| Records |
| Author |
Malmgren, L.; Andresen, Ø.; Dalin, A.-M. |
| Title |
Effect of GnRH immunisation on hormonal levels, sexual behaviour, semen quality and testicular morphology in mature stallions |
Type |
Journal Article |
| Year |
2001 |
Publication |
Equine Veterinary Journal |
Abbreviated Journal |
Equine vet. J. |
| Volume |
33 |
Issue |
1 |
Pages |
75-83 |
| Keywords |
horse; GnRH; immunisation; stallion; testosterone; oestrone sulphate; sexual behaviour; semen quality |
| Abstract |
Summary The aim of this study was to investigate the effect of gonadotrophin-releasing hormone (GnRH) immunisation on mature stallions that had been used for breeding. Four Standardbred stallions were used in the study: 3 experimental animals and 1 control animal. Semen was collected regularly, i.e. twice/week, during the 4 months prior to the experimental period. The stallions were immunised against GnRH with a GnRH-BSA conjugate. Equimune was used as the adjuvant. The stallions were immunised on 5 occasions, 4 at 2 week intervals, and the fifth 4 weeks after the fourth. Blood samples were taken once a week for analysis of GnRH antibody titre and every third week for testosterone and oestrone sulphate analyses. Semen was collected once a week, and libido and sexual behaviour were observed. Ejaculate volume, sperm concentration, total number of sperm in the ejaculate, sperm motility and sperm morphology were evaluated. Testicular size was measured once a week. At the end of the study, the stallions were castrated, and a histological examination of the testes performed. All immunised stallions produced antibodies against GnRH, and plasma testosterone concentration decreased. However, the effect of immunisation varied between stallions. In 2 of the stallions, high levels of antibodies were found, while in the third, the level was moderate. Four weeks after the first immunisation, a decrease in libido was observed. Two months after the first immunisation, marked changes in semen quality were observed in the 2 stallions with high antibody titres. Fourteen weeks after the first immunisation, the total number of sperm/ejaculate had decreased from >8.6×109 to<2.7×109, sperm motility from >59 to<10% and the frequency of morphological normal spermatozoa had decreased from >60 to<14%. The dominating abnormalities were abnormal head shapes, proximal cytoplasmic droplets and detached heads. In the third stallion, only slight changes in semen quality were found. No changes were observed in the control stallion. Decreases in testicular size were noted in all of the experimental stallions. Pronounced histological alterations in the testes were observed in 2 of the stallions. It is concluded that the vaccine was effective in stimulating production of GnRH antibodies and in suppressing testicular function and androgen secretion. However, there was an individual variation in the responses among the stallions and, further, libido was not totally suppressed. |
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Blackwell Publishing Ltd |
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| ISSN |
2042-3306 |
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Equine Behaviour @ team @ |
Serial |
5312 |
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| Author |
Andrew, R.J. |
| Title |
Changes in visual responsiveness following intercollicular lesions and their effects on avoidance and attack |
Type |
Journal Article |
| Year |
1974 |
Publication |
Brain, Behavior and Evolution |
Abbreviated Journal |
Brain Behav Evol |
| Volume |
10 |
Issue |
4-5 |
Pages |
400-424 |
| Keywords |
Animals; Chickens; Humans; Male; Mutism; Superior Colliculi/*physiology; Tectum Mesencephali; Testosterone; Visual Fields; Vocalization, Animal |
| Abstract |
In the normal chick, conspicuous visual stimuli induce targetting and pecking together, with vocalization. All three are abolished by lesion of the intercollicular area (ICo) or of connections passing through its medial margin. After such lesions, chicks also cease to treat significant visual stimuli as if they were startling and exciting, and may delay response as a result. However, they are still able to recognise, orient accurately to, and respond appropriately to, a variety of complex visual stimuli (e.g. food grains, copulation object). In addition, they are little affected by strange surroundings. Lesion evidence suggests the mammalian subcollicular area to have similar functions to the ICo and to be homologous with it. A route (present in bird), which is well-known in mammals for its association with threat, defense and escape evoked by strange and frightening objects (amygdala-diencephalic periventricular system-central mesencephalic grey, A-DPS-CMG) is stimuli via the 2 ICo (subcollicular area). Two different mechanisms may be involved caudal to the ICo. One consists of tectal afferents which might modulate the evocation of targetting, pecking and other responses via the tectum. The other is the predorsal system of tectal efferents which may mediate such responses. Classical syndromes of tameness and unresponsiveness produced by various interruptions of the A-DPS-CMG route may depend on interruption of connections to these midbrain mechanisms. Attack is depressed by ICo lesions as one aspect of reduced responsiveness to conspicuous and startling visual stimuli. Avoidance, which is apparently mediated by a separate system, much as in Anura, is facilitated. |
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English |
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0006-8977 |
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| Notes |
PMID:1169102 |
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no |
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Equine Behaviour @ team @ |
Serial |
4626 |
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| Author |
Chaudhuri, M.; Ginsberg, J.R. |
| Title |
Urinary androgen concentrations and social status in two species of free ranging zebra (Equus burchelli and E. grevyi). |
Type |
Journal Article |
| Year |
1990 |
Publication |
Journal of Reproduction and Fertility |
Abbreviated Journal |
J Reprod Fert |
| Volume |
88 |
Issue |
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Pages |
127-133 |
| Keywords |
zebra; testosterone; androgens; territoriality; social behaviour; dominance |
| Abstract |
In both species of zebra, breeding males had higher urinary androgen concentrations (ng androgens/mg Cr) than did non-breeding bachelor males (30.0 +/- 5.0 (N = 9) versus 11.4 +/- 2.8, (N = 7) in the plains zebra; 19.0 +/- 2.2 (N = 17) versus 10.7 +/- 1.2 (N = 14) in the Grevy's zebra). In the more stable family structure of the plains zebra (single male non-territorial groups) variations in androgen concentrations could not be ascribed to any measured variable. In the Grevy's zebra, androgen values were significantly lower in samples taken from territorial (breeding) males which had temporarily abandoned their territories (N = 4) and the urinary androgen concentration for a male on his territory was negatively correlated with the time since females last visited the territory. |
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| Notes |
from Professor Hans Klingels Equine Reference List |
Approved |
yes |
| Call Number |
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Serial |
987 |
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