Intratesticular injection of a zinc-based solution for contraception of domestic cats: A randomized clinical trial of efficacy and safety

Effects of intratesticular injection of hypertonic mannitol and saline on the quality of donkey sperm, indicators of oxidative stress and testicular tissue pathology

OBJECTIVES

The aim of the present study was to examine donkey sperm quality after intratesticular injection of hypertonic mannitol (HM) and saline (HS).

METHODS

Randomly assigned to five treatment groups were 15 adult male donkeys: (1) Control group (no treatment), (2) Surgery group (surgical castration for testosterone control), (3) NS group (normal saline intratesticular injection), (4) HS group (hypertonic saline), and (5) HM group. We injected 20 mL per testicle. We took 5 mL blood from all donkeys before injection. Castration was performed under general anesthesia 60 days later. Samples included blood and testicular tissue. Total motility (TM), progressive motility (PM), movementy features, DNA damage, morphology, viability, and plasma membrane functionality were evaluated. Hormone analyses, histomorphometric studies and oxidative stress indices including total antioxidant capacity (TAC), glutathione peroxidase (GPx), glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), and NADP+/NADPH were evaluated. Apoptosis, pyroptosis-related Bax, Caspase-1, GSDMD, and Bcl-2 expression were also assessed.

RESULTS

In HS and HM groups, testosterone, epididymal sperm count, motility, viability, and plasma membrane functionality dropped while sperm DNA damage increased. HS and HM groups had significantly lower histomorphometric parameters, TAC, GPx, SOD, GSH, and Bcl-2 gene expression. MDA, NADP+/NADPH, Bax, Caspase-1, and GSDMD gene expression were substantially higher in the HS and HM groups than in the control group.

CONCLUSIONS

Toxic effects of hypertonic saline and mannitol on reproductive parameters were seen following, hence, they might be considered as a good chemical sterilizing treatment in donkeys.

Evaluation of chemical castration using intra-testicular injection of zinc gluconate into the testis of the male donkey versus surgical castration: antimullerian hormone as an endpoint marker

BACKGROUND

Chemical castration of male animals is an alternative to surgical castration for inducing azoospermia, consequent sterility. Intra-testicular injection of zinc gluconate has been used for chemical castration in several animal species. However, its application to equine species, such as donkeys, has yet to be reported. This study aimed to evaluate the use of zinc gluconate for the chemical castration of male donkeys and to compare its effectiveness relative to routine surgical castration. For this purpose, investigations of serum testosterone and anti-Müllerian hormone levels, testicular ultrasonographic echogenicity, and histopathological findings were performed.

METHODS

Fourteen clinically healthy adult male donkeys were randomly and equally divided into two groups. The donkeys in group I (n = 7) underwent surgical castration. The donkeys in group II (n = 7) received intra-testicular zinc gluconate injections. The donkeys were kept under close clinical observation for 60 days. Abnormalities in donkey behavior and gross alterations in the external genitalia were recorded daily. Serum testosterone and anti-Müllerian hormone (AMH) levels were measured 15 days before the start of the treatment and 15, 30, 45, and 60 days after treatment. The testicles of group II donkeys were evaluated ultrasonographically. At the end of the study, the testes were removed and histologically examined.

RESULTS

Serum testosterone levels significantly declined compared to pre-castration levels in surgically castrated donkeys (group I), but donkeys exposed to chemical castration (group II) showed a non-significant reduction in testosterone levels. Donkeys in the surgical group had considerably lower serum AMH levels. In contrast, there was a non-significant (p > 0.05) increase in AMH levels in the chemical group compared with the pre-sterilization level. In addition, ultrasonographic examination revealed that the testicular echo-density had changed, as observed by a few scattered hyperechoic regions throughout the entire testis parenchyma. The histopathological investigation confirmed the presence of necrosis of the spermatogenic epithelium, increased thickness of the basement membrane of the seminiferous tubules, marked interstitial fibrosis, and shrinkage of the seminiferous tubules. Furthermore, syncytial giant cells were present in the lumen of seminiferous tubules and were associated with Sertoli cell vacuolation. Donkeys subjected to chemical castration (group II) had orchitis, as confirmed histopathologically.

CONCLUSION

Intra-testicular injection of zinc gluconate resulted in histopathological and ultrasonographic testicular changes in adult male donkeys, which may affect their reproductive potential. However, it did not significantly alter serum testosterone or AMH levels, indicating that it cannot be used as a substitute for surgical castration in male donkeys.

Reversible control of reproduction in tom cats: medical options for manipulating libido and fertility

BACKGROUND

There has been a growing interest in alternatives to surgery for controlling reproduction in tom cats, and the resultant medical options add to a practitioner's toolbox when handling these cases in clinical practice. It is important, however, that when suggesting these drugs, veterinarians have a good understanding of their mode of action, and their correct use and dosage.

CLINICAL RELEVANCE

Breeders increasingly wish to be able to switch on/off the reproductive ability of their tom cats in a controlled manner. In addition, in small animal medicine, there has been concern from some academics, and a growing number of pet cat owners, about potential long-term effects of surgical sterilisation. Further, for some cats surgical castration may not be possible due to health conditions that mean anaesthesia is unsafe. In all of these scenarios, medical alternatives to surgery can prove useful.

EQUIPMENT AND TECHNICAL SKILLS

No special equipment or technical skills are required. A good knowledge of the medical alternatives to surgical sterilisation for controlling reproduction in a tom, and making sure the patient is a suitable candidate, are, however, important for ensuring the cat's health during and after treatment and the owner's satisfaction.

AUDIENCE

This review is aimed principally (but not exclusively) at veterinary practitioners working with cat breeders who seek a temporary arrest in their tom cat's reproduction. It may also help practitioners with clients who would like an alternative to surgery or with cats where anaesthesia for surgical castration is not possible.

EVIDENCE BASE

Advances in reproductive feline medicine have resulted in improved knowledge of medical contraception. This review draws on scientific evidence-based papers that report on the mode of action, length of efficacy and potential side effects of different methods of medical contraception, as well as the authors' own clinical experience.

Feasibility evaluation of a Zn-Cu alloy for intrauterine devices: In vitro and in vivo studies

The comprehensively adopted copper-containing intrauterine devices (Cu-IUDs) present typical adverse effects such as bleeding and pain at the initial stage of post-implantation. The replacement of Cu material is demanded. Zinc and its alloys, the emerging biodegradable materials, exhibited contraceptive effects since 1969. In this work, we evaluated the feasibility of bulk Zn alloys as IUD active material. Using pure Cu and pure Zn as control groups, we investigated the contraceptive performance of Zn-0.5Cu and Zn-1Cu alloys via in vitro and in vivo tests. The results showed that the main corrosion product of Zn-Cu alloys is ZnO from both in vitro and in vivo studies. CaZn₂(PO₄)₂·2H₂O is formed atop after long-term immersion in simulated uterine fluid, whereas CaCO₃ is generally formed atop after implantation in the rat uterine environment. The cytocompatibility of the Zn-1Cu alloy was significantly higher than that of the pure Zn and pure Cu to the human endometrial epithelial cell lines. Furthermore, the in vivo results showed that the Zn-1Cu alloy presented much improved histocompatibility, least damage and the fastest recovery on endometrium structure in comparison to pure Zn, Zn-0.5Cu and pure Cu. The systematic and comparing studies suggest that Zn-1Cu alloy can be considered as a possible candidate for IUD with great biochemical and biocompatible properties as well as high contraceptive effectiveness. STATEMENT OF SIGNIFICANCE: The existing adverse effects with the intrinsic properties of copper materials for copper-containing intrauterine devices (Cu-IUD) are of concerns in their employment. Such as burst release of cupric ions (Cu²⁺) at the initial stage of the Cu-IUD. Zinc and its alloys which have been emerging as a potential biodegradable material exhibited contraceptive effects since 1969. In this study, Zn-1Cu alloys displayed significantly improved biocompatibility with human uterus cells and a decreased inflammatory response within the uterus. Therefore, high antifertility efficacy of the Zn-1Cu alloy was well maintained, while the adverse effects are significantly eased, suggesting that the Zn-1Cu alloy is promising for IUD.

Sperm impairing microbial factor: potential candidate for male contraception

BACKGROUND

Despite significant advances in contraceptive options for women, vasectomy and condoms are the only options available for male contraception. Due to this limitation, the burden of contraception resides on the shoulders of females only. Therefore, there is an urgent need to develop a safe, effective and reversible method of contraception for men. Amongst the alternative approaches, microbial derived products are gaining attention of the scientific world to combat unintended pregnancies. Earlier in our laboratory, sperm impairing microbial factor (Sperm immobilization factor) isolated from Staphylococcus aureus has shown excellent contraceptive efficacy in female mice. Keeping this in mind, the present study was carried out to exploit the sperm immobilization factor (SIF) as potential male contraceptive using vas deferens for administration in mouse model.

METHODS

SIF (10, 50, 100 or 200 μg) was inoculated in the lumen of right vas deferens whereas the left vas deferens served as control. The mice were sacrificed at Day 3, 7, 14, 21, 30, 45, 60 and 90 after inoculation and the results in terms of change in body weight, seminal parameters, Tissue somatic indices (TSI), haematological parameters, serum level of testosterone, lipid peroxidation and histology were studied. In order to ratify the SIF induced azoospermia SIF (200 μg) was administered with different doses viz. 100, 200, 300, 400 or 500 μg of SIF binding receptor extracted from mouse spermatozoa.

RESULTS

The weight profile studies of all the experimental groups showed no significant change in the initial and final body weight. In case of seminal parameters, the results revealed that right vas deferens treated with SIF showed azoospermia and with 200 μg of SIF it persisted up to 90 days. TSI of reproductive organs and non-reproductive organs showed no significant change in all the experimental groups. The haematological indices were found to be unaltered throughout the course of investigation however significant decrease in testosterone level was observed in the treated mice. The treatment also affected the oxidative status of the testis. Further, histological studies revealed hypospermatogenesis and late maturation arrest on treated side whereas the left side which served as control showed normal tissue histology. SIF induced azoospermia was ameliorated when administered with 400 μg of SIF binding receptor from mouse spermatozoa.

CONCLUSION

SIF, when administered via intra vas deferens route, could lead to complete azoospermia. Therefore, it could be considered as a potential male contraceptive.

Acute reproductive toxicology after intratesticular injection of silver nanoparticles (AgNPs) in Wistar rats

This study aimed to evaluate the effects of an intratesticular injection of silver nanoparticles (AgNPs) on reproductive parameters and health of rats, and to evaluate the AgNPs biodistribution in order to develop a nanotechnological contraceptive agent for male animals. Treated animals received 220 μL of AgNPs solution (0.46 µg-Ag/ml) in each testicle and were euthanized: seven, 14, 28, and 56 days after injection. A significant decrease (p < 0.05) in the percentage of motile sperm in D7 (8.8%) was observed, comparing to the control (73.3%), D14 (86.0%), D28 (68.2%), and D56 (90.0%) groups. D7 group also presented a decrease (p < 0.05) in the percentage of normal spermatozoa. Additionally, D7 group showed an increase (p < 0.05) in abnormal midpiece and sperm head morphology compared to the Control group. Seminiferous tubules presented all germline cell types and spermatozoa for all groups. However, D7 group did not present spermatozoa in the epididymis, whereas some spermatozoa and cellular debris were visible in D14 and D28 groups. All animals presented hematological parameters, creatinine, and alanine aminotransferase values within the normal limits for Wistar rats. The percentage of silver found in the liver was always higher than in the other organs analyzed. A pioneering mathematical model is proposed, from which the half-life time of silver in the liver (17 days), spleen (23 days), lungs (30 days), and kidneys (35 days) was extracted. In conclusion, some acute and severe toxic effects were observed in sperm cells following intratesticular injection of AgNPs, although these effects were reversible. No adverse effects to general animal health were observed.

Zinc injection as a novel castration method in beef bulls: effects on performance, behavior, and testosterone and haptoglobin concentration

Crossbred beef bulls (n = 180) were blocked by initial BW (337 ± 10.9 kg; six blocks) and assigned randomly to one of three treatments on day 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; received blood- restrictive rubber band placed around the dorsal aspect of the scrotum, 3) BUL; bulls with testicles remaining intact in a randomized complete block design (three treatment pens per block and 10 cattle per pen). A subset of 54 animals (n = 3 per pen) was fitted with accelerometers on day 0 to quantify behavior variables continuously for 28 d. Testis width and scrotal circumference, and serum haptoglobin (days 0, 1, 3, 5, 7, and 14) and testosterone concentrations (every 28 d until slaughter) were also determined for the subset. During the slaughter process, testes from INJ and BUL were collected to assess final testes weight and for histopathological evaluation. Data were analyzed using a mixed model (α = 0.05); pen served as the experimental unit for all dependent variables. Final BW was greater (P < 0.01) for INJ and BUL compared to BAN (672, 686, and 611 kg, respectively; SEM = 4.4). Overall ADG and G:F were greater (P ≤ 0.03) in INJ and BUL than BAN; whereas, DMI was similar between treatments for the study duration (P = 0.46). Histopathological evaluation (n = 13; INJ = 7; BUL = 6) indicated that INJ testes were degenerative and reproductively nonviable whereas BUL testes were normal. Serum testosterone concentrations on day 168 were similar (P = 0.14) between INJ and BUL whereas after day 14, BAN was nondetectable; however, initial serum testosterone concentrations were similarly low across treatments. Serum haptoglobin concentration was greater (P < 0.01) in INJ than BUL and BAN on days 1, 3, 5, and 7. Scrotal circumference (P = 0.08) and testis width (P = 0.07) on day 168 tended to be greater for BUL than INJ. Motion index (P ≤ 0.02) and step count (P = 0.04) was greater in BUL and INJ compared to BAN cattle during the 28 d monitoring period. No difference in standing time (P ≥ 0.85) or lying bouts (P = 0.35) occurred. Zinc injection resulted in sterilization but did not cause complete cessation of testicular function evidenced by testosterone concentrations more similar to BUL than BAN. This resulted in overall increased BW and G:F for INJ vs. BAN, yet the acute phase response was markedly greater directly after Zn injection. Collectively, Zn injection resulted in outcomes more similar to BUL than BAN, implying minimal efficacy of INJ as a castration method in older bulls arriving to the feedlot.

Carcass traits and consumer acceptability of striploin steaks from band-castrated, intratesticular zinc-injected, or sexually intact beef cattle

One hundred and eighty beef bulls (BW = 337 ± 10.9 kg) were blocked by BW (6 blocks) and assigned randomly to one of three treatments on day 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; received blood-restrictive rubber band placed upon the dorsal aspect of the scrotum, and 3) BUL; bulls with testicles remaining intact. Cattle were grouped by weight block in a randomized complete block design (three treatment pens/block and 10 cattle/pen) and harvested by block on three separate dates when blocks reached similar BW and visual subcutaneous fat thickness depth. Striploins were removed from the left carcass sides, vacuum packaged and aged for 14 d, and then frozen at −20 °C. Frozen striploins were sliced into 2.54-cm-thick steaks and remained frozen until analyses. Steaks (n = 3/animal) were used to assess consumer acceptability via consumer taste panel (n = 152 panelists), Warner-Bratzler shear force, percentage cook loss, and cooked color values. Data were analyzed using mixed model procedures; pen was the experimental unit for all dependent variables. Hot carcass weights and LM area were greater (P < 0.01) for the INJ and BUL treatments compared with BAN. Mean yield grade did not differ between treatments (P = 0.12), although BAN carcasses had smaller LM area (P < 0.01) than BUL or INJ carcasses. Percentage of USDA Choice or better carcasses was greater (P < 0.01) for BAN than INJ and BUL treatments. Consumer panelists detected a difference in perceived tenderness; BAN steaks had greater (P = 0.02) tenderness scores than BUL steaks, whereas INJ steaks were intermediate. Panelists rated juiciness of BAN steaks greater (P < 0.01) than either BUL or INJ steaks. Panelists rated beef flavor greater (P = 0.01) for BAN and BUL steaks than INJ steaks. Overall acceptability was greater (P < 0.01) for BAN compared with INJ steaks, whereas BUL steaks were intermediate. Percentage cook loss of striploin steaks (P = 0.47) and Warner-Bratzler shear force values (P = 0.11) did not differ. Cooked color lightness (L*) and redness (a*) values were not affected (P ≥ 0.23) by treatment. Striploin steaks from BAN and BUL treatments had greater (P = 0.02) yellowness values (b*) than INJ steaks. The ratio of red-to-brown (630:580 nm) of cooked striploin steaks was greater (P = 0.05) for INJ than either BAN or BUL treatments. Carcass and palatability outcomes of INJ were more similar to BUL than BAN, suggesting limited efficacy of INJ in mature beef bulls at feedlot entry.

Effects of chemical castration using 20% CaCl2 with 0.5% DMSO in tomcats: Evaluation of inflammatory reaction by infrared thermography and effectiveness of treatment

This study used infrared thermography to monitor the immediate inflammatory reaction to an intratesticular injection of 20% (calcium chloride) CaCl₂ with 0.5% dimethyl sulfoxide (DMSO) for chemical castration and to provide evidence of the treatment's clinical viability. Six animals received a 0.25 mL intratesticular injection of 20% CaCl₂ with 0.5% DMSO in each testis. Thermographic imaging, testicular measurement, penile spine evaluation, electroejaculation, and sperm analysis were performed before the injection. Eighty days post-injection, the cats were evaluated again, then received an orchiectomy followed by histological analysis. Infrared thermography of the testicular area was performed before (M0) and after anesthesia (M0A); after electroejaculation (M0E); 10 min (M1), 1 h, (M2) and 6 h (M3) after the injection for seven consecutive days (M4-10); after 15 (M11) and 30 days (M12); and after 80 days, before and after anesthesia and after electroejaculation (M13, M13A and M13E). No cats had a significant increase in testicular temperature or behavioral changes. All animals were azoospermic and had a 50% reduction in total testicular volume after 80 days. Histologically, the testes showed different degrees of degeneration, necrosis, calcification and replaced connective tissue, as well as Leydig cell hyperplasia in 7/12 of the testes. Infrared thermography efficiently diagnosed and monitored scrotal inflammation caused by intratesticular injection of 20% CaCl₂ solution with 0.5% DMSO, and it is suggested that a single injection of this compound can cause azoospermia after 80 days. We concluded by infrared thermography with a clinical exam, that the adverse reactions were minimal and did not interfere with animal welfare.

Nanocarrier-mediated delivery of α-mangostin for non-surgical castration of male animals

The overpopulation of abandoned and stray companion animals has become a global crisis. The main purpose of this study was to develop a novel nanomedicine-based antifertility compound for non-surgical castration of male animals. Mangosteen (Garcinia mangostana L) pericarp extract has been shown to exhibit anti-fertility property. α-mangostin (AM)-loaded nanostructured lipid carrier (AM-NLC) was developed to improve male germ cell apoptosis. This study was conducted to investigate physicochemical properties of AM-NLC and determine the biological effects of AM-NLC on spermatogonia cells and testicular explants obtained from castrated testes. AM-NLC was produced through a hot homogenization technique. The negatively charged particle of AM-NLC was nano-sized with a narrow dispersity. AM-NLC exhibited antiproliferative activity towards spermatogonium cells. It induced apoptosis in the cells. In addition, AM-NLC exhibited anti-inflammatory activities in lipopolysaccharide-activated macrophages. Abnormal anatomy of seminiferous tubule was noted following treatment of testicular explant with AM-NLC. This nanomedicine-based sterilant would be a promising platform that may have utility in non-surgical castration of male animals by intra-testicular injection.

4-Nitrophenol induces activation of Nrf2 antioxidant pathway and apoptosis of the germ cells in rat testes

The potential of 4-nitrophenol (PNP) to affect testicular function of rats was assessed by intratesticular injection (IT). The protective effects of phytosterin (PS) on PNP-induced injury were assessed. Rats were sacrificed on days 1, 3, and 7 after IT of PNP (0.1 M, 50 μl). PNP induced hemorrhage in intertubular areas and denudation of germinal epithelium. The expression of caspase-3 and sperm abnormalities were significantly increased (P < 0.05). The concentrations of testosterone in serum were significantly increased (P < 0.05) on the 1st and 3rd day. PNP induced oxidative stress in testes, which manifested increased SOD, CAT, GSH-Px activities, and increases in MDA, GSH, H2O2 concentrations (P < 0.05). The Nrf2 antioxidant pathway was activated as indicated by increased expression of Nrf2, HO-1, and GCLC mRNA (P < 0.05). Moreover, supplementation with PS resulted in an amelioration of PNP-induced oxidative damage. These results suggest that PNP induced activation of Nrf2 antioxidant pathway and apoptosis of the germ cells.

Intratesticular and intraepididymal injections to sterilize male cats: From calcium chloride to zinc gluconate and beyond

AIM AND RATIONALE

The aim of intratesticular and intraepididymal injections is to provide an inexpensive non-surgical method for sterilizing tom cats. Intratesticular and intraepididymal injections have been studied for decades and warrant continued investigation. While both methods result in azoospermia, intratesticular injection of sclerosing agents induces orchitis, resulting in decreased spermatogenesis, whereas intraepididymal injection blocks sperm transport but does not alter spermatogenesis.

EVIDENCE BASE

Sclerosing agents that have been used effectively for intratesticular injections in cats include calcium chloride dihydrate and zinc gluconate. For sclerosis by intraepididymal injections, chlorhexidine digluconate has been used successfully in cats. The volume, formulation and concentration of sclerosing agents for intratesticular and intraepididymal injections in cats have not been standardized.

CHALLENGES

Neither intratesticular nor intraepididymal injections entirely eliminate gonadal testosterone production, which may be undesirable for pet cats and therefore may restrict the application of this method of sterilization to feral cats with limited human contact. In addition, both methods may require sedation or general anesthesia, leading some to support routine castration over these non-surgical methods. Lastly, even if the technique is successful in inducing permanent sterility, normal fertility may persist in treated males for 1-2 months after treatment because of sperm present within the epididymis and vas deferens.