Influence of bovine LH tracer quality on levels of LH in GnRH-treated cows

Modulation of endotoxin-induced andrological alterations by flunixin meglumine in the boar

Flunixin meglumine (FM), an inhibitor of the cyclo-oxygenase pathway of the prostaglandin synthesis, was used to evaluate the andrological changes following an endotoxin (ET) administration in the boar. FM was injected as a single dose 10 min prior to an ET injection. Blood plasma was analysed for the contents of 15-ketodihydroprostaglandin (PG) F2 alpha LH, testosterone and cortisol. Twelve h after the ET administration, the boars were castrated and the testes examined by light and electron microscopy. The results were compared between controls, ET-, FM- and FM+ET-treated boars. An increase in 15-ketodihydro-PGF2 alpha levels was seen following ET administration. Pretreatment with FM decreased the levels of 15-ketodihydro-PGF2 alpha during 2 h. Following the ET administration a voluminous increase in testosterone levels as well as changed LH levels were seen. Similar alterations in hormonal levels were observed also after pretreatment with FM, however, delayed about 2 h, and during this time a marked decrease in testosterone levels was seen. In the testes an infiltration of polymorphonuclear neutrophils (PMN) in the interstitium and histological changes among the Leydig cells were seen after ET injection. Pretreatment with FM reduced the number of invading PMN and the Leydig cells appeared less affected. The results show that FM modulated the negative effects of ET on the testicular function in the boar, indicating that the initiation of the arachidonic acid cascade was of importance for the induction of the alterations following an ET injection.

Radioimmunoassay of bovine, ovine and porcine luteinizing hormone with a monoclonal antibody and a human tracer

A radioimmunoassay for bovine (bLH), ovine (oLH) and porcine (pLH) luteinizing hormone was developed using a human 125ILH tracer from a commercial kit and a monoclonal antibody (518B7) specific for LH but with low species specificity. Standard curves demonstrated similar binding kinetics when bLH, oLH and pLH were incubated with tracer and antibody for 2 h at room temperature. A 30-min delay in the addition of the tracer gave sufficient sensitivity when analysing pLH. Separation of antibody-bound LH from free hormone was achieved by using second antibody-coated micro Sepharose beads. The assay was validated and the performance compared with that of an RIA currently in use for determination of bLH and oLH (coefficient of correlation: 0.99 and 0.98). Regardless of the standards used, intra-assay coefficients of variation were < 10% for LH concentrations exceeding 1 microgram/L. The inter-assay coefficients of variation were < 15%. The assay was used for clinical evaluation demonstrating the pre-ovulatory LH surge in two cyclic cows, LH pulsatility in an oophorectomized ewe and LH response to GnRH injection in a boar.

Alterations in testicular function after endotoxin injection in the boar

Twelve mature boars were injected intravenously with endotoxin from Salmonella typhimurium. Blood plasma was analysed for 15-ketodihydro-PGF2 alpha, LH and testosterone. The boars were castrated at various times after endotoxin administration and the testes examined by light and electron microscopy. The levels of 15-ketodihydro-PGF2 alpha and LH rose immediately after endotoxin injection followed by an increase in testosterone levels, and in five boars a second increase in LH levels was observed. Morphological examination of the testes revealed infiltration of polymorphonuclear neutrophils (PMN) into the testicular interstitium. The Leydig and myoid cells showed morphological changes. Alterations were also present in the seminiferous epithelium among Sertoli cells, spermatocytes and spermatids. The results indicate that endotoxins can exert a negative effect on testicular function in the boar. Except for the initial increase in LH levels, which is not clearly understood, the hormonal changes are thought to be mediated by alterations in Leydig cell function. The alterations further support previous findings in the boar, and indicate that there is short-term, moderate damage to the seminiferous epithelium following endotoxin injection.

Effects on testosterone, LH and cortisol concentrations, and on testicular ultrasonographic appearance of induced testicular degeneration in bulls

It is well known that heat stress has a detrimental effect on testicular functions. In addition to the alteration of semen quality and testicular damage, reproductive hormone secretion can be altered. The objective of this study was to describe changes in plasma concentrations of testosterone, LH and cortisol, as well as in testicular ultrasonographic appearance after induced testicular degeneration. Four Swedish Red and White bulls, aged 3 years, were used. They were fed according to Swedish standards. The scrotum was covered with an insulation device during 96 h. Semen was collected weekly 3 times before and up to 4 months after insulation. Testicular ultrasonography and clinical genital examination were performed with the same intervals. Heparinized blood samples were taken from the jugular vein at 2 h interval during 24 h every 2 weeks during the study. Blood samples were tested for the content of testosterone, LH and cortisol. Data were analysed, using one way analysis of variance of seminal data, clinical examination data as well as 24 h hormonal output data as percentage of mean individual pretreatment values. The use of a 5 MHz B-mode ultrasound unit did not contribute with an objective estimation of the degree of testicular degeneration. In 3 of the bulls testosterone levels had a tendency to decrease and LH to increase during the time of severe degeneration, whereas an opposite trend was seen during the regenerative phase, changes becoming significant 15 weeks after scrotal insulation. Variation between animals was big. Cortisol levels had a decreasing trend, changes being significant only in individual bulls at 10 and 15 weeks after scrotal insulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical, endocrinological and spermatological studies after endotoxin injection in the boar

Three adult boars were injected intravenously with endotoxin from Salmonella typhimurium. Blood plasma was analysed for the contents of 15-ketodihydro-PGF2 alpha, LH and testosterone. Total amount of white blood cells and differential counts were determined in whole blood. Semen was examined for concentration, motility, volume and morphological appearance of the spermatozoa. The boars were slaughtered three months after the endotoxin injection and the testes were examined. The total number of white blood cells decreased and the levels of 15-ketodihydro-PGF2 alpha rose immediately after the endotoxin administration. An initial increase in LH was seen in two out of the three boars. The increase in LH was followed by a testosterone increase in one boar and a testosterone decrease in the other. The third boar showed no initial increase in LH but an increase in testosterone. Semen examination demonstrated various morphological changes of the spermatozoa in all boars. The changes started to appear at about the same time after the endotoxin injection, but differed among the individuals. The examination of the testes depicted no changes from what is seen in normal animals. The present results indicate that the boar responds to endotoxin similar to what is seen in the ram. The endocrine changes, e.g. in LH and testosterone, are similar to those seen after termination of heat stress. The seminal changes indicate a disturbance located in the epididymis as well as a short-term, mild degeneration in the seminiferous epithelium.

Clinical, endocrinological and spermatological studies after endotoxin in the ram

Eight rams were injected intravenously with endotoxin from Salmonella typhimurium. Blood plasma was analysed for the contents of 15-ketodihydro-PGF2 alpha, LH, testosterone, calcium and total amount of white blood cells. Semen was examined for motility, concentration, volume and morphological appearance. After castration at 4 or 16 weeks the testes were examined histologically. The total white blood cells and the calcium levels as well as LH and testosterone decreased and the levels of 15-ketodihydro-PGF2 alpha rose after the endotoxin administration. The examination of the semen showed a significant decrease in motility and a significant increase in abnormal sperm heads. The histological examination showed a slight degeneration in the seminiferous epithelium in the rams castrated at 4 weeks after the endotoxin administration; this degeneration was not seen in the rams castrated at 16 weeks. The present results indicate that endotoxin seems to exert a negative effect on the genital functions of the ram; the changes in LH and testosterone are very similar to those seen after heat induced stress. The histological changes indicate a short-lasting mild degeneration in the seminiferous epithelium.