Effect of transient scrotal hyperthermia on spermatogenesis

Plain English Summary

Background and study aims
The testes of most animals, including humans, are in the scrotum outside the main body cavity and are thus 2–8°C below the core body temperature. Scrotal hyperthermia (elevated temperature) could disrupt sperm production and lead to a decreased sperm count. However, most studies are based on animal models, and we still don’t know the relationship between scrotal heat stress and the degree of damage to sperm production. The mechanism of disruption of sperm production is also unclear. Therefore, this study aims to investigate the effect of scrotal hyperthermia on human sperm production and to understand the related mechanism.

Who can participate?
Healthy men aged 22–50 who are married, have fathered at least one child, and do not plan to father another child.

What does the study involve?
Participants are randomly allocated into one of the two groups. All of the participants undergo testicular warming at 43°C in a water bath 10 times, for 30 minutes each time. In brief, the lower half of the body of each participant is soaked in a bathtub in which the water is regulated to be 43°C. For participants in Group 1, this is carried out once a day for 10 consecutive days while for subjects in Group 2, it was once every 3 days, 10 times. The treatment phase is followed by a recovery phase of 16 weeks. Blood samples are collected before and every 3 weeks after the water bath treatment, a total of 6 times. Semen samples are collected twice before the water bath treatment and every 2 weeks after, for a total of 10 times.

What are the possible benefits and risks of participating?
The main benefit for participants in this study is the evaluation of their semen quality and reproductive hormone levels, which are good markers for their health status. The results of this study will improve our understanding of the risks of high scrotal temperature. There are no risks for participants in this study.

Where is the study run from?
Huazhong University of Science and Technology (China)

When is the study starting and how long is it expected to run for?
May 2013 to August 2015

Who is funding the study?
Ministry of Science and Technology of the People's Republic of China

Who is the main contact?
Prof Changhong Zhu
rm3816205@163.com

Study website

Type

Scientific

Contact name

Prof Changhong Zhu

ORCID ID

Contact details

No.13
Hangkong Road
Wuhan
430030
China
+86 (0)27 8369 2651
rm3816205@163.com

EudraCT/CTIS number

IRAS number

ClinicalTrials.gov number

Protocol/serial number

N/A

Scientific title

Effect of transient scrotal hyperthermia on spermatogenesis

Acronym

Study hypothesis

Previous studies have shown that cryptorchidism and varicocele can seriously affect spermatogenesis, mainly due to the elevated temperature of the scrotum. However, those studies were mainly retrospective. The heat stress intensity and exposure time lacked accurate quantification, and the relationship between heat exposure frequency and the degree of spermatogenesis damage was not explored.

Hypothesis: Transient scrotal hyperthermia could reversibly affect spermatogenesis

Ethics approval(s)

Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology, 28/11/2012, No. 20130311

Study design

Single-center interventional randomised controlled trial

Primary study design

Interventional

Secondary study design

Randomised controlled trial

Study setting(s)

Other

Study type

Other

Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet

Condition

Spermatogenesis

Intervention

Subjects were initially randomized into one of the two groups, each group consisting of 10 volunteers. All of the subjects underwent testicular warming at 43°C in a water bath 10 times, for 30 min each time. In brief, the lower half body of each subject was soaked in the bathtub in which the water was regulated to be 43°C. To maintain the water temperature constant, we continuously added the adjusted hot water (43°C) into the bathtub, and we also drained the water from the bathtub by the same flow rate. For subjects in Group 1, this was carried out once a day for 10 consecutive days while for subjects in Group 2, it was once every 3 days, 10 times. The treatment phase was followed by a recovery phase of 16 weeks.

Intervention type

Other

Primary outcome measure

Semen samples were collected twice before treatment and at week 2, 4, 6, 8, 10, 12, 14 and 16 after treatment. The samples were obtained from each subject by masturbation after between 3 and 7 days of sexual abstinence.

1. Sperm concentration, sperm motility and total sperm count were observed under a microscope.
2. Total acrosin activity was measured using a commercially available kit (HuaKang, Shenzhen, China).
3. Seminal plasma biochemical markers including semen plasma fructose, zinc and neutral alpha glucosidase, were all tested by using enzymic and spectrophotometric methods.
4. Semen plasma oxidative stress was evaluated by the markers of superoxide dismutase (SOD), catalase (CAT) activity and malondialdehyde (MDA), these markers were all tested by using a spectrophotometric method.

Venous blood samples were collected before treatment and at week 3, 6, 9, 12, 15 after treatment, 4 ml for each time. Blood samples were used for reproductive hormone assays, including follicle stimulating hormone (FSH), luteinizing hormone (LH), sex hormone binding globulin (SHBG), estradiol (E2), testosterone and free testosterone. All these hormones were tested using a chemiluminescent immunoassay method on the automated UniCel DxI 800 analyzer.

Secondary outcome measures

Semen samples were collected twice before treatment and at week 2, 4, 6, 8, 10, 12, 14 and 16 after treatment. The samples were obtained from each subject by masturbation after between 3 and 7 days of sexual abstinence.
1. Sperm DNA integrity was detected using flow cytometry
2. Sperm apoptosis was evaluated using mitochondrial membrane potential commercial assay kit and TdT-mediated dUTP nick-end labeling (TUNEL) assay kit
3. Sperm protein levels were analyzed by using a western blotting method.

Overall study start date

01/05/2013

Overall study end date

30/08/2015

Reason abandoned (if study stopped)

Participant inclusion criteria

1. Male
2. 22–50 years old
3. Married and having fathered at least one child
4. No plan to father another child
5. Good health without hypertension or trauma

Participant type(s)

Healthy volunteer

Age group

Adult

Sex

Male

Target number of participants

20

Total final enrolment

20

Participant exclusion criteria

1. Not married or have no children
2. Plan to have another child
3. Cryptorchidism or varicocele
4. Severe heart, brain or renal disease
5. Could not commit to finishing the experiment

Recruitment start date

01/05/2013

Recruitment end date

20/07/2013

Countries of recruitment

China

Study participating centre

Family Planning Research Institute
Tongji Medical College
Huazhong University of Science and Technology
No.13 Hangkong Road
Wuhan
430030
China

Study participating centre

Reproductive Medicine Center
Tongji Medical College
Huazhong University of Science and Technology
No.13, Hangkong Road
Wuhan
430030
China

Organisation

Chinese Academy of Sciences (China)

Sponsor details

Institute of Zoology
1 Beichen West Road
Chaoyang District
Beijing
100101
China
+86 (0)10 6480 7098
liuyx@ioz.ac.cn

Sponsor type

Research organisation

Website

http://www.ioz.ac.cn/

ROR

https://ror.org/034t30j35

Funder type

Government

Funder name

Ministry of Science and Technology of the People's Republic of China

Alternative name(s)

Chinese Ministry of Science and Technology, MOST

Funding Body Type

government organisation

Funding Body Subtype

National government

Location

China

Publication and dissemination plan

To be confirmed at a later date

Intention to publish date

Individual participant data (IPD) sharing plan

IPD sharing plan summary

Available on request

Study outputs