Ethical statement
All animal trials were executed according to local and worldwide procedures. The nearby way is the Wet op de dierproeven (article 9) of Dutch law (international) and an associated rule planned via the Bureau of Animal Research Licensing, Local University as detailed in our earlier papers (Ali et al. 2020; Hussain et al. 2020; Ali et al. 2020; Ara et al. 2020; Ali et al. 2020; Khan et al. 2019; Ali et al. 2019; Mumtaz et al. 2019; Mughal et al. 2019; Dar et al. 2019). The rearing and use of mice were carried out using NIH Publication “Guide for the Care and Use of Laboratory Animals” (NRC 2004) and with the approval vide No. D/681/UZ dated 04-04-2019 by the local bioethical committee of the University on animal experimentation.
Chemicals
Diethyl Phthalate 99.5% purity, MW: 222.24 were purchased by Sigma Aldrich. Honey used in this research was multiflora honey collected in April from Apis mellifera colonies taken from Honeybee Research Farm, University of the Punjab, Lahore, Pakistan. Corn oil with 99.9% purity was purchased from the Akbari market, Lahore. Hormones Diagnostic Kits were BioVision Company, distributed by Lab Science, Pakistan. Ethanol, hematoxylin, eosin, hydrochloric acid, ferric chloride and ferrous sulphate were obtained from Merck & Co., Inc. TPTZ (2,4,6-Tris(2-pyridyl)-s-triazine) was acquired from Sigma-Aldrich Company. All chemicals used in the present research were of analytical grade.
Animals Rearing
Swiss Webster strain of albino mice Mus musculus was used in the experiment. Mice were raised employing steel cages with well-managed conditions of 12 hours’ light/dark cycle at 26±2 °C and 45-55% relative humidity in the animal house of the Institute of Zoology, University of the Punjab, Lahore, Pakistan. Mice were fed with commercially available feed (national feed No. 14 by National Feeds industries, Lahore, Pakistan) pellets and water ad libitum.
Experimental Design
Four-week-old 50 male mice with body weight (B.W.) 13±2 g were randomly classified into five groups (n=10). Group 1: control (C) provided 0.1 ml distilled water; group 2: vehicle control (VC) administered 0.1 ml corn oil; group 3: DEP treated with 3 mg/g B.W. DEP, dissolved in corn oil in such a way that 0.1 ml contained required concentrations of DEP; group 4: DEP (3 mg/g B.W) and honey (0.2 mg/g); Group 5: honey control (HC) exposed to honey (0.2 mg/g B.W). Treatments were given through oral gavage for 54 days daily, once a day. Before treatment, antioxidant potential and total phenolic content (TPC) were also assessed separately for raw honey used in this study.
General observations
Behavioral and other physical changes in mice of all groups were noted and recorded twice a day regularly. The body weight of each animal in each group was measured on weekly basis and dose concentrations were adjusted considering their weights accordingly.
Samples recovery
After 54 days, the animals were acclimatized for 6 days for self-restoration and were euthanized after isoflurane inhalation. Testes and epididymis were successfully recovered for morphometric, histopathologic, micrometric analyses, sperm count, and antioxidant capacity test (FRAP). The blood samples were collected by cardiac perfusion for hormonal assays under deep anesthesia.
Morphometric Analysis
Mice body weight and wet weight of the testes were measured with analytical balance (Ax120 SHIMADZU, JAPAN). Furthermore, the size (length/width) of testes was recorded using a digital Vernier caliper.
Histopathology
Testicular tissues were fixed in Bouin’s fixative for 40 hrs at room temperature (33°C), dehydrated with graded ethanol, cleared with xylene and embedded in paraffin blocks. The thick sections (5µm) were prepared by rotary microtome and stained with eosin and hematoxylin following established protocols (Bancroft and Layton, 2013). The sections were observed and digital photographs were captured under a camera-fitted microscope to highlight histopathological defects and micrometric data.
Micrometry
For micrometric measurements, from photomicrographs taken at 40X, twenty nearly round randomly chosen seminiferous tubules were traced. Seminiferous tubule and lumen diameters were measured through bisecting lines drawn at the circumference of the tubule using ImageJ software at 400 magnifications (Montoto et al. 2012). The cross-sectional area of the seminiferous tubule (STA) was calculated following a geometric constant equation (Mustafa et al. 2019)
STA = πr2
Where r is the tubule radius.
The area of the tubular lumen (LA) was calculated by the equation:
LA = πLr2
Where Lr is the luminal radius.
The epithelium area (EA) was obtained by subtracting LA from STA. Results were expressed as square millimeters (mm2).
Smear preparations for sperm count and morphology
Testes with attached epididymis recovered in saline solution, give a midline incision, gently crushed on clean glass with a glass rod and curdy material used for the sperm count and sperm morphological analysis through the chamber counting method. The sperm with complete head and tail counted once in 4 big 1 mm2 quadrates under a light microscope (Kirkman-Brown et al., 2009).
Hormonal Analysis
Hormonal analysis for testosterone level and Luteinizing hormone were assessed in the mice blood samples by kits (BioVision). Hormones were assayed following kit instructions in triplicates.
Antioxidant Capacity Test
Tissue homogenate preparation
Testis tissues were preserved in 1.15% ice-cold KCl at -800C for few hours. Fresh testes were weighed and homogenates were prepared using a glass homogenizer with ice-cold 1.15% KCl (10% w/v) to record the antioxidant effect of honey within tissues. Then homogenates were centrifuged at 15000 rpm for 10 min at 40C. The supernatants were collected for further processing (Katalinica et al., 2005).
Ferric Reducing Antioxidant Power in mice tissues and honey
The antioxidant power in tissues and honey was measured following the ferric reducing antioxidant power (FRAP) assay (Katalinica et al., 2005). The antioxidants present in the supernatant were evaluated as a reducer of Fe+3 to Fe+2, which is chelated by 2,4,6-Tris(2-pyridyl)-s-triazine (TPTZ) to form the complex and evaluated using the maximal absorption at 593 nm. The results were presented in µM equivalent ascorbic acid/mg sample.
Total Phenolic Content (TPC)
Honey was assessed for the presence of phenolic contents following Valverde et al. (2015) protocol. Briefly, 1.0 mL of the diluted honey samples were transferred in separate tubes containing 5.0 mL of 1/10 dilution of Folin-Ciocalteu’s reagent in water. Then, 4 mL of a sodium carbonate solution (7.5% w/v) was added. The tubes were allowed to stand at room temperature for 60 min before absorbance at 765 nm was measured. The unit was expressed in a Gallic acid equivalent g/100 g sample.
Statistical analysis
Statistical analysis was carried out using SPSS software (IBM, version 21.0). The data were expressed in terms of mean ± SEM and mean differences between all experimental groups were measured by one-way ANOVA followed by Post hoc Tukey and Duncan’s multiple range tests. All the tabulated data presented as mean ± standard error of means and value p < 0.05 was considered significant.