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Michael S. Exton áTillmann H. C. Kru
Èger áNorbert
Bursch áPhilip Haake áWolfram Knapp áManfred
Schedlowski áUwe Hartmann
Endocrine response to masturbation-induced orgasm in healthy men
following a 3-week sexual abstinence
Abstract This current study examined the eect of a
3-week period of sexual abstinence on the neuroen-
docrine response to masturbation-induced orgasm.
Hormonal and cardiovascular parameters were exam-
ined in ten healthy adult men during sexual arousal
and masturbation-induced orgasm. Blood was drawn
continuously and cardiovascular parameters were
constantly monitored. This procedure was conducted
for each participant twice, both before and after a
3-week period of sexual abstinence. Plasma was sub-
sequently analysed for concentrations of adrenaline,
noradrenaline, cortisol, prolactin, luteinizing hormone
and testosterone concentrations. Orgasm increased
blood pressure, heart rate, plasma catecholamines and
prolactin. These eects were observed both before and
after sexual abstinence. In contrast, although plasma
testosterone was unaltered by orgasm, higher testos-
terone concentrations were observed following the
period of abstinence. These data demonstrate that
acute abstinence does not change the neuroendocrine
response to orgasm but does produce elevated levels of
testosterone in males.
Key words Abstinence áSexual arousal áOrgasm á
Prolactin áCatecholamines áCortisol á
Testosterone áCardiovascular
Although sexual abstinence is a common behavioral
pattern in humans, there has been little examination of
the psychological and physiological consequences of this
behavior. Nevertheless, limited data have demonstrated
that sexual abstinence may impact on the physiological
regulation of sexual function. Speci®cally, retrospective
studies have shown that features of semen quality are
reduced during long periods of sexual abstinence [5, 22].
In contrast, periods of abstinence between 12 h and
10 days have generally revealed enhanced sperm quality
parameters [9, 26, 28, 33], although this is not consistent
across all measures of sperm quality [28, 33]. Neverthe-
less, acute sexual abstinence is commonly employed prior
to clinical sperm donation to enhance sperm quality.
Despite knowing that acute abstinence aects repro-
ductive function, no data exist that examines the eect
of abstinence on the physiological response to sexual
arousal and orgasm. We have established a method for
examining the neuroendocrine response to masturba-
tion-induced orgasm in men and women [15±17, 24],
based upon a continuous blood sampling technique.
These investigations demonstrated that masturbation-
induced orgasm produced a pronounced increase in
cardiovascular responses and plasma catecholamine
concentrations. Furthermore, sexual arousal was char-
acterised by a large, persistent increase in concentrations
of plasma prolactin. Since hyperprolactinemia is known
to inhibit sexual arousal and function [13, 35], these data
suggest that prolactin may act as a peripheral and/or
central feedback signal in controlling sexual arousal
following orgasm.
Therefore, the purpose of this current study was
to investigate the eect of acute abstinence on the
physiological response to sexual arousal. Speci®cally, we
World J Urol (2001) 19: 377±382 ÓSpringer-Verlag 2001
The ®rst two authors made equal contributions to this work. This
study was partially supported by a grant from the Deutsche Fors-
chungsgemeinschaft (Sche 341/10±1).
M. S. Exton (&)áT. H. C. Kru
Èger áP. Haake
M. Schedlowski
Institut fu
Èr Medizinische Psychologie,
Universita
Ètsklinikum Essen, Hufelandstr. 55,
45122 Essen, Germany
e-mail: michael.exton@uni-essen.de
Tel.: +49-201-723-4282; Fax: +49-201-723-5948
N. Bursch áU. Hartmann
Division of Clinical Psychiatry, Hannover Medical School,
30623 Hannover, Germany
W. Knapp
Division of Nuclear Medicine, Hannover Medical School,
30623 Hannover, Germany
examined the neuroendocrine responses to sexual
arousal and orgasm following separate periods of
regular sexual activity and sexual abstinence in healthy
men by using an established paradigm.
Materials and methods
Participants
Ten healthy male volunteers (mean age of 25.8 0.8 years, range
of 22±29 years) participated in this investigation. Participants were
screened by completing a general medical/health questionnaire and
gave their written consent before being admitted into the study. The
protocol for this study was approved by the Ethics Committee for
Investigations involving human subjects of the Hannover Medical
School, Germany. Individuals taking medication, abusing drugs/
alcohol, or exhibiting endocrinological, psychological or sexual
dysfunction/disorders were excluded from the study. All partici-
pants reported that they had an exclusively heterosexual orientation
and a relaxed attitude toward pornography. Further, all subjects
were currently in a stable relationship and reported having sexual
intercourse approximately 2±3 times per week.
Design and procedure
A repeated measures design was used so each participant viewed a
videotape and masturbated to orgasm on two separate days. Two
dierent videos were shown in a crossover design for the two
sessions. The ®rst session took place at 1630 hours on day 0.
Immediately after that ®rst session (day 0±day 20), the participant
refrained from any type of sexual activity. At 16:30 on day 21 each
subject once again participated in the sexual arousal paradigm. The
procedure of sexual arousal and orgasm both before (day 0) and
after (day 21) were identical, with each session lasting 2 h.
Experiments were conducted in a separate sound-attenuated
room equipped with a clinical bed, a color television and a video
cassette player. All leads, including the blood line, passed through
the wall into the adjacent room where the cardiovascular data and
blood samples were collected, allowing the subject to be completely
isolated throughout the experiment. At the beginning of each
session participants were placed on the bed in front of the video
screen. The cardiovascular monitor was then engaged 30 min prior
to the ®lm and a steady baseline reading was obtained before the
cannula was inserted (20 min before the beginning of the ®lm).
The session was composed of three sequences, each lasting 20 min.
The ®rst and last sections of the video tape were composed of
sections of an emotionally neutral documentary ®lm. However, the
middle section consisted of a 20 min pornographic ®lm that
showed dierent couples engaged in foreplay and sexual inter-
course. Blood sampling was initiated at the beginning of the ®lm.
After 10 min of the pornographic video had been watched (antic-
ipatory phase), subjects in the experimental session were required
to masturbate until orgasm. Blood was drawn continuously with
the samples divided into six 10 min intervals [15±17, 24]. Speci®-
cally, the ®rst two samples represented basal values (10, 20 min),
the third sample represented the response to ®lm-induced sexual
arousal (30 min), the fourth demonstrated the response to orgasm
(40 min) and the ®nal two samples showed the recovery phase (50,
60 min).
Apparatus and materials
Subjective sexual arousal
To provide a measurement for sexual arousal, participants com-
pleted a visual analogue scale (VAS) by rating their subjective level
of sexual arousal from `not at all sexually aroused' to `extremely
sexually aroused' [15±17, 24]. Subjective sexual arousal was mea-
sured at three time points±before, during and after the session±for
both controlled and experimental conditions.
Additionally, subjective assessment of the quality of the
orgasm was completed using 5-point Likert scales. These scales
examined the duration, intensity and speed of orgasm in absolute
value and as compared to a typical orgasm. These questions were
administered following both the experimental and controlled
situations.
Cardiovascular measures
The cardiovascular parameters heart rate (HR) and systolic and
diastolic blood pressure (BP) were monitored continuously via a
®nger cu connected to a blood pressure monitor (Critikon Cu &
Dinamap Vital Data Monitor; Critikon Ltd, USA) that was
located in the adjoining room. Cardiovascular activity was
recorded by computer every 30 s, and the HR and BP values were
averaged over 10 min intervals and analysed simultaneously with
the blood samples taken in 10 min interval.
Endocrine measures
For blood sampling, an IV cannula (Vaso®x Braunu
Èle, 18G) was
connected to a 1.25 m heparinized silicon tube (inner B2.0 mm,
Reichelt Chemie, Heidelberg, Germany) by a plastic three-way
stop-cock (Cook, Mo
Ènchengladbach, Germany). The silicon tubing
passed through the wall into the adjacent room and was positioned
through a peristaltic pump (Fresenius, Homburg, Germany). Blood
¯ow was adjusted to 2 ml/min, so that approximately 10 mls of
blood per 5 min were collected (i.e. more than 150 mls per session).
Blood was collected in EDTA tubes (Sarstedt, Nu
Èmbrecht,
Germany), and the collection of each sample was delayed by the
time it took for blood to pass through the dead space in the tube.
Blood was stored on ice until the samples were centrifuged. Plasma
was stored in glass aliquots at )20 °C until it was time for the
hormone assays.
All samples from the one participant were analysed in duplicate
within the same assay for a particular hormone. Plasma prolactin
was evaluated by immunoradiometric assay (IBL, Hamburg,
Germany) and testosterone, LH, cortisol (Diagnostic System
Laboratories, Texas, USA) and catecholamines (IBL, Hamburg,
Germany) were assessed by radioimmunoassay. Inter and intra-
assay variability were 8.0% and 6.2%, respectively, for noradren-
aline; 5.1% and 4.0%, respectively, for adrenaline; 7.1% and 5.0%,
respectively, for prolactin; 7.9% and 5.2%, respectively, for
testosterone; 5.2% and 3.8%, respectively, for LH; and 4.3% and
2.8%, respectively, for cortisol.
Statistical analyses
Data from all subjects were analysed by 2-factor repeated measures
(condition x time) analyses of variance (ANOVA). If not stated
otherwise, only the condition x time interaction eect is reported.
An alevel of 0.05 was used for all ANOVAs. Post hoc simple eects
were evaluated by using paired samples t-tests with Bonferroni a
corrections made for multiple comparisons. Additionally, the
Wilcoxon test was completed for questionnaire data.
Results
Subjective sexual arousal
Participants rated themselves as being signi®cantly
sexually aroused during the erotic ®lm (F(2, 16) 189.51,
P< 0.001; time eect) and greater subjective arousal
378
was observed following abstinence (F(1,8) 9.21,
P0.016; condition eect, Fig. 1a). Moreover, partici-
pants reported a longer duration (before, 2.1 0.3;
after, 3.5 0.3; Z )2.34, P0.019) and greater
intensity (before, 2.5 0.2; after, 3.7 0.3; Z )2.28,
P0.023) of orgasm following abstinence as compared
to the controlled session, whilst abstinence did not alter
the subjective speed to orgasm (before, 3.1 0.2; after,
3.5 0.2; Z )0.71, P> 0.05). Similar results were
revealed when subjects compared the orgasmic charac-
teristics to those of a typical orgasm (duration: before,
1.8 0.2; after, 3.1 0.4; Z )2.26, P0.023;
intensity: before, 2.1 0.2; after, 3.0 0.3; Z )1.73,
P0.080; speed: before, 3.1 0.2, after, 3.8 0.3;
Z)1.35, P> 0.05).
Prolactin, LH and testosterone response
to sexual arousal
Sexual arousal (timepoint: 30 min) and orgasm
(timepoint: 40 min) increased plasma prolactin levels
markedly in participants (F(5, 45) 5.80, P< 0.001;
time eect, Fig. 1b). However, no signi®cant dierence
was observed in this response before and after acute
abstinence (P> 0.05).
Sexual arousal (timepoint: 30 min) and masturba-
tion-induced orgasm (timepoint: 40 min) did not aect
testosterone concentrations either before or after absti-
nence (P> 0.05). However, a signi®cant increase in
basal testosterone levels were observed following the
period of abstinence (F(5, 45) 6.72, P0.029; con-
dition eect, Fig. 1c). A signi®cant dierence between
the conditions was observed at the 20 min baseline pe-
riod, with this dierence remaining throughout the ses-
sion. Increased testosterone was further accompanied by
a small increase in plasma LH following abstinence;
however this change did not reach statistical signi®cance
(P> 0.05; data not shown).
Cardiovascular response to sexual arousal
Sexual arousal (timepoint: 30 min) and orgasm
(timepoint: 40 min) increased heart rate (F(5, 45)
=14.18, P< 0.001; time eect), systolic blood pressure
(F(5, 45) 16.35, P< 0.001; time eect) and diastolic
blood pressure in participants (F(5, 45) 18.11,
P< 0.001; time eect, Fig. 2). However, no signi®cant
dierence was observed in any of these responses before
and after acute abstinence (all P> 0.05).
Sympathoadrenal response to sexual arousal
Sexual arousal (timepoint: 30 min) and orgasm (time-
point: 40 min) increased both adrenaline (F(5,45)
=7.95, P< 0.001; time eect) and noradrenaline
(F(5,45) 10.90, P< 0.001; time eect) in participants
(Fig. 3). However, no signi®cant dierence was observed
in either of these responses before and after acute ab-
stinence (P> 0.05). Sexual arousal and masturbation-
induced orgasm did not aect cortisol concentrations
either before or after abstinence. However, re¯ecting
circadian rhythm, cortisol levels decreased consistently
over time during both sessions (F(5, 45) 4.66,
P0.02; time eect).
Fig. 1a±c Subjective sexual arousal before, during and after sexual
arousal; plasma prolactin (ng/ml) and testosterone (ng/ml) concen-
trations during baseline (10, 20 min), in response to ®lm-induced
sexual arousal (30 min), following orgasm (40 min), and recovery
after orgasm (50, 60 min). Each subject participated before sexual
abstinence (h) and following 3 weeks of abstinence (j)(Data
displayed as mean SE). Subjective sexual arousal was increased
by masturbation-induced orgasm (a). Furthermore, this response was
enhanced following sexual abstinence. Plasma prolactin concentra-
tions (b) were signi®cantly elevated by sexual arousal and orgasm
both before and after sexual abstinence. In contrast, plasma
testosterone concentrations (c) were unaected by sexual arousal
and orgasm both before and after sexual abstinence. However, plasma
testosterone was signi®cantly elevated after abstinence when com-
pared to basal values (Data displayed as mean SE)
379
Discussion
The current study demonstrated that 3 weeks of sexual
abstinence elevated basal testosterone concentrations
and increased both subjective sexual arousal and sub-
jective interpretation of the quality of the orgasm.
However, despite these subjective reports, acute absti-
nence did not alter the well-characterised cardiovascular
and endocrine responses to orgasm.
Sexual arousal and masturbation-induced orgasm
produced pronounced increases in sympathetic activity,
which were re¯ected by increased heart rate, blood
pressure and plasma catecholamine concentrations.
Furthermore, orgasm produced a pronounced increase in
plasma prolactin concentrations. These results mirrored
previous data obtained by studying masturbation in
both men and women [15, 24], which have been shown
to be orgasm speci®c [16].
We have suggested that prolactin secretion following
orgasm may act as a peripheral and/or central feedback
signal in controlling post-orgasm sexual arousal. This
position is supported by a wealth of data from studies of
animals and humans that demonstrate the marked
inhibitory eect that hyperprolactinemia has on sexual
arousal and behavior [11, 13, 30, 32, 35], as well as a
decrease in inhibition following the normalization of
circulating prolactin [13, 35].
Prolactin may also act as an acute negative controller
of sexual function by inhibiting the function of sexual
Fig. 2a±c Cardiovascular activity during baseline (10, 20 min), in
response to ®lm-induced sexual arousal (30 min), following orgasm
(40 min) and recovery after orgasm (50, 60 min). Each subject
participated before sexual abstinence (h) and following 3 weeks of
abstinence (j) (Data displayed as mean SE). Heart rate (beats/
min; a), systolic blood pressure (mm Hg; b) and diastolic blood
pressure (mm Hg; c) were signi®cantly elevated by sexual arousal
and orgasm before and after sexual abstinence
Fig. 3a±c Plasma adrenaline (pg/ml), noradrenaline (pg/ml), and
cortisol (ng/ml) concentrations during baseline (10, 20 min), in
response to ®lm-induced sexual arousal (30 min), following orgasm
(40 min), and recovery after orgasm (50, 60 min). Each subject
participated before sexual abstinence (h) and following 3 weeks of
abstinence (j) (Data displayed as mean SE). Adrenaline (a)
and noradrenaline (b) concentrations were signi®cantly elevated by
sexual arousal and orgasm both before and after sexual abstinence.
In contract, plasma cortisol concentrations (c) were unaected by
sexual arousal and orgasm both before and after sexual abstinence
380
organs. Although not extensively examined, some data
clearly demonstrate that acute increases in prolactin
inhibit erectile function by hindering the smooth muscle
relaxation of the corpus cavernosum [4]. Alternatively,
acute increases in prolactin may contribute to a sexual-
satiation mechanism following orgasm by means of
feedback to the central nervous system (CNS) structures
that control sexual arousal [10, 21, 29].
Should prolactin act as a negative regulator of sexual
arousal, increased prolactin secretion may be expected
to accompany increased sexual arousal produced by
abstinence. However, the current data show that acute
abstinence does not alter the prolactin response to
masturbation-induced orgasm. Nevertheless, although it
is clear that the prolactin response is orgasm dependent,
the magnitude of the response may be independent of
the quality of the orgasm. Alternatively, the subjective
scores used presently may not provide an accurate
assessment of physiological quality of the orgasm. Thus,
future studies should incorporate a more complete
assessment of orgasm quality, by integrating a more
robust measurement of orgasmic characteristics (e.g.
exact timing of orgasm duration, erectile response).
In contrast to previous data using punctual blood
sampling [8, 34], sexual arousal in the current paradigm
induced elevations in plasma testosterone concentrations
that did not reach statistical signi®cance. However, basal
testosterone levels were elevated throughout the session
following abstinence when compared to values obtained
prior to abstinence. Enhanced testosterone may have
been a physiological response to re-initiate sexual
activity throughout the abstinence period, since
increasing testosterone concentrations have been shown
to stimulate the initiation of coital and other partnered
sexual activity [19, 20]. However, this appears unlikely
because baseline testosterone levels at the beginning of
the video sequence were similar before and after absti-
nence.
On the other hand, the increased testosterone
concentrations may have resulted from enhanced sensi-
tivity to anticipatory cues, since testosterone secretion
increases in anticipation of sexual interaction [18]. Thus,
the increase in testosterone following abstinence may
have resulted from increased anticipation of the erotic
®lm. Although initial basal testosterone values (10 min
timepoint) were not altered by abstinence, the dierence
between conditions that appeared after the start of the
session (20±60 min) support this position.
Such anticipatory or preparatory sex hormone re-
sponses are suggested by several other studies [3, 25, 31]
and seem to re¯ect more general appetitive responses in
the expectation of the potentially rewarding conse-
quences of sexual activity. As appetitive responses are
behaviors that represent a central motivational state for
contact with a goal object [2], increased testosterone
concentrations may represent an enhancement of the
aective properties of the goal object by sexual absti-
nence. Furthermore, a close interaction exists between
steroid hormones and the brain systems involved in
reward. Speci®cally, acute increases in testosterone have
possible neural rewarding qualities [2]; this eect is
potentially mediated by dopaminergic systems [14]. With
regard to our current results, one can speculate that
sexual abstinence has a twofold eect on this interaction
pattern: It may enhance the anticipated rewarding
properties of re-initiated sexual activity and it may lower
the threshold at which testosterone produces rewarding
eects. Both factors may interact to trigger the elevated
testosterone levels observed following abstinence.
The enhanced subjective qualities of sexual arousal
and orgasm intensity following sexual abstinence may
also be explained by increased testosterone concentra-
tions. Indeed, elevated levels of testosterone in men are
known to enhance nocturnal erections [12], probably by
acting on peripheral neurons that control copulatory
re¯exes [23]. Additionally, some evidence suggests that
testosterone stimulates the erectile response to experi-
mentally-induced sexual arousal; however, this position
remains equivocal [7]. Nevertheless, increased testoster-
one elevates feelings of sexual arousal and libido [1, 6],
and increases both orgasmic frequency [27] and coital
initiation [20]. Thus, our data suggest that testosterone
may have in¯uenced the subjective assessment of sexual
arousal either by directly modifying genital reactions, or
alternatively, by manipulating the CNS structures that
regulate sexual motivation and arousal.
Summarizing, the current study demonstrated that
masturbation-induced orgasm produces pronounced
elevated cardiovascular responses and plasma concen-
trations of catecholamines and prolactin. Although
these responses were unaltered by acute abstinence from
sexual activity, abstinence increased subjective sexual
arousal and the quality of the orgasm, as well as basal
testosterone concentrations. Thus, although acute
abstinence enhances subjective sexual arousal it has
little impact on the acute neuroendocrine response to
orgasm.
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