Expression of Anti-Müllerian Hormone and Its Type 2 Receptor in the Ovary of Pregnant and Cyclic Domestic Cats

Is anti-müllerian hormone useful for monorchidism diagnosis in the tomcat?

Monorchidism is an uncommon condition in tomcats, defined by the congenital absence of one of the testicles. Due to the lack of information regarding possible biomarkers, most monorchidism cases require laparotomy in order to differentiate it from cryptorchidism. Human data suggest that monorchid patients have lower serum anti-Müllerian hormone (AMH) levels when compared to cryptorchids, premises that has been also scrutinized in veterinary medicine. Here, we describe a case of monorchidism in a tomcat, focusing on the clinical findings and the dynamics of AMH serum levels before and after the removal of the singularly identified testicle. To contribute to the limited knowledge of AMH levels across different reproductive statuses in tomcats, the findings from this monorchid case were compared to values obtained from two cryptorchid tomcats (one unilateral and one bilateral), three intact tomcats, and three castrated tomcats. In addition, clinical, histopathological and ultrasound examinations were conducted in all tomcats. The AMH levels in the monorchid tomcat revealed a consistent decrease after surgery, from 27.3 ± 0.2 ng/ml when the testicle was still present, to 2.3 ± 0.2 ng/ml 1 week later, and further decreasing below the detection limit (<0.15 ng/ml) for the last 2 weeks of the trial, matching the AMH level of the castrated male. AMH serum levels of the bilateral and unilateral cryptorchid tomcat (22.5 ± 0.3 ng/ml; 24.1 ± 0.2 ng/ml) were in agreement with those of the three intact males (19.1 ± 2.2 ng/ml) and the monorchid prior to surgery. AMH testing effectively confirmed the absence of testicular tissue after unilateral orchiectomy in a monorchid tomcat but did not differentiate between monorchidism and cryptorchidism. To our knowledge, this is the first case of monorchidism in tomcats, in which AMH levels before and after surgery have been determined.

Determination of anti-Müllerian hormone levels in blood and urine in fertile cats

In recent years, blood anti-Müllerian hormone (AMH) levels have been investigated in female animals to diagnose many conditions, such as the presence of ovarian tissue, follicle reserve, and granulosa cell tumors. Since blood collection is an invasive method, diagnosis with a non-invasive method is important in terms of practicality and animal welfare. This study aimed to investigate the presence of AMH in cat urine and determine whether a correlation exists between blood and urine AMH levels. In addition, it was aimed at revealing whether there was a change in blood and urine AMH levels according to ovarian follicle distribution. Twenty-seven healthy, fertile female cats in the follicular phase were included. Following blood and urine sample collection, a routine ovariohysterectomy was performed. Histological analysis of the removed ovarian tissue was used to determine ovarian follicle types. While both AMH and estrogen levels were determined in blood samples, only AMH levels were investigated in urine samples. Blood AMH levels averaged 10.61 ± 0.75 ng/mL (range: 5-16 ng/mL), while urine AMH levels averaged 5.67 ± 0.91 ng/mL (range: 0.2-13 ng/mL). While urinary AMH level was <1 ng/mL in 7 cats, urinary AMH was >1 ng/mL in all remaining cats. While the study demonstrated AMH excretion in urine, no correlation was found between blood and urine AMH values. However, a significant positive correlation was observed between blood AMH levels and serum estrogen levels (P < 0.001). These findings suggest that urinary AMH may be a product of proteolytic degradation, potentially leading to inaccurate estimations of ovarian activity based solely on urine AMH levels.

Abundance of Anti-Muellerian hormone in cat ovaries and correlation of its plasma concentration with animal age, weight and stage of the estrous cycle

In female animals of different species, Anti-Müllerian hormone (AMH) is produced by follicular granulosa cells and has been associated with the ovarian follicle pool. Because concentration of AMH in plasma of ovary-intact female cats is apparently more variable than previously assumed, we have analysed AMH concentration in blood of cats (n = 93) presented for routine ovariectomy and assessed ovarian histology and AMH protein expression in the surgically removed ovaries. We hypothesised that AMH is synthesized only in preantral and small antral follicles and that plasma AMH concentration reflects the antral follicle count (AFC). Corpora lutea were detected in 35% of the female cats, whereas plasma progesterone concentration was ≥1 ng/mL in 57% of the cats. Follicular cysts were present in 15 cats (16%). Positive immunostaining for AMH protein was detected in close to all primordial and antral follicles, ovarian cysts, 70% of corpora lutea and 28% of atretic follicles. Concentration of AMH in plasma averaged 6.8 ± 0.5 ng/mL (range 1.3-21.7 ng/mL). The AFC increased with increasing AMH concentration with a moderate positive correlation between AFC and AMH (r = 0.286, p < 0.01). Plasma AMH concentration was not affected by season or cats' age, weight, stage of the estrous cycle and presence of follicular cysts. In conclusion, AMH protein is expressed in all endocrine structures of the cat ovary. While AMH is a marker for the presence of ovarian tissue, its usefulness to assess ovarian function in individual female cats is of limited value.

Molecular Factors Involved in the Reproductive Morphophysiology of Female Domestic Cat (Felis catus)

The domestic cat (Felis catus) is considered an important model for the study of feline reproductive morphophysiology. However, although the morphological changes and clinical signs that occur during the estrous cycle and pregnancy are well known, little is known about the molecular mechanisms involved in the reproductive physiology of this animal species. Thus, this paper reviews the current knowledge about the modulation and expression profile of hormonal, immunological, redox, and growth mediators involved in the uterine, ovarian, and placental morphophysiology of domestic cats.

Durable contraception in the female domestic cat using viral-vectored delivery of a feline anti-Müllerian hormone transgene

Eighty percent of the estimated 600 million domestic cats in the world are free-roaming. These cats typically experience suboptimal welfare and inflict high levels of predation on wildlife. Additionally, euthanasia of healthy animals in overpopulated shelters raises ethical considerations. While surgical sterilization is the mainstay of pet population control, there is a need for efficient, safe, and cost-effective permanent contraception alternatives. Herein, we report evidence that a single intramuscular treatment with an adeno-associated viral vector delivering an anti-Müllerian hormone transgene produces long-term contraception in the domestic cat. Treated females are followed for over two years, during which transgene expression, anti-transgene antibodies, and reproductive hormones are monitored. Mating behavior and reproductive success are measured during two mating studies. Here we show that ectopic expression of anti-Müllerian hormone does not impair sex steroids nor estrous cycling, but prevents breeding-induced ovulation, resulting in safe and durable contraception in the female domestic cat.

Serum antimüllerian hormone concentrations in female cats. Relation with ovarian remnant syndrome, ovarian cysts and gonadectomy status

The aim of this study was to reveal (1) the determination of the serum antimüllerian hormone concentrations in cats with ovarian remnant syndrome and ovarian cyst, (2) the effectiveness of the serum antimüllerian hormone concentrations in detecting gonadectomy status, and (3) ovarian expression of the antimüllerian hormone in the ovarian cysts and ovarian remnant tissue. For this purpose, a total of 31 domestic cats older than 1 year, including ORS (n = 9), OC (n = 3), spayed (n = 8), and intact (n = 11), were used in the study. Serum and intrafollicular AMH concentrations were determined by the electrochemiluminescence immunoassay, and expression of the AMH was determined by the immunohistochemical method. The serum AMH concentration in the ORS group was 1.49 ± 1.24 ng/ml (0.10-3.63 ng/ml) whereas it was 1.78 ± 0.92 ng/ml (0.8-2.63 ng/ml) in the OC group. AMH concentration in the intrafollicular fluid was determined as 0.023 ng/ml in a cat with an ovarian cyst. While the serum AMH concentration was below 0.01 ng/ml in spayed cats, it was 5.80 ± 3.30 ng/ml (1.88-11.86 ng/ml) in the intact cats. There was a significant difference between the spayed and intact groups in terms of serum AMH concentration (p < 0.05). Moreover, in cats with ovarian cyst and ovarian remnant syndrome, no difference was found between the groups in terms of serum AMH concentration (p > 0.05). No difference was found between the ovarian remnant syndrome and intact cats in terms of serum AMH concentration (p > 0.05). In immunohistochemical staining, ovarian cysts were found to be negative for AMH while a moderate (+2) AMH positivity was observed in other follicles. Furthermore, in cats with ovarian remnant syndrome, severe (+3) AMH positivity was observed. As a result, it was determined that gonadectomy status can be accurately diagnosed by the AMH measurement. Ovarian remnant syndrome cannot be diagnosed accurately by AMH measurement. In addition, it was found that AMH did not seem to play a role in the pathogenesis of ovarian cysts in cats.

Anti-Müllerian hormone in queens: Serum concentrations and total ovarian follicle population

The objectives of this study were: a) To report anti-Müllerian hormone (AMH) serum concentrations in neonatal, pre and postpubertal female cats. b) To establish the relationship between serum AMH with either age and estrous cycle c) To correlate the total number of different ovarian follicle types with AMH in adult queens. A single blood sample was collected from 10 neonates (including 5 male), 15 prepubertal and 48 postpubertal female cats to measure AMH. Eight, 10, and 18 of this latter group were in follicular (FP), luteal phase (LP), and anestrus (AN), respectively. The total number of each follicle type was histologically counted using the Gougeon and Chainy (1987) formula in a subgroup of 10 adult queens. Overall AMH mean of these the female cats was 6.31 ± 0.54 ng/mL. The neonatal females had lower AMH serum concentrations than their male littermates (2.56 ± 0.49 vs. >23 ng/mL; P < 0.01). Concentrations were also higher in prepubertal than in neonatal and postpubertal cats (11.79 ± 1.36 vs. 2.56 ± 0.49 vs. 4.87 ± 0.38 ng/mL; P < 0.01). Queens below 12 mo of age had the highest AMH levels (10.41 ± 1.16; P < 0.01). Age was inversely correlated with AMH (r = -0.5; P < 0.01). Animals in FP had lower AMH concentrations than AN females (2.51 ± 0.33 vs. 5.46 ± 0.76 ng/mL; P < 0.05). No difference in the total number of each follicle type were found between either ovary (P > 0.05). A high correlation was only found between small antral follicles and AMH concentrations (r = 0.85; P < 0.01). It was concluded, that AMH can provide an indirect, reliable marker for the assessment of ovarian follicle size and functionality. Age as well as pubertal state should be considered when evaluating AMH concentrations in this species.

Role of anti-Mullerian hormone in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common gynecological endocrine disorders affecting up to 10% of all females in their reproductive age, and its cause of onset is still elusive. A spectrum of recent research reflected diverse associations between increased plasma level of anti-Mullerian hormone (AMH) and different clinical features of PCOS. Since AMH levels reflect the pool of growing follicles that potentially can ovulate, it can be stated that serum AMH levels can be used to assess the “functional ovarian reserve,” rather mentioning it as the “ovarian reserve.” AMH also appears to be a premier endocrine parameter for the assessment of atrophied ovarian follicular pool in response to age of individuals. AMH hinders the follicular development as well as the follicular recruitment and ultimately resulting in follicular arrest which is the key pathophysiologic condition for the onset of PCOS. Furthermore, FSH-induced aromatase activity remains inhibited by AMH that aids emergence of other associated clinical signs of PCOS, such as excess androgen, followed by insulin resistance among the PCOS individuals. Given the versatile association of AMH with PCOS and scarcity in literature explaining the underling mechanisms how AMH relates with PCOS, this review article will discuss the roles of AMH in the pathogenesis of PCOS which may introduce a new era in treatment approach of PCOS.