Unravel the Role of Oxidative Stress on Fertility Potential of Type II Diabetes Mellitus in Men in South India

Research Article

Austin J Reprod Med Infertil. 2016; 3(2): 1043.

Unravel the Role of Oxidative Stress on Fertility Potential of Type II Diabetes Mellitus in Men in South India

Malini SS*

Department of Studies in Zoology, University of Mysore, India

*Corresponding author: Malini SS, Department of Studies in zoology, University of Mysore, Manasagangothri, Mysore-06, India

Received: October 27, 2016; Accepted: December 12, 2016; Published: December 15, 2016


Objective: Study was undertaken to disentangle the role of oxidative stress in Type 2 diabetes mellitus and its effect on fertility potential of the individuals.

Materials and Methods: The study was conducted at Molecular reproductive and human genetics lab, University of Mysore, Mysore. Confirmed 200 Type 2 DM male patients, 100 infertile and 100 control males with the age group between 25-45 years were evaluated through semen analysis and sperm function test according to WHO guidelines. Oxidative stress was studied by estimating reactive oxygen species and enzymatic antioxidants such as superoxide dismutase and catalase along with total antioxidant capacity, using seminal plasma and pellet. Estimation of hormones was carried out by ELISA.

Results: Spermiogram shows noticeable significant differences in the count, pH, motility, morphology and vitality in infertile individuals but between diabetic and non-diabetic individuals only vitality showed significant difference. Functional potentiality of spermatozoa of such as plasma membrane permeability, nuclear decondensation and enzymatic activities of acrosomes of infertile conditions was below the normal levels of WHO guidelines. But between type II diabetic and healthy men except acrosome tests other two tests were significantly varied indicating the probability of subfertility/infertility. In addition, variation in insulin level was evident in type II diabetic men. Even though ROS level is significantly differ between type II diabetic and healthy men, but total antioxidant capacity was not altered could be due to increased scavenging activity of SOD.

Conclusion: Reactive oxygen species in type II diabetic mellitus being reduced due to high scavenging activity of antioxidant enzyme SOD. SOD levels were more in compared to catalase and total antioxidant capacity. Varied semen parameters could be due to insulin variation in type II diabetic men.

Keywords: Diabetes mellitus; Oxidative stress; Antioxidants; Sub-fertility and infertility


Diabetes mellitus (DM) is a common, potentially devastating, treatable but incurable lifelong disease [1]. According to the diabetic atlas of the International Diabetic Federation, 366 million people were affected by diabetes worldwide in 2011, and diabetes prevalence is expected to 522 million by 2030 [2]. Diabetes has been associated with reproductive impairment in both men and women [3,4], and its impact on reproduction can be profound, as seen by diminution in fertility and increase in reproductive losses [5-8]. About 90% of diabetic male patients have disturbances in sexual function, including a decrease in libido, impotence and infertility [9]. Semen analyses reveal some decrease in sperm motility, density, abnormal morphology and generally increased semen plasma abnormalities in diabetic men. Interestingly, a contradicting paper has shown that, even when diabetic men present normal semen parameters, there is a higher level of damage to both nuclear and mitochondrial sperm DNA, when compared to what is found in healthy controls [10].

Un controlled hyperglycemia is an important risk factor for the development of micro and macro vascular disease in patients with type 2 diabetes, has been shown in several observational studies. There was a reduction in the risk of complications in the intensive compared with standard glycemic control group [11,12]. A phenomenal work from Queen’s University has revealed that high level of blood sugar may affect sperm quality and therefore decreases male fertility potentials [10]. Even though the degree of correlation between glucose level and testicular damage a established factor [13], several reports indicate the production of oxygen radicals from glycated proteins under physiological conditions results type II diabetic mellitus T2DM [14,15]. Free radicals are known to stimulate advanced glycation end products (AGEs) production by autoxidation of sugars [16], hence enhances Oxidative Stress (OS). OS has been linked to diabetic complications and it has also been reported to be associated with severe changes in the structure and function of the testes, 2 weeks after the onset of diabetes [17,18]. OS is the excess formation and/or insufficient removal of highly reactive molecules such as Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) [19,20].

Reactive molecules such as superoxide (O2 -), Nitric Oxide (NO) and (peroxynitrite) ONOO- are the most widely studied species, and they play important roles in diabetic cardiovascular complications [21,22] Reduced antioxidant levels, as a result of increased free radical production in experimental diabetes, have been reported by Grankvist, et al. and Kanter, et al. [23,24]. As such the prevalence of type 1 diabetes mellitus is rare and research pertaining to its influence on fertility status in males is sparse. Hence, the main objectives of this study are to compare oxidative stress in control subjects, infertile and T2DM individuals to know whether oxidative stress has any role on semen profile and functional potentiality of spermatozoa among T2DM individuals by estimating reactive oxygen species and enzymatic antioxidants as well as total antioxidant capacity.

Materials and Methods

A total of 200 T2DM, 100 infertile individuals and 100 control male subjects aged between 25-45 years were recruited irrespective of caste and religion from different diabetic centers and clinics in and around Mysore, India. After excluding T2DM associated metabolic disorders such as obesity, thyroid, hypertension, testosterone replacement therapy within 6 months of randomization, hormonemodulating therapies or topical/systemic glucocorticoids within 3 months of randomization, or insulin therapy; a history of recurrent prostate infection, infertility along with smoking, alcohol and drug abuse, long term medication etc, 152 cases and 50 control subjects and 75 infertile cases were used for all the analysis. The study was approved by the institutional ethical clearance committee of University of Mysore and concerned hospitals (IHEC-UOM No.12/Res/2009-10). Informed written consent letter was taken from the participants and subjects were interviewed to collect information about family, medical, reproductive histories which includes the duration of active married life, premature ejaculation and psychological status of the subjects and life style factors.

Semen collection and preservation

The semen samples were collected after 3-5 days of ejaculatory abstinence according to WHO guidelines (2010). Physical examination such as volume, liquefaction time, colour, pH and viscosity were recorded after liquefaction. Microscopic examinations were carried out to record the count, density, motility and morphology of the spermatozoa. Single blinded semen analysis was carried out for both control and diabetic individuals and infertile individuals according to WHO guidelines.

Sperm function tests

Functional potentiality of spermatozoa was evaluated by conducting sperm function tests for both T2DM individuals and control subject after the completion of microscopic and macroscopic analysis of semen and spermatozoa.

Nuclear Chromatin Decondensation Test (NCD)

This test was carried out to check the ability of decondensation of nuclear chromatin in vitro in spermatozoa. Semen sample was centrifuged to separate plasma. The pellets were washed with 0.05M borate buffer. One volume of sample was mixed with nine volumes of EDTA-SDS mixture and incubated at 37° C for 60 min. An equal volume of glutaraldehyde borate buffer was added. A drop of this mixture was transferred on to clean glass slide and covered with cover slip and observed under microscope in 400X magnification. The number of condensed and decondensed heads was counted. If more than70% of spermatozoa shows decondensed nuclear chromatin then it was considered as normal.

Hypo-Osmotic Swelling Test (HOS)

Integrity of plasma membrane was performed using this test. Hypo-osmotic solution was prepared using fructose and sodium citrate in equal proportion. One ml of this solution was incubated at 37° C for 10 min and 100μl of semen sample was mixed. It was incubated at 37°C for 30 min. This mixture was dropped on precleaned glass slide, covered with cover slip and observed under microscope in 400X magnification. Percentage of coiled (curled) tail was recorded. If more than 60% of spermatozoa, shows coiled tail then it was considered as normal.

Acrosomal Intactness Test (AIT)

Quality of the acrosomal enzymes were analyzed using this test. Gelatin coated slides were prepared by spreading warm aqueous solution of gelatin on to a clean glass slide and kept horizontally at 40°C for 24 hours. These coated slides were immersed in PBSglutaraldehyde solution for 2 minutes and washed using distilled water and stored at 40° C. Semen was mixed with PBS- D-glucose in the ratio of 1:5 and incubated at 37° C for 10 min. Gelatin coated slides were allowed to come to room temperature. A drop of diluted semen samples was smeared over gelatin slide. This slide was placed on to a petri dish containing a moistened filter paper and incubated for two hours at 37°C. The slides were examined under phase contrast microscope in 400X magnification. The percentage spermatozoa with halos surrounding the head were recorded. Values more than 50% was considered as normal.

Chemiluminescence’s assay for reactive oxygen species (ROS) measurement

Liquefied semen was collected from T2DM individuals and control subjects and centrifuged at 300x g for 7 minutes, and the seminal plasma was separated. The pellet was washed with Phosphate- Buffered Saline (PBS) and resuspended in the same washing media at a concentration of 20 x 106 sperm/ml. Four hundred microliter aliquot of the resulting suspensions was used to assess basal ROS levels. Ten microliter of luminol (5-amino-2,3-dihydro-1,4-phthalazinedione), prepared as 5mM stock in dimethyl sulfoxide (DMSO) was added to the mixture and serve as a probe. A negative control was prepared by adding 10μl of 5mM luminol to 400μl of PBS. Luminol is an extremely sensitive oxidizable substrate that has the capacity to react with a variety of ROS at neutral pH. The reaction of luminol with ROS results in production of a light signal that is read in luminometer as arbitrary light units.

Assay of Catalase in human seminal plasma

In the UV range, H2O2 shows a continual increase in absorption with decreasing wavelength. The decomposition of H2O2 can be followed directly by the decrease in absorbance at 240nm. The difference in absorbance per unit time is a measure of the Catalase activity. The substrate was diluted with phosphate buffer and its initial absorbance was recorded. 10μl of seminal plasma was added and the decrease in OD was noted at 240nm. The Catalase activity is expressed as k/ml and is calculated using the following relation: The Catalase activity is expressed as k/ml and is calculated using formula k/ml = ka, k = (2.3/t)*logA1/A2 where, t= time interval, A1 = Initial absorbance, A2 = final absorbance, a = dilution factor.

Superoxide Dismutase (SOD)

SOD levels for the study subjects and controls were estimated by Das, et al. (2000) method to infer the concentration of SOD being consumed for lipid peroxidation taking place in the cells of the subjects to reduce the oxidative stress. A reaction mixture was prepared using respective volumes of phosphate buffer, a Methionine, Triton X, HAC (Hydroxylamine Hydrochloride) and EDTA (Ethylenediamine Tetra Acetic acid). 139μl of the reaction mixture was added to 10μl of sample and incubated for 5 min at room temperature. Simultaneously a blank was also run which constituted distilled water instead of sample. 8μl of phosphate buffer and riboflavin each was then added to the blank and samples respectively. All these were incubated at room temperature for 10min and then 100μl of Griess reagent was added to them. OD was observed at 543nm. In order to express the SOD level protein levels of the respective subjects are required which is estimated by Lowry’s method.

Total Antioxidant Capacity (TAC)

TAC levels of the subjects and controls were estimated by Phosphomolybdenum method to infer the total amount of antioxidants present in the subjects. To 100μl of serum 100μl of 5% TCA was added and left undisturbed for precipitation and ten centrifuged at 3000 rpm for 5min. to 100μl of this supernatant 1ml of TAC reagent was added and incubated for 90min at 90°C. OD was checked at 695nm. A blank was also run simultaneously.

Analysis of the hormones

The blood samples were collected from the T2DM individuals and control subjects and serum was separated by centrifuging at 3000 rpm for 5 minutes at room temperature. The obtained serum was used to estimate the levels of FSH, LH, testosterone, prolactin and insulin using CALBIOTECH ELISA kit. The readings were taken under Thermo-fisher multimode microtiter plate reader.

Statistical analysis

The obtained data was expressed in mean and standard error. Independent- samples‘t’-test was used to find out whether the significant difference exist between case and control subjects using statistical program SPSS (version 14.0). P value less than 0.05 were considered as significant.


Comparison of semen parameters between T2DM, and control subjects was statistically depicted in table 1. In the present investigation vitality (the percentage of living, healthy sperm in the semen) showed significant difference between control and diabetic group whereas other semen parameters were not affected. This result is not consistent with previous findings. Hence hyperglycaemic condition and wired management of insulin level has strong impact on vitality which is important for spermatozoa. The functional potential of the spermatozoa through NCD and HOS tests scores significantly different in T2DM and control group indicating failure in the decondensation of nuclear chromatin seems to be a vital factor for healthy spermatozoa. Similarly permeability of plasma membrane also highly compromised could be due to hyperglycemic condition in T2DM. But AIT showed no variation indicating acrosomal enzymes were not affected (Table 1).