Plasma concentrations of progesterone, oestrogens, testosterone and LH-like activity during the oestrous cycle of the camel (Camelus dromedarius)

Follicular fluid and serum biochemical and hormonal profiles of normal and cystic dromedary camel breeds

Background and Aim

Ovarian cysts (OC) in female dromedary camels have been described as problematic because they can cause infertility. This study aimed to compare the hormone concentrations and biochemical contents present in serum and follicular fluid of normal and cystic she-dromedaries of the two most common Algerian camel breeds (Sahraoui and Targui) to gain a better understanding of biological differences that may yield insights into preventing or treating this ovarian abnormality.

Materials and Methods

At an abattoir in southeastern Algeria, 100 pairs of the same females' ovaries and blood samples were taken immediately after the slaughter of clinically healthy, non-pregnant females (8-15 years old) over two consecutive breeding seasons (November 2017-April 2018 and November 2018-April 2019). The concentrations of glucose, cholesterol, protein, urea, creatinine, triglyceride, gamma-glutamyl transferase, alanine aminotransferase, and aspartate aminotransferase were determined using commercial diagnostic kits and standard analytical procedures. Electrochemiluminescence immunoassay was used to measure progesterone (P4) and insulin concentrations.

Results

The concentrations of glucose, insulin, cholesterol, and P4 in sera and follicular fluid (regardless of ovarian follicle diameter) were different (p < 0.001), but there was no significant difference in the other parameters studied. Glucose, insulin, cholesterol, urea, and P4 levels in blood serum differed significantly from pre-ovulatory follicles. None of the biochemical and hormonal components measured differed significantly between the pre-ovulatory and cystic fluids of the she-dromedaries studied. The breed did not affect the biochemical and hormonal composition of she-dromedary cystic and follicular fluids.

Conclusion

Ovarian cysts appear to form in a metabolic milieu distinct from follicular fluid and blood serum, with no influence from camel breeds. It is suggested that further research on the blood-follicle barrier be conducted to gain a better understanding of the OC development process in she-dromedaries.

Clinical and Correlated Responses among Steroid Hormones and Oxidant/Antioxidant Biomarkers in Pregnant, Non-Pregnant and Lactating CIDR-Pre-Synchronized Dromedaries (Camelus dromedarius)

Overproduction of free radicals is controlled by antioxidant defense mechanisms. These defense mechanisms are achieved by antioxidant enzymes such as catalase (CAT). The current study aimed to assess the changes in steroid hormones, oxidant/antioxidants biomarkers, lipid profiles/liver functions indices, renal function biomarkers and minerals metabolism in non-pregnant, lactating or pregnant one-humped she-camels (Camelus dromedarius) pre-synchronized with controlled internal drug releasing. The study also focused on the correlational relationships between steroid hormones and the oxidant/antioxidant biomarkers, lipid profiles and liver functions indices, renal functions and mineral metabolism in these she-camels. The study was conducted on apparently healthy dromedary she-camels (n = 60) during breeding season. A sexually active camel-bull was introduced to she-camels pre-synchronized with CIDR. Fifty to sixty days after natural mating, she-camels were examined for pregnancy. She-camels were divided into three main groups according to both pregnancy and lactation as following: pregnant (PREG, n = 38) which was kept as control one, non-pregnant and lactating (LACT, n = 8), and non-pregnant and non-lactating she-camels (NPREG, n= 14). Steroid hormones, i.e., progesterone (P₄), estradiol (E₂) and cortisol, oxidant indictors, i.e., malondialdehyde (MDA), antioxidant biomarkers, i.e., superoxide dismutase (SOD), total antioxidant capacity (TAC), CAT and reduced glutathione (GSH), lipid profiles indices, renal functions and related minerals were assessed. The present study confirmed the efficacy of using CIDR for synchronization in she-camels. Significant elevations in serum steroids hormones in PREG compare with LACT and NPREG. The highest concentrations of MDA as lipid peroxidation and oxidative stress indictors and lowest levels of antioxidant biomarkers except for SOD, i.e., TAC, CAT and GSH, were reported in PREG compared with LACT and NPREG. PREG showed the highest liver enzymes activities and lowest total protein values. Remarkable increases in serum concentrations of renal function parameters and phosphorous (P) were observed in PREG when compared with the other two groups. The investigated she-camels revealed significant correlation between steroid hormones and the oxidant biomarkers, antioxidant biomarkers, liver functions, renal functions and minerals metabolism parameters. P₄ showed positive correlations with antioxidant biomarkers, i.e., TAC, CAT and GSH, and serum aspartate aminotransferase (AST) activities, whereas negative correlations were reported between P₄ and renal functions biomarkers, i.e., blood urea nitrogen (BUN), creatinine (Cr) and creatinine kinase (CK), and minerals metabolism parameters, i.e., P and magnesium (Mg), in CIDR pre-synchronized she-camels. In contrast, E₂ and cortisol showed negative correlations with antioxidant biomarkers, i.e., TAC, CAT and GSH, lipid profiles/liver functions indices, i.e., AST, alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT), CK and Mg, however, positive correlations were demonstrated between E₂ and cortisol, and MDA, Cr and P in investigated she-camels. In conclusion, the present study confirmed the efficacy of using CIDR for synchronization in she-camels. The highest MDA levels as indictors for oxidative stress and the lowest antioxidant levels, i.e., TAC, CAT and GSH, except for SOD in pregnant she-camels, were attributable to physiological oxidative stress as excellent compensatory responses observed in the PREG group to face such a physiologic stage. Moreover, lower P levels in non-pregnant she-camels would be contributed to failure of conception or early embryonic death. The investigated she-camels revealed significant correlations between steroid hormones and the oxidant indicators, antioxidant biomarkers, lipid profile indices and renal functions biomarkers that provided better understanding for physiological stress during pregnancy in camels.

Effect of exogenous progesterone treatment on ovarian steroid hormones and oxidant and antioxidant biomarkers during peak and low breeding seasons in dromedary she-camel

Background:

Research about the effects of progesterone (P₄) and the relationship of P₄ to oxidative stress has been achieved in ruminants but not enough in camels.

Aim:

This study evaluated the effect of exogenous P₄ hormone using CIDR for 7 days on blood concentrations of steroid hormones and oxidative status of dromedary she-camels during peak and low breeding seasons.

Materials and Methods:

The present work was conducted on ten dark dromedary she-camels which were synchronized using a controlled internal drug release (CIDR) for 7 days as a reproductive management tool during peak breeding (November-April) and low breeding season (May-October). The blood samples were collected each other day from CIDR insertion until the end of experiment 5 days after the removal of CIDR. Camels were examined for P₄, estradiol (E₂), and testosterone (T) as well as malondialdehyde (MDA) as indicator of lipid peroxidation and nitric oxide, superoxide dismutase (SOD), and glutathione-S-transferase as antioxidant markers.

Results:

Results revealed that P₄ was higher during peak breeding season than low breeding season. While the levels of P₄ increased during CIDR insertion and declined at CIDR removal and thereafter during breeding season, its concentrations declined after CIDR application during the non-breeding season. On the other hand, blood E₂ and testosterone levels decreased after CIDR insertion in both high and low breeding seasons with higher serum E₂ concentrations during the peak than the low breeding season. MDA concentrations and SOD activities were significantly (p<0.05) high on day 3 after CIDR insertion during the breeding and non-breeding seasons. During both the seasons, GSH levels decreased after CIDR removal in camels. However, MDA was lower during non-breeding season than high breeding season with no seasonal effect on SOD activity.

Conclusion:

Exogenous P₄ treatment through CIDR in dromedary camels could be more efficient during breeding season than non-breeding season, and effects on circulating oxidant/antioxidant biomarkers and their return to normal levels might refer to the adaptation of camels to CIDR by modulating their oxidant and antioxidant levels.

Effect of Melatonin Implants during the Non-Breeding Season on the Onset of Ovarian Activity and the Plasma Prolactin in Dromedary Camel

To examine a possible control of reproductive seasonality by melatonin, continual-release subcutaneous melatonin implants were inserted 4.5 months before the natural breeding season (October-April) into female camels (Melatonin-treated group). The animals were exposed to an artificial long photoperiod (16L:8D) for 41 days prior to implant placement to facilitate receptivity to the short-day signal that is expected with melatonin implants. The treated and control groups (untreated females) were maintained separately under outdoor natural conditions. Ovarian follicular development was monitored in both groups by transrectal ultrasonography and by plasma estradiol-17β concentrations performed weekly for 8 weeks and then for 14 weeks following implant insertion. Plasma prolactin concentrations were determined at 45 and 15 days before and 0, 14, 28, 56, and 98 days after implant insertion. Plasma melatonin concentration was determined to validate response to the artificial long photoperiod and to verify the pattern of release from the implants. Results showed that the artificial long photoperiod induced a melatonin secretion peak of significantly (P < 0.05) shorter duration (about 2.5 h). Melatonin release from the implants resulted in higher circulating plasma melatonin levels during daytime and nighttime which persisted for more than 12 weeks following implants insertion. Treatment with melatonin implants advanced the onset of follicular growth activity by 3.5 months compared to untreated animals. Plasma estradiol-17β increased gradually from the second week after the beginning of treatment to reach significantly (P < 0.01) higher concentrations (39.2 ± 6.2 to 46.4 ± 4.5 pg/ml) between the third and the fifth week post insertion of melatonin implants. Treatment with melatonin implants also induced a moderate, but significant (P < 0.05) suppressive effect on plasma prolactin concentration on the 28th day. These results demonstrate that photoperiod appears to be involved in dromedary reproductive seasonality. Melatonin implants may be a useful tool to manipulate seasonality and to improve reproductive performance in this species. Administration of subcutaneous melatonin implants during the transition period to the breeding season following an artificial signal of long photoperiod have the potential to advance the breeding season in camels by about 2.5 months.

Immunohistochemical localization of androgen and progesterone receptors in the uterus of the camel (Camelus dromedarius)

Ten adult, cyclic female camels (Camelus dromedarius) were used to describe the distribution of androgen (AR) and progesterone (PR) receptors in the uterus using immunohistochemistry. Both AR and PR were distributed throughout the different compartments of the uterus with nuclear staining for AR and PR seen in the cells of epithelia (luminal and glandular), stroma and myometrial smooth muscles. AR immunostaining was not uniform in distribution and intensity; the surface epithelium and the glandular epithelium in the adluminal region of the endometrium showed lower AR immunoreactivity than other compartments of the uterus. PR immunostaining showed uniformity in both distribution and intensity strong PR immunostaining intensity in almost all cells of the different uterine compartments. The intensity and distribution of PR immunostaining in epithelia of lumen and glands in the adluminal regions of endometrium was higher (P<0.05) than that of AR. In conclusion, immunohistochemical localization of AR and PR in the uterus of the cyclic dromedary camel indicates the important roles of androgen and progesterone in controlling the uterine activity during the follicular phase.

Reproductive physiology in female Old World Camelids

This review summarizes the basic reproductive physiology of dromedary and Bactrian camels. Camels are seasonal breeders with a relatively short breeding season during the cooler months. The onset of the breeding season can be influenced by local environmental factors such as temperature and pasture availability although decreased libido of the male as the environmental temperature increases is also a factor. Oestrous behaviour is highly variable in duration and intensity and is therefore unreliable for the detection of oestrus and difficult to relate to follicular activity in the ovaries. Camels are induced ovulators and thus normally only ovulate in response to mating. In the absence of mating, ovarian follicles tend to regress after a period of growth and maturity, whereas if male and females are kept together the female gets mated when the dominant follicle measures between 1.3 and 1.7 cm in diameter and the corpus luteum that develops has a lifespan of only 10-12 days. Peripheral concentrations of oestradiol increase with increasing follicle diameter until the follicle reaches 1.7 cm in diameter at which time they start to decrease even if the follicle continues to grow. The concentrations of progesterone remains low in non-mated animals but in mated camels it increases 3-4 days after ovulation (day of ovulation=Day 0) to reach maximum concentrations on Days 8-9 before decreasing rapidly on Days 10-11 in the non-pregnant animal. Ovulation can also be reliably induced using either Gonadotrophin Releasing Hormone (GnRH) or human Chorionic Gonadotrophin (hCG) but only when the follicle measures between 1.0 and 1.9 cm in diameter. Ovulation does not typically occur from follicles that grow beyond 2.0 cm in diameter but these follicles typically develop echogenic strands of fibrin as the follicle degenerates. The gestation period of camels is 13 months but the time of resumption of follicular activity following parturition is highly variable and influenced by nutritional status and lactation. Females that lose their offspring or have offspring which are weaned have a mature follicle develop within 10-12 days, whilst in well-fed lactating females mature follicles do not develop until 30-60 days postpartum.

Comparison of the effect of ovulation-inducing factor (OIF) in the seminal plasma of llamas, alpacas, and bulls

We have recently reported the presence of an ovulation-inducing factor (OIF) in the seminal plasma of llamas and alpacas-species characterized as induced ovulators. The study was designed to test the hypothesis that the seminal plasma of bulls will induce ovulation in llamas, and to compare the ovulation-inducing effect of seminal plasma of conspecific versus hetero-specific males. The seminal plasma of alpacas, a closely related induced ovulator (Lama pacos), and cattle, a distantly related ruminant species (Bos taurus) considered to be spontaneous ovulators, were compared with that of the llama (Lama glama). Ovulation and maximum corpus luteum diameter were compared by ultrasonography among female llamas (n=19 per group) treated intramuscularly with 2 mL of phosphate buffered saline (PBS, negative control) and those treated with 2 mL of seminal plasma of bulls, alpacas, or llamas (conspecific control). The diameter of the preovulatory follicle did not differ among groups at the time of treatment. Bull seminal plasma induced ovulations in 26% (5/19) of llamas compared to 0% (0/19) in PBS group (P<0.001). The proportion of females that ovulated was lower (P<0.01) in bull seminal plasma group compared to the groups treated with alpaca or llama seminal plasma (100%). A corpus luteum was detected on Day 8 (Day 0=treatment) in all llamas in which ovulation was detected earlier (Day 2) by ultrasonography. The diameter of the CL did not differ among groups. Results document the presence of an ovulation-inducing factor in the seminal plasma of B. taurus. The interspecies effects of seminal plasma on ovulation and luteal development provide rationale for the hypothesis that OIF is conserved among both spontaneous and induced ovulating species.

Pharmacokinetics of progesterone in dromedary camels (Camelus dromedarim)

The effect of ovariectomy or administration of progesterone (P4) on the disposition kinetics of P4 was determined in dromedary camels. The disappearance of P4 from peripheral circulation of the camel following ovariectomy or after a single intravenous (I.V.) injection of 1 mg kg(-1) body weight followed a bioexponential curve. Both curves were parallel indicating that the disappearance of injected P4 behaved similarly to endogenous P4. The mean (+/- SD) half-life calculated from the slower component of this decline, was 26.0 +/- 2.0 min after I.V. injection of P4 and 28.0 +/- 2.1 min after ovariectomy. The apparent volume of distribution (1370 ml kg(-1)) exceeded total body water suggesting extensive tissue penetration.

The concentrations of LH, FSH, oestradiol-17beta and progesterone in the blood plasma of the female Bactrian camel (Camelus bactrianus) before and after intramuscular injection of seminal plasma

The concentrations of LH, FSH, oestradiol-17beta and progesterone in the blood plasma of the female Bactrian camel (Camelus bactrianus) before and after intramuscular injection of seminal plasma.

Reproduction in Old World camels

The article reviews aspects of the basic reproductive biology of the camel, such as puberty, breeding season, ovarian dynamics, synchronisation of ovarian activity and artificial insemination, and superovulation and embryo transfer. Pregnancy and parturition are also discussed.

Seasonal effects on fertility and ovarian follicular growth and maturation in camels (Camelus dromedarius)

Camels are said to be seasonal breeders, but the extent to which season interferes with food supply to affect ovarian function is not fully documented. Hence, the three aims of this study were: (1) to define the breeding season of camels maintained in semi-arid conditions in southern Morocco; (2) to relate the proportion of females with active ovaries (i.e., with follicles > 5 mm), with ovulatory (11-17 mm) or cystic (> 18 mm) follicles to age and body conditions score; (3) to study the consequences of the interactions between age and body conditions score on the proportion of females ovulating and conceiving; and (4) to compare follicular maturation, using in vitro steroidogenesis by intact follicles as a marker during the transition into the breeding season (October) and peak breeding season (March). There was a clear breeding season in the two flocks studied, since over 80-90% of the matings occurred during the period from mid-November to mid-April. Collection of ovaries at slaughter (n = 238) demonstrated a significant seasonal effect on the proportion of females with active ovaries (increasing from 73.5% in October-December to 89% in January-May), but no changes in the proportion of females with ovulatory follicles. Lean females (BCS < 2.5) had a delayed initiation of ovarian function in October-December. In addition, the proportion of females with cystic follicles was also affected by season (peaking during April-May). Neither age nor body condition modulated the frequency of cysts. Finally, the proportion of females conceiving increased steadily as season progressed (peaking at 57% in April-May). Body condition score did not affect this proportion, but young females (< or = 5 years old) had a low ability to conceive. Morphological features of large follicles were unaffected by season. Ovulatory follicles contained around 10(7) granulosa and theca cells. In vitro testosterone output by intact follicles was unrelated to follicle size and season. In vitro oestradiol output increased with increasing follicle size and was larger in follicles obtained during peak breeding season than at its initiation. This may indicate that early breeding season follicles display a low aromatase activity in their granulosa cells. Whether the low oestradiol output of early breeding season follicles is resulting in the low fertility observed at this period remains to be determined.

Effects of low doses of oestradiol, testosterone and dihydrotestosterone on the immune response of broiler chicks

Administration of either 1 microgram kg-1 BW oestradiol 17 beta (E2), 0.1 mg kg-1 BW testosterone (T) or 0.2 mg kg-1 BW dihydrotestosterone (DHT) in feed to broiler chicks for 50 days caused increased serum concentration of the hormones compared to the control birds that were given no drugs. E2 and T but not DHT resulted in a significant decrease of the total number of leukocytes, lymphocytes and the weight of bursa of Fabricious. The hormones significantly reduced the macrophage phagocytic activity compared to controls. It is suggested that prolonged administration of low doses of E2 and T but not DHT to chicken may induce immunosuppressant effect.

Uterine activity after ovariectomy in the camel (Camelus dromedarius): effect of exogenous administration of oestrogen and progesterone

During oestrous cycles of the camel, spontaneous uterine contractions were correlated significantly with plasma oestradiol-17 beta concentration. Ovariectomy in the camel resulted in a decreased plasma concentration of oestradiol-17 beta (< 15 pg ml-1) and progesterone (< 0.1 ng ml-1) and caused complete cessation of uterine activity. Daily administration of oestradiol benzoate (5 mg, intramuscularly) increased the plasma concentration of oestradiol-17 beta (> 45 pg ml-1) and increased the frequency and amplitude of uterine activity. Coadministration of progesterone (100 mg, intramuscularly) increased the plasma concentration of progesterone (> 4 ng ml-1) and increased the frequency but not amplitude of uterine activity. It is suggested that uterine activity in the camel is correlated with the circulating levels of oestradiol-17 beta and progesterone.