formula C50H68N14O10 and a monoisotopic mass near 1025 daltons. It is commonly prepared as the acetate salt and appears as a white to off-white lyophilised powder in solid form. The free acid is the pharmacologically relevant species, while the counter-ion improves handling and dissolution.
=== Economy === The Culture is a symbiotic society of artificial intelligences (AIs) (Minds and drones), humanoids and other alien species who all share equal status. All essential work is performed (as far as possible) by non-sentient devices, freeing sentients to do only things that they enjoy (administrative work requiring sentience is undertaken by the AIs using a bare fraction of their mental power, or by people who take on the work out of free choice). As such, the Culture is a post-scarcity society, where technological advances ensure that no one lacks any material goods or services. Energy is farmed from a fictitious "energy grid", and matter to build orbitals is collected mostly from asteroids. As a consequence, the Culture has no need of economic constructs such as money (as is apparent when it deals with civilisations in which money is still important). The Culture rejects all forms of economics based on anything other than voluntary activity. "Money implies poverty" is a common saying in the Culture.
Although some worms have eyes (e.g. leeches, some polychaetes), earthworms do not. However, they do have specialized photosensitive cells called "light cells of Hess". These photoreceptor cells have a central intracellular cavity (phaosome) filled with microvilli. As well as the microvilli, there are several sensory cilia in the which are structurally independent of the microvilli. The photoreceptors are distributed in most parts of the epidermis, but are more concentrated on the back and sides of the worm. A relatively small number occur on the ventral surface of the first segment. They are most numerous in the prostomium, and reduce in density in the first three segments; they are very few in number past the third segment.
In solar water disinfection (often shortened as "sodis"), microbes are destroyed by temperature and UVA radiation provided by the sun. Water is placed in a transparent plastic PET bottle or plastic bag, oxygenated by shaking partially filled capped bottles prior to filling the bottles all the way, and left in the sun for 6–24 hours atop a reflective surface.
Sources: en.wikipedia.org
Cardiac troponin C (cTnC) TNNC1 is expressed in cardiac and slow skeletal muscle, while skeletal troponin C (sTnC) TNNC2 is expressed in fast skeletal muscle. sTnC has four calcium ion-binding sites, whereas in cTnC there are only three. The actual amount of calcium that binds to troponin has not been definitively established. Because slow skeletal muscle and myocardium share a type, TnC is not used in diagnostics. Mammals have three troponin I (TnI) genes: the cardiac (TNNI3, cTnI), the slow skeletal (TNNI1), and the fast skeletal (TNNI2). Because the heart uses its own version, blood levels of cTnI is used as a clinical marker. Mammals have three troponin T (TnT) genes: the cardiac (TNNT2, cTnT), the slow skeletal (TNNT1), and the fast skeletal (TNNT3). Again, because the heart uses its own version, cTnT is used as a clinical marker. In addition to the myocardium, there are reports of CTnI and CTnT expression in the wall muscle coat of the vena cava and pulmonary veins, so they do not purely originate from the heart. The expression of cTnT in skeletal tissue of patients with chronic skeletal muscle injuries has been described.
Referring to the Privy Council's decision that the UK might yet remove the post-UDI government, he said that "on the facts as they exist today, the only prediction which this court can make is that sanctions will not succeed in overthrowing the present government ... and that there are no other factors which might succeed in doing so". Macdonald, a member of Beadle's ruling panel, argued that since UDI, the British government had acted unconstitutionally and illegally regarding Rhodesia by involving the United Nations in what should have been legally considered a domestic problem, and had concurrently abdicated its right to the allegiance of the Rhodesian people by waging economic war against the country and encouraging other nations to do the same. To support this argument, Macdonald referred to the assertion by the 17th-century Dutch jurist Hugo Grotius that "the purpose of governing and the purpose of destroying cannot subsist together". Since Britain was in a state of economic war against Rhodesia, the court concluded, it could not at the same time be regarded as governing it. UDI, the associated 1965 constitution and the government were thereafter considered de jure by the Rhodesian legal system. The British Commonwealth Secretary, George Thomson, promptly accused the Rhodesian judges of breaching "the fundamental laws of the land", while Gibbs announced that since his position as Governor existed under the 1961 constitution, which allowed appeals to the Privy Council, he could only reject the Rhodesian court ruling. The Rhodesian judges continued regardless.
=== Historical === In 1888, the French botanist Gaston Bonnier demonstrated early experimental evidence for lichen symbiosis through his work with X. parietina (then called Parmelia parietina). He reported creating artificial lichen thalli by replacing the organism's natural algal partner (Protococcus viridis) with different algae species, including Protococcus botryoides and the filamentous reddish alga Trentepohlia abietina. While his methods foreshadowed modern microbiological techniques and represented a significant step for the time, modern assessments note critical limitations. His algal sources were not truly isolated (coming from other lichen thalli), and his "synthesized lichens" only vaguely resembled natural specimens, showing fungal hyphae surrounding algal cells but lacking true lichen morphology. In 1967, Richardson conducted early transplant experiments with X. parietina that helped establish methods for studying lichen adaptability. Using a novel technique of attaching lichen thalli to new substrates with resin glue, the study achieved a 96% survival rate in transplanted specimens. When coastal specimens (var. ectanea) were moved to farm roofs in Oxford, they showed significant morphological changes within 18 months, including increased lobe width from 0.8 mm to 2.4 mm. The study also demonstrated that parietin production could adapt to local conditions within six months, with transplanted specimens eventually matching the pigment levels of native populations.
== History == Pseudoephedrine, along with ephedrine, occurs naturally in ephedra. This herb has been used for thousands of years in traditional Chinese medicine. Pseudoephedrine was first isolated and characterized in 1889 by the German chemists Ladenburg and Oelschlägel, who used a sample that had been isolated from Ephedra vulgaris by the Merck pharmaceutical corporation of Darmstadt, Germany. It was first synthesized in the 1920s in Japan. Subsequently, pseudoephedrine was introduced for medical use as a decongestant.
Sources: en.wikipedia.org
== Contraindications == Phenelzine is contraindicated in patients who are unable or unwilling to follow the required dietary tyramine restrictions and medication precautions, and in patients with pheochromocytoma because of the risk of hypertensive emergency. This contraindication reflects a preventable risk: tyramine-related hypertensive emergencies are uncommon when dietary and medication precautions are followed, and modern food standards have substantially reduced excessive tyramine exposure compared with the period when MAOIs were first introduced. It is also contraindicated with drugs, supplements, or recreational drugs that have significant serotonin reuptake inhibition or significant serotonin-releasing activity, because of the risk of serotonin toxicity. Examples include selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs), clomipramine, imipramine, MDMA, and certain analgesics such as meperidine, tramadol, methadone, tapentadol, dextromethorphan, dextropropoxyphene, pentazocine, and levorphanol. Concomitant use of multiple MAO-inhibiting agents is generally listed as contraindicated or avoided in prescribing guidance. For combinations of classic MAOIs with one another, the caution is based mainly on limited safety data and the fact that routine long-term coadministration usually has little therapeutic rationale, since classic MAOIs already inhibit both MAO-A and MAO-B irreversibly.
Detention Centers run by the Assad government have been one of the most glaring human rights abuses in Syria. In 2014, the Caesar Report showed gruesome photographs smuggled out of a Syria detention center showed "the systematic killing of more than 11,000 detainees by the Syrian government in one region" during a two and a half year period of the Syria Civil War. A 2016 United Nations investigative report described the detainees in Syrian prisons as suffering under "inhuman living conditions" characterized by unclean environment, lack of sanitation and food as well as systematic torture. Following the death of prisoners in custody, fake certificates were often distributed by the government to claim that the prisoners "died of natural causes". The report further denounced Assad regime's policies of torture and summary executions in detention centres as "extermination as a crime against humanity". Syrian dungeons have been compared to the Nazi extermination camps of World War II, due to the scale of torture and mass killings going on in its prison networks. Journalist Russ Wellen reports that the "state killing machine exceeds the capacity of the system to process". In 2017 details emerged about Sednaya Prison, a military prison near Damascus operated by the Assad government. The prison has been used to hold thousands of prisoners, both civilian and government opposition. Amnesty International estimated that between 5,000 and 13,000 people were extrajudicially executed at the one prison between September 2011 and December 2015.
=== Wound healing === Because galectin-7 is mainly expressed in the stratified epithelia, it is considered a marker of the epidermis, oral cavity, cornea, esophagus, and anorectal epithelium tissues. The injury of corneal wounds causes an increase of sensitivity to receptors of galectin-7 in the cornea. The effect is then blocked by the beta lactose which suggests that the protein's CRD is involved in the stimulatory response to promote the closure of the wound. In a study conducted with mice where the galectin-7 protein was rendered non-functional, the mice were found to have delayed wound closure as the keratinocyte outgrowth was reduced. The study found that the protein localizes to podosomes, a surface in animals that is essential for cell migration and matrix remodeling, and affects the cortactin distribution. The cortactin is a protein that is widely distributed to cellular and in tissue structures which is correlated to the cell's morphology. This would suggest that the protein regulates actin-based lamellipodia formation, a form on the cell that drives cell migration. The kidney epithelial wound repair study found that a non-functional galectin-7 protein results in kidney epithelial cells having a shorter cilia and 33% reduced wound closure, found through various scratch tests. This all indicated how the galectin-7 protein also affects cilia structures and the wound healing process through simple epithelia. The uterine endometrial repair tests expressed how the protein is present and functional in late secretory and menstrual phases.
== Distinctions and honors == During his life, Jones was awarded 61 patents. Forty were for refrigeration equipment, while others were for devices for theater equipment and devices pertaining to gasoline engines.
The structure in this final region contains long, aligned lamellae that alternate between ice crystals and ceramic walls. The faster a sample is frozen, the finer its solvent crystals (and its eventual macroporosity) will be. Within the SSZ, the normal speeds which are usable for colloidal templating are 10 – 100 mm s−1 leading to solvent crystals typically between 2 mm and 200 mm. Subsequent sublimation of the ice within the SSZ yields a green ceramic preform with porosity in a nearly exact replica of these ice crystals. The microstructure of a freeze-cast within the SSZ is defined by its wavelength (λ) which is the average thickness of a single ceramic wall plus its adjacent macropore. Several publications have reported the effects of solidification kinetics on the microstructures of freeze-cast materials. It has been shown that λ follows an empirical power-law relationship with solidification velocity (υ) (Eq. 2.14):
Sources: en.wikipedia.org
It is a synthetic cyclic peptide that activates melanocortin receptors. It is given by injection and was approved in the United States in 2019 for a specific low-desire diagnosis in premenopausal women. It is not a hormonal therapy.
Earlier approaches were largely hormonal or psychological in focus, whereas this compound acts on central melanocortin signalling. It is not a vasodilator and does not share the mechanism of phosphodiesterase inhibitors. Head-to-head comparative data are limited.
Placebo responses in desire trials are large, so the average drug-placebo separation is small. Reporting therefore relies on validated questionnaires with statistical ranges. Individual responses vary widely.
Reported activity is highest at MC4R, with lower potency at MC1R and MC3R. The MC4R interaction is generally treated as the most relevant to its central effects. Selectivity is not absolute, and activity across the family is dose-dependent.