The in-vitro effect of gonadotropin-releasing hormones, GnRH-I and GnRH-II, on the motility, vitality and acrosome integrity of Vervet monkey (Chlorocebus aethiops) spermatozoa.

Two isoforms of the gonadotropin-releasing hormone (GnRH), GnRH-I and GnRH-II, are expressed in mammals, and the presence of one or more GnRH-like peptides has been demonstrated in the male reproductive tract. GnRH and its receptors (GnRHR) are present in human and non-human primate testis, prostate, epididymis, seminal vesicle, spermatozoa and seminal human plasma. GnRH-II is site-specific and acts directly in an inhibitory or stimulatory fashion. Previous studies speculated that GnRH-II could disrupt specific sperm processes, such as sperm motility or capacitation and could be utilized as an effective contraceptive agent. Our study aimed to investigate the in-vitro effects of GnRH-I and GnRH-II on Vervet monkey sperm function. Electro-ejaculated semen samples from 10 Vervet monkeys (Chlorocebus aethiops) were used to select motile sperm populations. Sperm aliquots were incubated with GnRH-I and GnRH-II at different concentrations for 1 h, where after sperm motility and kinematic parameters were assessed using the automated Sperm Class Analyser. Additional sperm aliquots were incubated with two 10-amino acid control peptides, a non-related peptide and an inactive peptide to exclude the possible influence on sperm motility from other peptides with a structure similar to GnRH. Additionally, a GnRHR-I antagonist (GnRHR-A), Cetrorelix, was tested to establish its antagonistic capability on GnRH. The effect of selected concentrations of GnRH-I and GnRH-II on sperm vitality and acrosome intactness was also evaluated after 10- and 60 min exposure. Analysis of the percentage total sperm motility revealed that different concentrations for GnRH-I and GnRH-II inhibited sperm motility significantly. While sperm progressiveness was also notably affected and a trend of decreased sperm kinematics were evident, no effect was found on sperm vitality or acrosome intactness. The non-related and inactive peptides had no impact on sperm motility. The GnRHR-A demonstrated no effect on sperm motility and effectively blocked the inhibitory outcome on the motility of both GnRH isoforms. While GnRH-I or GnRH-II at low-dose concentrations resulted in in-vitro inhibition of sperm motility, it appears to have no adverse effects on other sperm functional parameters evaluated. These collective observations possibly indicate an essential role for GnRH in the in-vivo process of sperm selection in the female reproductive tract.

Effect of Copper Sulphate and Cadmium Chloride on Non-Human Primate Sperm Function In Vitro.

In order to address the large percentage of unexplained male infertility in humans, more detailed investigations using sperm functional tests are needed to identify possible causes for compromised fertility. Since many environmental and lifestyle factors might be contributing to infertility, future studies aiming to elucidate the effect of such factors on male fertility will need the use of appropriate research models. The current study aimed to assess the effects of two heavy metals, namely copper sulphate, and cadmium chloride, on non-human primate (NHP) sperm function in order to establish the possibility of using these primate species as models for reproductive studies. Our combined results indicated that the functionality of NHP spermatozoa is inhibited by the two heavy metals investigated. After in vitro exposure, detrimental effects, and significant lowered values (p < 0.05) were obtained for sperm motility, viability and vitality, acrosome intactness, and hyperactivation. These metals, at the tested higher concentrations, therefore, have the ability to impair sperm quality thereby affecting sperm fertilizing capability in both humans and NHPs.

The expression of type I and II gonadotropin-releasing hormone receptors transcripts in Vervet monkey (Chlorocebus aethiops) spermatozoa.

Gonadotropin-Releasing Hormone (GnRH), acting via the GnRH receptor (GnRHR), and a member of G-protein coupled receptor (GPCR), plays an essential role in the control of reproduction while operating primarily at the hypothalamic level of the gonadotropic axis. GnRH and its receptor are co-expressed in certain specific cells, suggesting an autocrine regulation of such cells. In the male reproductive system, two forms of GnRH (I and II) and its receptors (GnRHR) are present in the human and non-human primate (NHP) testis, prostate, epididymis, seminal vesicle, and human spermatozoa. In humans, the GnRHR-II receptor gene is disrupted by a frameshift in exon 1 and a stop codon in exon 2, rendering the receptor non-functional, whereas a fully functional GnRHR-II receptor is present in New-World and Old-World monkeys. There is no evidence of the existence of a GnRH receptor in NHP sperm. Since the NHP has a phylogenetic relationship to man and is often used as models in reproductive physiology, this present study aimed to determine GnRHR-I and GnRHR-II in Vervet monkey (Chlorocebus aethiops) spermatozoa. A total of 24 semen samples were obtained from four adult Vervet monkeys through electro-ejaculation and utilized for genotyping and gene expression analysis of GnRHR-I and II. Here we report that both receptors were successfully identified in the Vervet monkey sperm with the abundance of GnRHR-I gene expression compared to GnRHR-II. In comparison to the human, there is no evidence of such a stop codon at position 179 in exon 2 of the Vervet GnRHR-II. These findings suggest that both receptors are transcriptionally functional in Vervet spermatozoa.

The Beneficial Role of Anchomanes difformis in STZ-Induced Reproductive Dysfunction in Male Wistar Rats.

BACKGROUND: Progression of diabetes mellitus has increasingly led to several diabetic complications. Diabetes is one of the major factors implicated in male reproductive system damage. Recent approaches such as the use of medicinal plants have been explored in the management of diabetes and associated complications. Anchomanes difformis (common name: children's umbrella) has been shown to possess anti-diabetic ability in animal model. Therefore, this study seeks to investigate the potency of Achomanes difformis in ameliorating diabetes-induced reproductive dysfunction. METHODS: Type 2 diabetes was induced in male Wistar rats with 10% fructose administration for 2 weeks and an intraperitoneal injection of 40mg/kgBW of streptozotocin. Aqueous extract (200mg and 400mg/kgBW) of Anchomanes difformis leaves was administered daily for 6 weeks. The rats were randomly divided into 7 groups with a minimum of eight rats in each (8 rats in normal groups and 10 in diabetic groups). The impact of diabetes and treatment was investigated by estimating sperm concentration, motility indices, viability and morphological parameters in the normal, treatment controls and diabetic rats using CASA-SCA system. Histological examination of the testes and epididymis was performed. RESULTS: Diabetes induction resulted in significant decrease in sperm concentration, viability and some motility parameters with 40% abnormalities in sperm morphology. The administration of Anchomanes difformis significantly increased sperm concentration and sperm viability, while it significantly improved the percentage of morphologically normal sperm in diabetic rats. Anchomanes difformis ameliorated testicular damage such as vacuolization and loss of germinal epithelium in the diabetic-treated rats when compared to the diabetic controls. CONCLUSION: The potency Anchomanes difformis displayed against diabetic-induced damage in the reproductive system might be a new and promising tool in the management of male reproductive dysfunctions and associated complications in diabetes mellitus.

A comparison between the semen and sperm parameters from the captive-bred Vervet monkey (Chlorocebus aethiops) and Rhesus monkey (Macaca mulatta).

BACKGROUND: It is generally accepted that non-human primates (NHP) represent the model of choice for integrative studies of testicular function and endocrine control. However, there are many species-specific differences that necessitate identification prior to the selection of an appropriate model for these studies. In an NHP breeding facility, this opportunity of selection is usually presented during breeding periods when it is crucial to determine which individuals should be maintained as breeders. With reference to adult males and their use in breeding programs and reproductive studies, it is therefore imperative to document the normal semen and sperm values, expected seasonal changes and the variabilities found within samples and among individuals. The comparison of closely related species that differ by breeding seasonality will, therefore, highlight their value in reproductive research. METHODS: Semen samples were obtained by rectal probe electroejaculation (RPE). The seminal and sperm characteristics of captive-bred Vervet monkeys (Chlorocebus aethiops) (n = 10) and Rhesus monkeys (Macaca mulatta) (n = 10) were evaluated and compared. Parameters such as semen volume, pH, sperm concentration, and sperm motility were analyzed by means of a computer-aided sperm analysis (CASA) system. RESULTS: Large variations in semen and sperm parameter values indicated differences between species and samples. Monthly variations were observed for the Vervet regardless of breeding and conceptions that occurred throughout the year. In contrast, Rhesus seminal characteristics indicated a clear seasonal trend. CONCLUSION: Non-human primates have long provided as research models for studying complexities of human reproductive biology. The baseline values reported from this study can be applied as guidelines during the selection of male individuals for reproductive studies. Of further interest is the comparative data on semen and sperm parameters between two congeneric species that differ by seasonal versus aseasonal breeding.

Faecal glucocorticoid metabolite monitoring as a measure of physiological stress in captive and wild vervet monkeys.

The development of non-invasive techniques to analyse physiological stress in mammalian species has revolutionised field-based endocrinology. However, careful validation of the methods used to determine faecal glucocorticoid metabolite (fGCM) and other hormone concentrations are required on a species- and sex-specific basis. In this study, we performed an adrenocorticotropic hormone (ACTH) stimulation test on four (two male and two female) captive vervet monkeys (Chlorocebus pygerythrus) to determine the most appropriate enzyme immunoassay (EIA) from a suite of available EIAs. Furthermore, we took advantage of a potentially stressful event in our wild vervet population from Samara Private Game Reserve, South Africa, to examine if an alpha-beta female rank reversal increases the physiological stress of those individuals directly involved, as well as other group members. Both our physiological and biological validation studies revealed that a cortisol assay was the most appropriate EIA for monitoring fGCM alterations in vervet monkeys. In addition, we found that the observed rank-reversal had no significant effect on the physiological stress levels of uninvolved group members. Our study highlights that physiological validation is imperative and, where possible, should be conducted in parallel with a carefully considered biologically-relevant test under natural conditions. Overall, our results provide a necessary step for future studies to examine physiological stress of vervet monkeys via fGCM monitoring by validating a suitable EIA for this species. This paves the way for future research into the health and welfare of both captive and wild vervet monkeys, and will allow researchers to assess the behavioural, social and ecological correlates of physiological stress levels of this species.

The effect of housing and environmental enrichment on stereotyped behavior of adult vervet monkeys (Chlorocebus aethiops).

Little information is available on the response of vervet monkeys to different housing conditions or on the suitability of enrichment devices or methods for vervet monkeys. In this study, the authors evaluated the occurrence of stereotyped behavior in adult vervet monkeys under various conditions of housing and enrichment. The variables included cage size, cage level (upper or lower), enrichment with a foraging log, enrichment with an exercise cage and presence of a mate. The authors first determined the incidence of stereotyped behavior in captive-bred, singly housed adult female and male vervet monkeys. They then exposed monkeys to different housing and enrichment situations and compared the incidence of stereotyped behavior among the monkeys. The authors found that more females than males engaged in stereotyped behavior and that females, on average, engaged in such behavior for longer periods of time than males. Stereotyped behavior was most often associated with a small, single cage. The average amount of observed stereotyped activity in monkeys housed in a small cage was significantly lower when the monkeys had access to either a foraging log or an exercise cage. Stereotyped behavior was also lower in female monkeys that were housed (either with a male or without a male) in a larger cage. The least amount of abnormal behavior was associated with the largest, most complex and enriched housing situation. Males and females housed in cages on the lower level of two-level housing engaged in more stereotyped behavior than did monkeys housed in the upper level, regardless of the presence or type of enrichment provided.

Detection of Mycobacterium kansasii infection in a rhesus macaque (Macaca mulatta) using a modified QuantiFERON-TB Gold assay.

A modification of a highly practical human interferon-gamma release assay for the diagnosis of tuberculosis (TB), the QuantiFERON((R))-TB Gold (In-Tube Method) (QFG-IT) assay, was evaluated for diagnosing natural mycobacterial infection in rhesus macaques (Macaca mulatta). All animals in a captive colony were tested using the QFG-IT and tuberculin skin test (TST). Animals testing positive to these tests were euthanised and necropsied. Selected tissues were processed for histopathology and mycobacterial culture, and positive cultures were speciated by Mycobacterium tuberculosis complex polymerase chain reaction (PCR) and 16S rRNA gene PCR sequencing techniques. M. tuberculosis was cultured from a TST-positive/QFG-IT-positive animal which showed gross pulmonary pathology typical of TB. Additionally, Mycobacterium kansasii was cultured from a TST-negative/QFG-IT-positive animal which had no pathological or histopathological signs of mycobacterial infection. The detection of M. kansasii infection in a QFG-IT-positive animal which showed no evidence of disease indicates that this test might be a highly sensitive tool for the diagnosis of mycobacterial infection in rhesus macaques. However, these findings highlight the limitations of the QFG-IT to specifically detect infection by the pathogens M. tuberculosis and Mycobacterium bovis.

Detection of Mycobacterium tuberculosis infection in chacma baboons (Papio ursinus) using the QuantiFERON-TB gold (in-tube) assay.

BACKGROUND: Early diagnosis of simian tuberculosis (TB) is vital to prevent transmission of this disease. We evaluated the ability of the QuantiFERON-TB Gold (In-Tube Method) assay (QFG-IT) to detect TB in chacma baboons (Papio ursinus). METHODS: Fifty-one baboons were tested using the Tuberculin Skin Test (TST) and the QFG-IT. Baboons testing positive, and animals exposed to infected individuals, were euthanised and subjected to necropsy. Selected tissues were processed for histopathology, mycobacterial culture and genetic speciation. RESULTS: Tuberculosis was confirmed in one TST positive/QFG-IT positive animal and one TST negative/QFG-IT positive animal. One TST positive/QFG-IT negative animal and five TST negative/QFG-IT negative animals were confirmed uninfected following necropsy. CONCLUSION: The QFG-IT correctly detected TB in two baboons, including one TST negative individual and correctly identified six baboons as uninfected, including one TST positive individual. The QFG-IT shows promise as a sensitive, specific test for TB in chacma baboons.

Islet neogenesis is stimulated by brief occlusion of the main pancreatic duct.

OBJECTIVE: Current models of islet neogenesis either cause substantial pancreatic damage or continuously stimulate the pancreas, making these models unsuitable for the study of early events that occur in the neogenic process. We aimed to develop a method where the initial events that culminate in increased pancreatic endocrine mass can be studied. DESIGN AND METHODS: Ten 12-week-old female Wistar rats were subjected to a midline laparotomy, the pancreas was isolated and the main pancreatic duct was occluded for 60 seconds. The pancreas was released and carefully relocated within the abdomen. Ten age-, strain- and sex-matched control rats were subjected to a sham operation. The animals were killed 56 days post occlusion, and the pancreata excised and fixed for histological analysis. Body, pancreatic and hepatic weights were noted at termination and serum was taken for analysis. The endocrine-to-exocrine ratio was calculated and the number of endocrine cells in each islet from the sectioned pancreata was counted. RESULTS: Occlusion of the main pancreatic duct for 60 seconds results in an increase in endocrine mass by 80% 56 days post occlusion. This constitutes an increase in endocrine units (1-6 cells), and in small (7-30 cells), medium (31-60 cells) and large (> 60 cells) islets by 85%, 96%, 95% and 71% respectively. CONCLUSION: Brief occlusion of the main pancreatic duct results in an increase in pancreatic endocrine mass. An increase in endocrine units and small islets is indicative of islet neogenesis. Therefore, owing to the briefness of the stimulation, this model can therefore be used to study the initial events that occur during the neogenic process.