Vol. 26, No. 2, February 1975 Printed in U.S A.
FERTILITY AND STERILITY Copyright c 1975 The American Fertility Society
STIMULATION OF EJACULATED HUMAN SPERMATOZOA BY CAFFEINE* CY SCHOENFELD, PH.D.,t RICHARD D.AMELAR, M.D.,
AND
LAWRENCE DUBIN, M.D.
Fertility Laboratory, Inc, and New York University School of Medicine, New York, New York 10016
Preliminary reports have shown that caffeine (1, 3, 7-trimethyl-2, 6-dioxypurine) stimulates motility 1•3 and forward progression3 of ejaculated human spermatozoa. Stimulation of the kinetic activity and respiration of bovine epididymal and ejaculated spermatozoa have also been reported.4·5 Garbers et al 6 suggested that the motility of bovine spermatozoa is at least partially controlled by cyclic AMP (adenosine 3' :5' cyclic monophosphate) and/or by cyclic GMP (guanosine 3' :5' cyclic monophosphate). Although human spermatozoan metabolism is predominantly a glycolytic process, a significant amount of oxidative metabolism also occurs. 7 This metabolism is greatly affected by cyclic AMP as well as by other substances. 8 The role of cyclic nucleotides in mammalian spermatozoa has been extensively reviewed.9 The present study was designed to evaluate the effects of caffeine on spermatozoa of low and normal motility in order to verify the preliminary findings.
sion. For statistical analysis, the specimens were given grades of 1.0, 1.5, and so on, instead of 1, 1 +, and so on, normally used in grading motility. 10 Specimens exceeding 2.0 ml were studied within 1.5 hours of ejaculation. Specimens were divided into four aliquots of 0.5 ml each for use as paired controls and paired experimental samples. To each of the control samples, 0.1 ml of a modified Ringer's buffer solution (120 mM NaCl, 5 mM KCl, 10 mM KH2 P0 4 , 5 mM MgS0 4 • H 2 0, 1 mM TrisHCl, pH 7 .2) was added. To each of the experimental samples, 0.1 ml of this buffer containing 36 mM of caffeine (final concentration, 6 mM caffeine) were added. All samples were incubated at 37°C and 0.05 ml aliquots were removed and examined 0, 1, 2, 3, 4, and 5 hours later. The specimens were divided into four groups based on initial percent motility of spermatozoa: group 1, ten specimens with 10% and 25 with 20% initial motilities; group 2, 23 specimens with 30% and 32 with 40%; group 3, 25 with 60%, six with MATERIALS AND METHODS 70%, and four with 80%; and, group 4, The percentage and type of motile cells three with no motility. All percentages were estimated in 128 human semen speci- are expressed as the mean ± SE. mens. Motility was graded from 0 to 4.0 based upon the type of forward progresRESULTS
Received April 9, 1974. *Presented at the 30th Annual Meeting of the American Fertility Society, April 1974, Hollywood, Florida. tReprint requests: Dr. Schoenfeld, Fertility Laboratory, Inc, 137 East 36th Street, New York, New York 10016.
Caffeine (6 mM) markedly stimulated and maintained motility of ejaculated human spermatozoa in groups 1, 2, and 3 (Fig. 1). Group 1, which had an initial motility of 10% to 20% (mean ± SE, 16.8% ± 0.54%) showed an increase in
158
159
CAFFEINE STIMULATION OF SPERMATOZOA
Vol. 26, No.2
10- 20 Percent Initial Motility (3S specimens)
30·40 Peo:ent lrit;al -Hty (55_......,
60-BO Pe.ced lritial (35
Momay
-;-~
•
-- _. Canhol
o---o
Caffe;ne
lr - - -4 Cant«>l
t:.:----1:J.
Caffeine
80
- -·-- - -... -------
--------------------- -------- .. 0
HOURS
FIG. 1. Effect of 6 mM caffeine on the motility of ejaculated human
spermatozoa.
mean motility to 29.9% ± 1.02% after one hour of caffeine exposure, compared with 17.0% ± 0.61% forcontrols. At four hours, this group showed more appreciable differences; the caffeine-treated spermatozoa had a motility of30.8% ± 1.14%, whereas the controls had 10.9% ± 0.62%. The caffeine-treated spermatozoa maintained this increase for between four and five hours; a drop was first noted at five hours. Differences between the control and caffeine-treated groups between one and five hours were statistically significant (P
FERTILITY AND STERILITY Copyright c 1975 The American Fertility Society
STIMULATION OF EJACULATED HUMAN SPERMATOZOA BY CAFFEINE* CY SCHOENFELD, PH.D.,t RICHARD D.AMELAR, M.D.,
AND
LAWRENCE DUBIN, M.D.
Fertility Laboratory, Inc, and New York University School of Medicine, New York, New York 10016
Preliminary reports have shown that caffeine (1, 3, 7-trimethyl-2, 6-dioxypurine) stimulates motility 1•3 and forward progression3 of ejaculated human spermatozoa. Stimulation of the kinetic activity and respiration of bovine epididymal and ejaculated spermatozoa have also been reported.4·5 Garbers et al 6 suggested that the motility of bovine spermatozoa is at least partially controlled by cyclic AMP (adenosine 3' :5' cyclic monophosphate) and/or by cyclic GMP (guanosine 3' :5' cyclic monophosphate). Although human spermatozoan metabolism is predominantly a glycolytic process, a significant amount of oxidative metabolism also occurs. 7 This metabolism is greatly affected by cyclic AMP as well as by other substances. 8 The role of cyclic nucleotides in mammalian spermatozoa has been extensively reviewed.9 The present study was designed to evaluate the effects of caffeine on spermatozoa of low and normal motility in order to verify the preliminary findings.
sion. For statistical analysis, the specimens were given grades of 1.0, 1.5, and so on, instead of 1, 1 +, and so on, normally used in grading motility. 10 Specimens exceeding 2.0 ml were studied within 1.5 hours of ejaculation. Specimens were divided into four aliquots of 0.5 ml each for use as paired controls and paired experimental samples. To each of the control samples, 0.1 ml of a modified Ringer's buffer solution (120 mM NaCl, 5 mM KCl, 10 mM KH2 P0 4 , 5 mM MgS0 4 • H 2 0, 1 mM TrisHCl, pH 7 .2) was added. To each of the experimental samples, 0.1 ml of this buffer containing 36 mM of caffeine (final concentration, 6 mM caffeine) were added. All samples were incubated at 37°C and 0.05 ml aliquots were removed and examined 0, 1, 2, 3, 4, and 5 hours later. The specimens were divided into four groups based on initial percent motility of spermatozoa: group 1, ten specimens with 10% and 25 with 20% initial motilities; group 2, 23 specimens with 30% and 32 with 40%; group 3, 25 with 60%, six with MATERIALS AND METHODS 70%, and four with 80%; and, group 4, The percentage and type of motile cells three with no motility. All percentages were estimated in 128 human semen speci- are expressed as the mean ± SE. mens. Motility was graded from 0 to 4.0 based upon the type of forward progresRESULTS
Received April 9, 1974. *Presented at the 30th Annual Meeting of the American Fertility Society, April 1974, Hollywood, Florida. tReprint requests: Dr. Schoenfeld, Fertility Laboratory, Inc, 137 East 36th Street, New York, New York 10016.
Caffeine (6 mM) markedly stimulated and maintained motility of ejaculated human spermatozoa in groups 1, 2, and 3 (Fig. 1). Group 1, which had an initial motility of 10% to 20% (mean ± SE, 16.8% ± 0.54%) showed an increase in
158
159
CAFFEINE STIMULATION OF SPERMATOZOA
Vol. 26, No.2
10- 20 Percent Initial Motility (3S specimens)
30·40 Peo:ent lrit;al -Hty (55_......,
60-BO Pe.ced lritial (35
Momay
-;-~
•
-- _. Canhol
o---o
Caffe;ne
lr - - -4 Cant«>l
t:.:----1:J.
Caffeine
80
- -·-- - -... -------
--------------------- -------- .. 0
HOURS
FIG. 1. Effect of 6 mM caffeine on the motility of ejaculated human
spermatozoa.
mean motility to 29.9% ± 1.02% after one hour of caffeine exposure, compared with 17.0% ± 0.61% forcontrols. At four hours, this group showed more appreciable differences; the caffeine-treated spermatozoa had a motility of30.8% ± 1.14%, whereas the controls had 10.9% ± 0.62%. The caffeine-treated spermatozoa maintained this increase for between four and five hours; a drop was first noted at five hours. Differences between the control and caffeine-treated groups between one and five hours were statistically significant (P
