Hm Mutembei

Canine prostaglandin E2 synthase (PGES) and its receptors (EP2 and EP4): Expression in the corpus luteum during dioestrus

In the dog CL are the only source of the progesterone in cyclic and pregnant animals. From a high expression of cyclooxygenase 2 (Cox2) at the beginning of the dioestrus and a low one at the end it was suggested that prostanoids may play a role in the formation of the CL. This led to the hypothesis that also in the dog PGE2 of luteal origin might act as paracrine/autocrine factor. Hence, expression of the prostaglandin E2 synthase (PGES) and its receptors (EP2 and EP4) was determined during the course of dioestrus in canine CL from days 5, 15, 25, 35, 45, 65 after ovulation, following cloning of PGES using SMART RACE PCR, which revealed a high homology (82-94%) with other species. Real Time (TaqMan) PCR showed a high PGES and EP2 expression in the early CL-phase with a significant decrease thereafter. EP4 revealed a constant expression pattern throughout the life span of the CL. In situ hybridization co-localized PGES, EP2 and EP4 in the cytoplasm of the luteal cells only. In conclusion, our data suggest that in the dog PGE2 of luteal origin acts by autocrine mechanism as a luteotropic factor through its EP2 and EP4 receptors during the phase of CL-formation.

Testicular steroid hormone secretion in the boar and expression of testicular and epididymal steroid sulphatase and estrogen sulphotransferase activity.

BACKGROUND Spermatogenesis and epididymal function depend on testicular steroids with estrogens being important regulatory factors. However, testicular estrogen secretion shows distinct species specificities, with the boar being characterized by the production of high amounts of estrone [E1] and estronesulphate [E1S]. As the boar testis also expresses estrogen sulphatase [StS] and sulphotransferase [EST] the present paper is based on the hypothesis that local availability of biologically active estrogens results from an interplay between estrogen synthesis and local activities of StS and EST. METHODS Blood was collected during castration of 37 boars, aged between 98 (peripubertal) to 2 793 (old sexually mature) days, from the testicular vein and artery and peripheral circulation; E1, E1S, testosterone [T] and progesterone [P] were determined by established RIA-procedures. Similarly seminal plasma from 21 sexually mature boars was assessed. StS- and EST-activity were determined in testicular- and epididymal homogenates of 3 sexually mature boars (200 d) using (3)H-E1S resp. (3)H-E1 as substrate. Immunohistochemistry [IHC] was applied to locate EST- expressing cells in testes in relation to age and in the epididymis of 3 mature boars. RESULTS Hormone data showed a high variability. A significant age dependent increase was only observed for E1 and E1S in the peripheral circulation with absolute values being highest for E1S (5-60 nmol/l), followed by T (2.6-14 nmol/l), P (0.5-1.48 nmol/l) and E1 (0.24-0.84 nmol/l). Testicular vein concentrations always exceeded those in the testicular artery with the differences being significant for E1 and P, group 1. Concentrations in the testicular artery and peripheral vein plasma were not different but higher (p<0.0001) than those in seminal plasma with the exception of E1. StS activity was higher (p<0.001) in the testis than the epididymis. EST activity was high in epididymal homogenates and at the level of detection in testis homogenates. IHC located EST in virtually all epididymal epithelial cells. In the testis the number of positive staining Leydig cells decreased (p<0.05) from 72% in the premature to 57% in the mature boars. CONCLUSION The provision of biologically active estrogens to the testicular and epididymal compartment is controlled by a complex regulatory system, with the sulphatase pathway being an important component. P is a secretory product of the testis, E1 and E1S are not actively enriched in seminal plasma.

Expression and activity of steroid sulphatase in the boar testis

Oestrogens are essential for male fertility targeting the testicular-epididymal compartment. However, the underlying mechanisms are only vaguely known and species specificities must be considered. The boar has a remarkably high testicular-oestrogen output, with the biologically inactive oestrone-sulphate being the major oestrogen occurring in the testicular vein. In the boar testis and epididymis, activity of steroid sulphatase (StS) and oestrogen sulphotransferase has been demonstrated. Thus apart from their synthesis in Leydig cells, provision of biologically active free oestrone seems also to depend on the activity and localization of these enzymes. Our aim was to establish expression patterns and activity of StS in boar testis. Testes were randomly collected from healthy boars and allotted to five age groups, five animals in each, aged 50, 100, 150, 200 and 250 days. Three extra boars aged over 250 days were castrated to obtain fresh tissue for enzyme activity tests. Immunohistochemistry detected StS only in the cytoplasm of Leydig cells and - except for day-50 group in which 65.1 +/- 4.9% (X +/- SD) of the cells were positive - expression was constant with virtually all the cells staining positive. RT-PCR and in situ hybridization confirmed expression and localization of StS mRNA. The V(max) and K(m) value (X +/- SD) for StS was 24.05 +/- 0.3 fmol/s/microg protein and 2.15 +/- 0.12 microM. These data suggest that StS within the Leydig cells of the boar is involved in modulation of testicular oestrogen bioavailability and that the site of sulpho-conjugation is not the testis but a different compartment of the testes-epididymidis complex.

Anthelmintic administration to small ruminants in emergency drought responses: assessing the impact in two locations of northern Kenya

Internal parasites are a significant determinant of the productivity of ruminant species in the tropics. Provision of anthelmintics has become a predominant part of animal health interventions in emergency drought responses, aiming to maintain the food conversion efficiency of livestock when pasture is scarce. This study aimed to assess the owner-perceived impact of anthelmintic provision on the health and productivity of small ruminants in the drought-prone counties of Isiolo and Marsabit, northern Kenya. Participatory approaches were used to retrospectively measure differences in key indicators of livestock output before and after anthelmintic administration. Results showed that there was no perceived impact of anthelmintic administration during droughts on small ruminant health and productivity, but some benefit of anthelmintic administration during rainy season was perceived. The study also provided some evidence of potential differences in the epidemiology of internal parasites between the counties. These findings may be utilised to inform future livestock intervention programmes in drought-prone areas.

Knowledge and practices of the residents living along the Nairobi river riparian on the use of the contaminated river for farming and its effects on animal reproduction

Residents practising pig farming along the Nairobi River Riparian in Kenyawere interviewed to evaluate theirknowledge and practices on the use of the contaminated riverfor farming and its effects on animal reproduction. Eighty (80) farms were purposively selected and questionnaires administered to the pig owners as respondents.Majority (72.5%) were involved in urban farming as supplementary source of income while the rest had farming as their main occupation. Over a third of them (38.8%) had attained secondary level of education. Over forty percent (42.5%, N=34) respondents used the contaminated river for pig farming. The main reason cited for the use of the river water for farming were that it is a free source and readily available (N=20).The main reproductive effect noted on the male pigs was abdominally testes. The reproductive defect points towards environmental estrogen toxicant within the water of the Nairobi riversuggesting the residents need to be made aware of the potential danger of the use of the contaminated water for farming.