Anti-Müllerian hormone levels in serum and testes of male dogs: relations with neuter status and bilateral abdominal cryptorchidism

Anti-Müllerian hormone (AMH) analysis has contributed to new information in the reproductive endocrinology of domestic animals, due to clinically available diagnostic tools. An accurate and rapid diagnostic method to distinguish between neutered and bilateral abdominal cryptorchid dogs is needed in veterinary practice. Therefore, this study uses an enzyme-linked immunosorbent assay to evaluate the clinical relevance of AMH analysis in peripheral blood as a diagnostic tool for dogs with suspected bilateral abdominal cryptorchidism. The possible alteration of the AMH localization in testicular tissue caused by this pathologic condition was also investigated using immunohistochemistry. Male dogs were divided into three groups of healthy intact (n = 14), healthy castrated (n = 14), and bilateral abdominal cryptorchid (n = 14) dogs. The results demonstrated a higher level of serum AMH in the cryptorchid group compared to the intact group (P < 0.01), while serum AMH levels of all castrated dogs were below the limit of detection (<0.05 ng/mL). Moreover, the percentage of positive AMH immunostaining of the intact group was less than that of the cryptorchid group (P < 0.01). A significantly positive correlation was found between serum AMH concentration and localization in testicular tissues (r = 0.93, P < 0.01). Our findings suggest that AMH levels in the peripheral blood could be used as an alternative and rapid screening method for detecting dogs with abdominal cryptorchidism.

The expressions in oxytocin and sex steroid receptors in the reproductive tissues of normal and unilateral cryptorchid dogs

In males, oxytocin is involved with various physiological functions, such as reproductive tract contractility and testicular steroidogenesis. Due to the relationship between sex steroid hormones, oxytocin receptor (OTR) expression and cryptorchidism pathogenesis, this study aimed to investigate the mRNA expression and the localization of OTR in relation to sex steroid receptors in the male reproductive tract of both normal and unilateral abdominal cryptorchid dogs using quantitative PCR and immunohistochemistry. Male dogs were divided into two groups of normal and cryptorchid dogs. Samples from each cryptorchid dog were separated into two subgroups: scrotal and abdominal subgroups. The results showed that a lower percentage of positive OTR immunostaining in the testis and epididymis was observed in the cryptorchid group compared to the normal group. Within the cryptorchid group, the mRNA expression and the localization of OTR in the testis and epididymis of the abdominal subgroup was less than that of the scrotal subgroup. Moreover, the localization of OTR and estrogen receptor beta (ERβ) in reproductive tissues was positively correlated only in the normal group and not in the cryptorchid group. In conclusion, this study proposed that OTR expression, as well as the correlation between the OTR and ERβ in reproductive tissues of male dogs, can be disturbed by cryptorchidism. Furthermore, the OTR, ERβ and their correlation may be involved with the pathogenesis of cryptorchidism. Therefore, the study of gene knockout models to confirm the effect of OTR and sex steroid receptors on canine cryptorchidism should be of interest for further investigation.

GnRH-agonist implants suppress reproductive function and affects ovarian LHR and FSHR expression in prepubertal female cats

Effect of a GnRH-agonist (deslorelin) was studied on reproductive function and ovarian luteinizing hormone receptor (LHR) and follicle stimulating hormone receptor (FSHR) expression in prepubertal female cats that were either implanted with 4.7-mg deslorelin (implanted: n = 6) or not (controls: n = 18) or ovariohysterectomized at prepubertal age (prepubertal OVH: n = 6). Body weights, fecal estradiol, and sexual behavior of implanted and control cats were monitored for 48 weeks followed by collection of ovaries and uteri. Ovaries and uteri were collected from control cats at follicular, luteal, and inactive stage (n = 6/group) and from prepubertal OVH cats at prepubertal age. Ovaries and uteri were analyzed for anatomical/histological characteristics. Ovaries were also analyzed for LHR and FSHR expression. Statistical analysis showed higher (P ≤ 0.05) body weight in control than implanted cats only during 22nd to 26th weeks of the study. Estrus was observed in control cats only. Deslorelin reduced (P ≤ 0.05) ovarian weight and number of antral follicles but did not affect endometrial thickness and gland diameter. However, myometrial thickness of implanted cats was significantly lower than control cats at follicular and luteal stage. Ovarian LHR mRNA expression was lower (P ≤ 0.05) in implanted cats than control cats at follicular stage. FSHR mRNA and LHR protein expression did not differ among the three groups. FSHR protein expression was lower (P ≤ 0.05) in prepubertal OVH cats and was not affected by deslorelin. In conclusion, deslorelin suppresses reproductive function in prepubertal female cats for at least 48 weeks possibly through a change in the ovarian mRNA expression of LHR.

Expression of oxytocin, progesterone, and estrogen receptors in the reproductive tract of bitches with pyometra

Canine pyometra is considered a serious and life-threatening condition. Due to the relationship among sex steroid hormones, oxytocin receptor (OTR) expression, and canine pyometra pathogenesis, this study aimed to investigate the expression of oxytocin, progesterone, and estrogen receptors in the reproductive tissues of canines with pyometra by real-time PCR and immunohistochemistry. A total of 27 pyometra bitches were classified into open- and closed-cervix pyometra groups based on the presence of vaginal discharge. Moreover, 15 normal bitches in the luteal phase served as a control group. The results showed that OTR gene expression in the ovary of pyometra bitches was higher than that of normal bitches, whereas the level of OTR gene expression in the cervix of pyometra bitches was less than that of normal bitches (P < 0.05). Conversely, a lower OTR H-score in ovarian follicles was observed in pyometra bitches compared with normal bitches, whereas a higher percentage of OTR-positive immunostaining in uteri and cervices were found in pyometra bitches compared with normal bitches (P < 0.05). Moreover, the H-scores of estrogen receptor alpha in uteri and cervices of pyometra bitches were less than that of normal bitches (P < 0.05). However, the localization of the OTR and sex steroid receptors between groups of pyometra bitches was not different. Our findings suggest that pyometra pathogenesis is associated with a change in expression of OTR and sex steroid receptors in the canine reproductive tract. However, cervical dilation in bitches with pyometra was not influenced by the expression of OTR and sex steroid receptors.

Apoptotic Cell Localization in Preantral and Antral Follicles in Relation to Non-cyclic and Cyclic Gilts

The objective of this study was to determine apoptotic cell localization in preantral and antral follicles of porcine ovaries. Additionally, the proportion of cells undergoing apoptosis was also compared between delayed puberty gilts and normal cyclic gilts. Ovarian tissues were obtained from 34 culled gilts with age and weight of 270.1 ± 3.9 days and 143.8 ± 2.4 kg, respectively. The gilts were classified according to their ovarian appearance as 'non-cyclic' (n = 7) and 'cyclic' (n = 27) gilts. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay was used to determine apoptotic cell expression in different compartments of the ovarian tissue sections. All apparent preantral (n = 110) and antral (n = 262) follicles were evaluated using image analysis software. It was found that apoptotic cells were expressed in both granulosa (22.2%) and theca cell layers (21.3%) of the follicles in the porcine ovaries. The proportion of apoptotic cells in the granulosa layer in the follicles was positively correlated with that in the theca layer (r = 0.90, p < 0.001). Apoptosis did not differ significantly between preantral and antral follicles in either granulosa (27.8% and 26.4%, p > 0.05) or theca cell layers (28.6% and 26.5%, p > 0.05). The proportion of apoptotic cells in non-cyclic gilts was higher than cyclic gilts in both granulosa (31.7% and 22.6%, p < 0.001) and theca cell layers (34.8% and 20.2%, p < 0.001). This study indicated that apoptosis of the granulosa and theca cell layers in the follicles was more pronounced in the ovarian tissue of delayed puberty gilts than cyclic gilts. This implied that apoptosis could be used as a biologic marker for follicular development/function and also that apoptosis was significantly associated with anoestrus or delayed puberty in gilts, commonly observed in tropical climates.

Expression of progesterone receptor in the utero-tubal junction after intra-uterine and deep intra-uterine insemination in sows

The aim of this study was to investigate the expression of progesterone receptor (PR) in the utero-tubal junction (UTJ) of sows at 24 h after intra-uterine insemination (IUI) and deep intra-uterine insemination (DIUI) compared with conventional artificial insemination (AI) in pigs. Fifteen multiparous sows were used: AI (n = 5), IUI (n = 5) and DIUI (n = 5). The sows were inseminated with a single dose of diluted semen during the second oestrus after weaning at 6-8 h prior to ovulation (AI: 3000 × 10(6) spermatozoa, IUI: 1000 × 10(6) spermatozoa and DIUI: 150 × 10(6) spermatozoa). The UTJ was collected and subject to immunohistochemical staining using avidin-biotin immunoperoxidase technique with mouse monoclonal antibody to PR. In the oviductal part of the UTJ, the intensity of PR in the tunica muscularis and the proportion of PR-positive cells in the surface epithelium after DIUI were lower than AI (p < 0.05). The intensity and the proportion of PR-positive cells between AI and IUI in all compartments of the UTJ did not differ significantly (p > 0.05). When comparing between tissue compartments, prominent staining was observed in the muscular layer of the UTJ. It could be concluded that the expression of PR in the UTJ prior to fertilization after DIUI with a reduced number of spermatozoa was lower than that after AI. This might influence sperm transportation and the fertilization process.