A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavior of the receiving individuals. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology.
The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth in various tetrapods. The name is derived from the fact that it lies adjacent to the unpaired vomer bone in the nasal septum. It is present and functional in all snakes and lizards, and in many mammals, including cats, dogs, cattle, pigs, and some primates. Some humans may have physical remnants of a VNO, but it is vestigial and non-functional.
The flehmen response, also called the flehmen position, flehmen reaction, flehmen grimace, flehming, or flehmening, is a behavior in which an animal curls back its upper lip exposing its front teeth, inhales with the nostrils usually closed, and then often holds this position for several seconds. It may be performed over a sight or substance of particular interest to the animal, or may be performed with the neck stretched and the head held high in the air.
Androstenedione, or 4-androstenedione, also known as androst-4-ene-3,17-dione, is an endogenous weak androgen steroid hormone and intermediate in the biosynthesis of estrone and of testosterone from dehydroepiandrosterone (DHEA). It is closely related to androstenediol (androst-5-ene-3β,17β-diol).
Androstenone (5α-androst-16-en-3-one) is a steroidal pheromone. It is found in boar's saliva, celery cytoplasm, and truffle fungus. Androstenone was the first mammalian pheromone to be identified. It is found in high concentrations in the saliva of male pigs, and, when inhaled by a female pig that is in heat, results in the female assuming the mating stance. Androstenone is the active ingredient in 'Boarmate', a commercial product made by DuPont sold to pig farmers to test sows for timing of artificial insemination.
Androstenediol, or 5-androstenediol, also known as androst-5-ene-3β,17β-diol, is an endogenous weak androgen and estrogen steroid hormone and intermediate in the biosynthesis of testosterone from dehydroepiandrosterone (DHEA). It is closely related to androstenedione (androst-4-ene-3,17-dione).
Epitestosterone, or isotestosterone, also known as 17α-testosterone or as androst-4-en-17α-ol-3-one, is an endogenous steroid and an epimer of the androgen sex hormone testosterone. It is a weak competitive antagonist of the androgen receptor (AR) and a potent 5α-reductase inhibitor.
Trestolone, also known as 7α-methyl-19-nortestosterone (MENT), is an experimental androgen/anabolic steroid (AAS) and progestogen medication which has been under development for potential use as a form of hormonal birth control for men and in androgen replacement therapy for low testosterone levels in men but has never been marketed for medical use. It is given as an implant that is placed into fat. As trestolone acetate, an androgen ester and prodrug of trestolone, the medication can also be given by injection into muscle.
Androstadienone, also known as androsta-4,16-dien-3-one, is an endogenous steroid that has been described as having potent pheromone-like activities in humans. The compound is synthesized from androstadienol by 3β-hydroxysteroid dehydrogenase, and can be converted into androstenone by 5α-reductase, which can subsequently be converted into 3α-androstenol or 3β-androstenol by 3-ketosteroid reductase.
Atamestane, also known as metandroden, as well as 1-methylandrosta-1,4-diene-3,17-dione, is a steroidal aromatase inhibitor that was studied in the treatment of cancer. It blocks the production of estrogen in the body. The drug is selective, competitive, and irreversible in its inhibition of aromatase.
Charles J. Wysocki, Ph.D., is a biologist and psychologist, and an emeritus member of the Monell Chemical Senses Center. He is notable for his work with the genetics of olfaction in mice and humans, the vomeronasal organ and the major histocompatibility complex. He has worked with Drs. George Preti and Gary Beauchamp in the past.
Epiandrosterone, or isoandrosterone, also known as 3β-androsterone, 3β-hydroxy-5α-androstan-17-one, or 5α-androstan-3β-ol-17-one, is a steroid hormone with weak androgenic activity. It is a metabolite of testosterone and dihydrotestosterone (DHT). It was first isolated in 1931, by Adolf Friedrich Johann Butenandt and Kurt Tscherning. They distilled over 17,000 litres of male urine, from which they got 50 milligrams of crystalline androsterone, which was sufficient to find that the chemical formula was very similar to estrone.
Vomeronasal receptors are a class of olfactory receptors that putatively function as receptors for pheromones. Pheromones have evolved in all animal phyla, to signal sex and dominance status, and are responsible for stereotypical social and sexual behaviour among members of the same species. In mammals, these chemical signals are believed to be detected primarily by the vomeronasal organ (VNO), a chemosensory organ located at the base of the nasal septum.
Odour is sensory stimulation of the olfactory membrane of the nose by a group of molecules. Certain body odours are connected to human sexual attraction. Humans can make use of body odour subconsciously to identify whether a potential mate will pass on favourable traits to their offspring. Body odour may provide significant cues about the genetic quality, health and reproductive success of a potential mate. Body odour affects sexual attraction in a number of ways including through human biology, the menstrual cycle and fluctuating asymmetry. The olfactory membrane plays a role in smelling and subconsciously assessing another human's pheromones. It also affects the sexual attraction of insects and mammals. The major histocompatibility complex genes are important for the immune system, and appear to play a role in sexual attraction via body odour. Studies have shown that body odor is strongly connected with attraction in heterosexual females. The women in one study ranked body odor as more important for attraction than “looks”. Humans may not simply depend on visual and verbal senses to be attracted to a possible partner/mate.
7-Ketodehydroepiandrosterone (7-keto-DHEA,7-oxo-DHEA), also known as 7-oxoprasterone, is a prohormone produced by metabolism of the prohormone dehydroepiandrosterone (DHEA).
Cyproterone, also known by its developmental code name SH-80881, is a steroidal antiandrogen which was studied in the 1960s and 1970s but was never introduced for medical use. It is an analogue of cyproterone acetate (CPA), an antiandrogen, progestin, and antigonadotropin which was introduced instead of cyproterone and is widely used as a medication. Cyproterone and CPA were among the first antiandrogens to be developed.
The Great Pheromone Myth is a book on pheromones and their application to chemosensation in mammals by Richard Doty, director of the University of Pennsylvania's Smell and Taste Center in Philadelphia. Doty argues that the concept of pheromone introduced by Karlson and Lüscher is too simple for mammalian chemonsensory systems, failing to take into account learning and the context-dependence of chemosensation. In this book, he is especially critical of human pheromones, arguing that not only are there no definitive studies finding human pheromones, but that humans lack a functional vomeronasal organ to detect pheromones. Its publication received coverage in the news media, especially concerning its arguments that human pheromones do not exist.
3α-Androstanediol glucuronide (3α-ADG) is a metabolite formed from human androgens; compounds involved in the development and maintenance of sexual characteristics. It is formed by the glucuronidation of both dihydrotestosterone and testosterone, and has been proposed as means of measuring androgenic activity.
Pherines, also known as vomeropherines, are odorless synthetic neuroactive steroids that engage nasal chemosensory receptors and induce dose-dependent and reversible pharmacological and behavioral effects. Pherines target human chemosensory receptors and possibly other receptors such as the GABAA receptor and influence central nervous system activity.
Ro 6-3129, also known as 16α-ethylthio-6-dehydroretroprogesterone or as 16α-ethylthio-9β,10α-pregna-4,6-diene-3,20-dione, as well as 16α-ethylthiodydrogesterone, is a progestogen of the retroprogesterone group which was developed by Roche but was never marketed. It shows greater potency than dydrogesterone in bioassays.
