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Source: http://www.doksinet Biochemistry of the Human Orgasm BY Yossr BERLOW Abstract Recent research suggests that there is substantial evidence that specific hormones and neurotnmsmitters directly influence the various aspects of human o,gasm. Clinical and experimental studies have linked a number ofhonnones and neurotmnsmitters to specific Jeatures ofthe 01gasm, including chemicals ofo,gasmic excitement, peak, and pleasure, as well as those that inhibit sexual desire. With this knowledge, insights into the origin and solution ófsexual problems and disorders may be gained. Unfortunately, a detailed map of the biochemistry of the o,gasm is stíl! far away Howeve,; researchers have begun to explain the basic ingredients of the intricate series ofhormonal and neuron a! events that produce one ofthe most pleasumble experiences in the world, o,gasm. The human orgasm is an intricace baller of hormonal and neuronal chemisrry producing whar is arguably one of rhe mosr pleasurable

experiences avai lable ro human beings. While people have been fascinarcd by orgasms for abour as long as rhey have been a species, ir is only in recent years rhar rescarchers have begun ro learn whar chis phenomenon is all abour ara biochemical levei. Today, rherc is su bstanrial evidence chac specific hormones and neurotransmirrers direcrly influcnce rhe various aspects of orgasm. For example, oxycocin, which has recenrly becn rouced by rhe popular media as che love hormone, is released during orgasm and appears ro be an essenrial facror modifying rhe inrensiry experienced. Similarly, endorphins, rhc endogenous brain opiates, arc also chought ro conrribure ro rhe pleasurable scnsarions. On che ocher hand , prolacrin, which is released righr afcer orgasm, accs ro inhibic che desirc for addicional sexual engagement. Examples such as rhese are chc beginning of a vcry crudc biochemical map rhar will add ro che undersrand ing of normal sexual performance as well as shed lighr onro sexual

dysfuncrion. What is an Orgasm? Websrer defines an orgasm as rhc climax of sexual exciremenr char is usually accompanied by rhe ejaculacion of semcn in che male and vaginal conrracrions in che Source: http://www.doksinet 134 THE LEHIGH REVIEW female. From chac simple definicion ic would seem chac Webscer discingu ishes orgasm from che physiological processes chac ofren come wich ic. This discinccion is somecimes difficult co cake inco accounc when accempting co figure out the complexicies of orgasm, because many scudies rely solely on che physical characceriscics of the phenomenon , not co memion che difficulcy in asking a mouse, "Was it good for you? " However, dividing orgasm imo experiemial and physiological componencs precedes an even greater division becween orgasm and the general sexual response. According co Mascers and Johnson, the typical sexual response includes phases of excicemem, placeau, orgasm and resolucion, usually in chat order (alternacive syscems use

che cerms desire, arousal, and orgasm) (Mescon & Frohlich, 2000). With che underscanding that orgasm, as defined above, rarely exiscs withouc che preceding scages of sexual response, dissecting influences of sexual excicemenc from those of climax becomes very difficulc. However, chere are cimes when che sexual response is halced right before orgasm and similarly chere are cases of orgasm occurring spomaneously, suggescing chat the orgasm is a discinct evenc. Nonecheless, it is a relacively shorc evenc chac is complicated to pin poinc. As a resulc, chis paper focuses on hormones and neurotransmitters influencing the rising accion, che climax and the resolucion of the orgasm and attempts co focus on the experiencial side of che process, buc somecimes chese are imprecise discinccions. Hormone Speclflclty The ocher major introduccory note thac has co be made is chac every hormone and neurocransmitter plays a very complex role, which requires che imeraction of many other components.

Reducing a subscance co one characteristic, such as referring co oxycocin as the love hormone, inaccuracely simplifies the elaborate sicuacion. Furthermore, many hormones will produce differem effeccs depending on many subde changes, such thac the difference becween too licde, coo much and jusc righc may not be linear. Having said this, ic should also be noted that che complex biochemical pathways and inceraccions of orgasm have not been fully developed and for simplifying purposes, many hormones and neurotransmitters will be referred co as chough chey each have a separate role. Background lnfluences: Sex Hormones and Viagra Most of the early sex research revolved around the so-called sex hormones, androgens and escrogens. Back chen, che primary incerest was focused on hormonal influence of sexual desire rather chan orgasm. Androgens such as cescoscerone appear co be influencial and important faccors in sexual desire, behavior and performance (Bancroft, 1983; Mescon & Frohlich,

2000; Sherwin et al. , 1985) However, androgen levels do not change dramacically during che various srages of sex and orgasm, indicacing they are noc che primary faccors involved in orgasm (Exton et al ., 1998, 1999) ln concrast, estrogens and progescerone are thoughc co have only minor effeccs on sexual desire and activicy (Mescon & Frohlich, 2000) and levels of these hormones also do not change much during sex (Excon ec al., 1999; Kruger ec al , 1998) Source: http://www.doksinet Yoss1 BERLOW 135 Anocher chemical chac is necessary for che earlier stages of sexual response is nicric oxide, which is secreced inco che penis (and clitoris) in response co sexual scimulacion. Nicric oxide signals che release of che enzyme guanylace cylase chac convercs guanosine criphophace inco cyclic guanosine monophosphare (cGMP). cGMP is responsible for che smooch muscle relaxacion rhac allows greacer blood Row co rhe penis producing an ereccion (a similar pachway has been suggesced in che

clitoris). Viagra, a medicacion for ereccile dysfunccion, works by inhibicing cGMP mecabolism (Mescon & Frohlich, 2000). The sceroid hormones along wich nicric oxide are clearly imporcanc ingrediencs for moving one chrough che excicemenc and placeau phases chac usually precede orgasm. While rhese background inAuences rnighc even be necessary for orgasm , chey are not che direcc concribucors. Orher subscances, including seroconin, cacecholamines, m-ycocin, endorphins etc, also inRuence rhese early scages, bur rhese chemicals appear co have a direcc role in producing orgasm. The Rising Action: Catecholamines, Serotonin and Premature Ejaculation At some poinc in che placeau srage, che hearcbeac quickens, blood pressure rises, and che sympachecic nervous syscem curns up irs levei of incensiry. The peak of orgasm is on ics way. This heighcening scace of arousal mighc be comparable co che expericnce of scress or anxiery commonly referred co as che fighc or Righc response Nor

surprisingly, ic appears chac che same hormones involved during scress, namely rhe cacecholamines epinephrine (adrenaline) and norepinephrine, also are involved in che excicing qualiry of orgasm. Catecholamines Some srudies have shown chac epinephrine levels increase during che excirement and placeau phases and peak ac orgasm and chen recurn co baseline (Excon ec al., 1999; Mescon & Frohlich, 2000). However chese changes in epinephrine are noc as greac as che changes in norepinephrine levels around che orgasm, which can be up co a 12-fold increase (Excon ec al. , 1999,2000; Kruger ec al, 1998; Mcscon & Frohlich, 2000; Wiedeking ec al., 1979) One scudy demonscraced how sympachecic arousal via exercise beforehand would not only increase norepinephrine levels, bur also increase vagina! pulse amplirude and vaginal blood volume (Mescon & Gorzalka, 1996). Furchermore, drugs chac increase norepinephrine acciviry, such as yohimbine and che ancidepressanc mirrazapine, have been

shown co de~rease sexual problems (Mescon & Frohlich, 2000). Norepinephrine appears co direcrly inRuence che exciring qualiry of orgasm. Serotonln Seroconins role in orgasm is much more complicaced. Increased seroconin acriviry has long been known co cause sexual side effeccs such as reduced desire and inhibiced orgasm in people using seleccive seroconin reupcake inhibicors. However, chese same Source: http://www.doksinet 136 THE LEHIGH REVIEW drugs have been used co prevenc premacure ejaculacion. Some researchers suggesc thac two differenc seroconin recepcors affecc sexual funccion in opposing ways. This indicaces chac chere is a delicace balance of seroco nin necessary for norma! sexual funccioning, coo liccle or coo much in che wrong placc leads co problems (Mescon & Frohlich, 2000). The Climax: Oxytocin, Opiates, Dopamine and Bliss As norepinephrine levels concinue co rise increasing che incensicy of che sexual , experience co a peak, there chen comes a blissful

release of cension and a rush of pleasure. ln men, seminal vessels ofcen begin co concracc ac orgasm, ejaculacing semen from the penis. Women display a similar series of concraccions in che ucerus Ac che same cime, oxycocin molecules arc released inco che blood along wich endorphins, creacing a discincc feeling of euphoria. Oxytocin An orgasm would probably noc be very enjoyable if ic were noc for oxycocin, che so-called love hormone. Oxycocin has been shown co be involved wich most posicive social inceraccions such as pair bonding and accachmcnc (Carcer, 1998; Uvnas-Moberg, 1998). le is also well known for ics role in birch and breascfecding (Odenc, 2000) Loving couches, massage and sexual arousal also raise blood levels of oxycocin above baseline (Turner ec al., 1999), buc chis is noching compared co che levels reached ac orgasm (Blaicher ec al., 1999; Carmichael ec al, 1987; Odenc, 2000; Riley, 1988) Oxycocin is released from che poscerior picuicary inco che blood ac orgasm where ic

exercs a sedacive, relaxing and posicive effecc. Cacecholamine levels and blood pressure drop in response co ic (Uvnas-Mohberg, 1998). The effecc of raising excicemenc and arousal via increased levels of cacecholamines and then flooding che syscem wich che anci-scress hormone oxycocin produces a rapid and exaggeraced feeling of euphoric concrasc, and some researchers have linked oxycocin levels wich che perceived incensicy of orgasm (Mescon & Frohlich, 2000). However, oxycocin does much morc than jusc creace exaggeraced relaxacion; ic also affeccs che endorphin syscem producing an opiace like high. Endorphlns Heroin users ofcen compare che opiace high co an orgasm, and ic would noc be surprising if endogenous opioids were involved. However, che levei ofinvolvemenc is noc clear. Some researchers have found no significanc increase in endorphin levels in che blood du ring orgasm (Excon ec al., 1999, Kruger ec al, 1998), buc chis does noc necessarily mean chey arc noc involved in che

cencral nervous syscem . Heroin users ofcen experience serious sexual side effeccs including inabilicy co achieve orgasm, while opiace wichdrawal has been known co cause sponcaneous orgasms (Mescon & Frohlich, 2000). This suggescs thac disrupcion of che endorphin sysrem clearly affeccs orgasm, indicacing chac endorphins arc involved. Source: http://www.doksinet Yoss, BERLow 137 Evidence suggests that endorphin involvement in orgasm is linked ro O>.}tocin release, but it is uncerrain how the rwo inreracr One study demonstrated that naloxone, an endorphin anragonist, prevenred O>-}t0cin release at orgasm (Murphy et al. , 1990) While other studies have shown oxytocin injections increase endogenous opioid production (Uvnas-Moberg, 1998). Another study has revealed that oxyrocin can inhibit tolerance formation ro morphine, meaning that the same amounr conrinues ro gives the same response (Kovacs et al., 1998) Clearly, there is some complex inreraction berween these rwo

hormones. Dopamine and Reinforcement ln order to get a better understanding of the probable role of oxyrocin and endorphins, it is helpful ro consider currenr models of reinforcemenr and learning concerning opiate addiction. lngesting drugs or performing any action that facilitates dopamine secretion from the venrral tegmenral nucleus inro the nucleus accumbens is said ro be a reinforcing act (Carlson, 1998) . From a Darwinian perspective it would make sense that orgasm would be such a reinforcing act, because it promotes continuation of the species. (Also, from a behaviorist perspective the fact that orgasms are not always achieved makes them one of the most effective reward systems for increasing sexual behavior.) ln animal studies, a place preference experiment is ofren used ro determine reinforcemenr, the idea being that if the animal moves from his preferred location in order ro perform some act, that act is reinforcing. Researchers have shown that ejaculacion in rats produces

reinforcemenr in the place preference paradigm. Furrhermore, they have shown that naloxone, the endorphin anragonist, blocks the reinforcing properties of ejaculation (Agmo & Berenfeld, 1990). This evidence furrher demonsrraces thac endorphins play an imporranc role in orgasm. Resolution: After the Fireworks comes Prolactin Right afrer che release of cension and the pleasure of climax, the hearrbeat slows, blood drains from the genitals and a period of relaxation begins. Some people might want ro go for another round, but most find it difficulr. This is probably because high levels of prolactin have been secreted into their blood. Prolactin Ifoxyrocin is the love hormone, prolactin is che "not now, honey" hormone. Prolaccin has been shown ro be associated wich decreased sexual desire and function (Mesron & Frohlich, 2000; Mulvihill, 2000). Prolactin has also been shown ro be released in great quanricy afrer orgasm (Excon et al., 1999, 2000; Kruger et al, 1998)

Researcher Michael Exron and colleges recent!y made the popular press with che announcemenr chac a prolactin surge released afrer orgasm diminishes the desire for sex. ln multiple studies (Exron et al, 1999,2000; Kruger et al, 1998), chey have found chac one of the biggest hormonal changes is the dramatic increase in prolactin afrer orgasm. One study (Exron, 2000) brought men and women close ro orgasm, Source: http://www.doksinet 138 THE LEHIGH REVIEW bur rhis was nor enough ro induce rhe prolacrin surge, indicaring prolacrin release is orgasm dependenr. However, as was poinred out in Psychology Today, rhis surge, which is seen in borh men and women, does not explain rhe sexually asymmerrical rendency or abiliry rowards mulriple orgasms, especially because women produce morc prolacrin rhan men (Pirisi, 2000). Obviously, morc research is needed Conclusion The inrricacies of orgasm remain somewhar of a mysrery, bur science is getring closer ro undersranding rhe underlying

biochemiscry rhar produces chis wonderful phenomenon. The paradoxical exciremenr/pleasure/relaxarion experience is beginning ro make some sense when we invesrigare rhe hormones and neurorransmirrers involved . Exciring adrenaline gives way ro pleasurable o>.-yrocin that stimulaces endogenous opioids, creating an inrense and life-creating evenc and before rhe dust seccles prolacrin comes in ro make sure people do not overdo it. Of course, it is nor ar all rhat simple, but rhese basic concepts will evenrually lead ro a morc complere understanding of rhe orgasm and sexual funcrion . References Agmo, A., & Berenfeld, R, (1990) Reinforcing propercies of ejaculacion in rhe male rat: role of opioids and dopamine. Behavioml Neuroscience, 104(1), 177-1 82. Bancrofr, J., Sanders, D, Davidson, D, & Warner, P (1983) Mood, sexualiry, hormones and rhe menstrual cycle. III sexualiry and che role of androgens . Psychosomatic Medicine, 45(6), 509-516 Blaicher, W., Gruber, D, Bieglmayer, C,

Blaicher, A M , Knogler, W, & Huber, J. C (1999) the role of oxytocin in relation ro female sexual arousal. Gynecological Obstetrics lnvest, 47(2), 125-126 Carmichael, M. S, Humberr, R Dixen, J, Palmisano , G , Greenleaf, W, & Davidson, J.M (1987) Plasma oxytocin increase in che human sexual response. journal of Clinical Endocrinology Metabolism, 64(!), 27-3 1 Carter, C. S, (I 998) Neuroendocrine perspecrives on social attachment and love . Psychoneuroendocrinology, 23(8), 779-8 18 Exton, M. S, Binderc, A, Kruger, T, Scheller, F, Harcman, U, & Schedlowski, M. (1999) Cardiovascular and endocrine alterations afrer masturbarion-induced orgasm in women. Psychosomatic Medicine, 61 (3), 280-289. Source: http://www.doksinet Yoss1 BERLOW 139 Excon, N. G, Truong, T C, Excon M S, W ingenfeld, S A, Leygraf, N, Saller, B., Hartmann, U , & Schedlowski , M (2000) Neuroendocrine response co film-induced sexual arousal in men and women. Psychoneuroend ocrinology, 2.5(2), 187-

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