Pulmonary intravascular macrophages (PIMs) promote lung inflammation and are found in ruminants, horses, pigs, cats, and dolphins, but not in primates, rats and mice. Rabbits are used to study mechanisms of lung inflammation in humans, but disagreement exists whether rabbits have PIMs. This study examined rabbits for PIMs, and their influence on endotoxin-induced lung inflammation.<p> Rabbits were treated with gadolinium chloride (10 mg/kg intravenous: Group GC, n=6) to produce apoptosis in PIMs, or with saline (Group SAL, n=6). Rabbits were euthanized 48 hours later. Light microscopic examination of epoxy-embedded rabbit lung sections revealed mononuclear phagocytes in alveolar septa. Transmission electron microscopy confirmed PIMs with lysosomes and close attachment to capillary endothelium. Light microscopic immuno-cytochemistry using rabbit anti-macrophage antibody (RAM-11) showed staining of septal and alveolar macrophages. There was no difference in number of RAM-11 positive septal cells between SAL and GC rabbits (P=0.2).<p> Rabbits were administered intravenous E.coli 0127:B8 endotoxin (100 Ýg/kg) 48 hours after GC (GC-LPS; n=5) or SAL treatment (SAL-LPS; n=6), and euthanized 24 hours later. Rabbits in both LPS treated groups were hypocalcaemic and exhibited compensated metabolic acidosis compared to SAL rabbits. Four rabbits died in the SAL-LPS group within 24 hours of the endotoxin treatment and were replaced. None died in the GC-LPS group (Chi-square comparison for survival P=0.063). Greater numbers of septal heterophils were found in groups SAL-LPS and GC-LPS compared to SAL and GC. TNFÑ protein in serum, and IL-1Ò and IL-6 mRNA in lung tissues were increased in SAL-LPS compared to SAL and GC rabbits. Lung tissues from SAL-LPS rabbits but not in GC-LPS showed moderate inflammation, but lung wet/dry ratios were not different. Lung tissue TNFÑ, IL-1Ònand IL-6 mRNA, myeloperoxidase activity, and serum TNFÑ were reduced in GC-LPS animals compared to SAL-LPS. Immuno-electron microscopy revealed TNFÑ in PIMs in normal and LPS-treated rabbits. Lung and liver tissue TNFÑ, IL-8 and MCP-1 protein concentrations were not different between groups. GC did not appear to reduce liver inflammation. These data show that rabbits have low numbers of PIMs. GC treatment induced apoptosis in PIMs and reduced endotoxin-induced lung inflammation and mortality.

This study tested the hypothesis that a plant compound, 6-methoxybenzoxazoline (6-MBOA), can affect the annual reproductive cycle of wild rabits by acting as an agonist or antagonist of melatonin. Preliminary investigations into seasonal changes in the reproductive endocrinology of wild-caught adult female rabbits kept in outdoor cages revealed an annual cycle of pituitary (release of LH) and ovarian (release of progesterone) responses to exogenous GnRH. The largest responses were between March and May (during the peak breeding season in the wild), followed by a decrease in July. Pituitary responsiveness returned by late November, whereas ovarian responsiveness did not increase until after the winter solstice. Studies of the responses to GnRH of adult female rabbits kept indoors under regulated photoperiod demonstrated that the decrease in pituitary and ovarian responsiveness in July was due to declining daylength. Seasonal regrowth of the reproductive system at the winter solstice was stimulated by transfer to `long days' (16L:8D). This stimulation by long days was not observed if rabbits were also treated with daily, timed intra-muscular (i.m.) injections of melatonin, but injections of 6-MBOA were ineffective. Daily, timed injections of 6-MBOA did not stimulate the reproductive system of seasonally-anoestrus adult female rabbits in the autumn. Treatment of adult female rabbits with sub-cutaneous (s.c.) implants of 6-MBOA failed to prevent a decrease in pituitary and ovarian responsiveness to GnRH on transfer to `short days' (8L:16D). Sexually mature male rabbits under long days received daily, timed i.m. injections of 6-MBOA or melatonin. Only those treated with melatonin showed testicular regression. A dose-response relationship for 6-MBOA was tested by treating adult male rabbits with 6-MBOA in different size s.c. implants. All sizes tested failed to induce testicular regression. No evidence was found that 6-MBOA can affect the annual reproductive cycle in wild rabbits by acting as an agonist or antagonist of melatonin.

No description available.

Thesis (M.S.) in Wildlife Ecology--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 145-164).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. Includes bibliographical references.

No description available.

Two populations of rabbits (Oryctolaqus cuniculus) were investigated to see whether polygynous, multi-male groups formed in the absence of large multi-entranced warrens. They did not. Rabbits neither gathered in space nor time. The small warrens were spread out evenly across homogeneous patches and the females were well spaced out. Monogamy, distinguished by a battery of tests, was prevalent, with the more dominant males as 'mate' rabbits. That the polygyny frequently mentioned in the literature was a result of male dominance and female defense was considered. The genetic structure of each population was investigated by taking blood from rabbits and having it analysed electrophoretically and for immunoglobulins. A method for assessing relatedness between groups of pairs of animals was implemented, then validated and developed with Monte Carlo simulations. With the seven polymorphic allele obtained, no non-zero relatedness was found but it was sometimes possible to exclude high relatedness. The bearing of sociality on vigilance during feeding was investigated. Although a rabbit's vigilance decreased as its 'mate' approached, the presence of other rabbits was correlated with increased vigilance. It was concluded that the need for social vigilance outweighed the benefit of 'many eyes' watching for predators. This conclusion was tested by experiment, using stuffed animals as stimuli. Rabbits increased their vigilance during grazing bouts both by increasing the length and frequency of scans. Scans could be short or long: the probability of ending a scan decreased sharply at a certain point; a form of positive feedback. The durations of short 'maintenance' scans were dependent on chewlength (the amount of food in the mouth). This fitted a timesharing definition as supported by experiment. Long scans in response to a visible threat did not involve chewing.

No description available.

<p> Electrical stimulation of areas in the diencephalon and central grey of the conscious rabbit produces a response of thumping the ground with the hindfeet. The response is not elicitable from the neocortex, striatum or internal capsule. Thumping movements occur mainly after offset of the eliciting stimulus and the likelihood of a response decreases regularly with time, suggesting the decay of a central excitatory state.</p> <p> Central stimulation which produces thumping behaviour tends to be aversive in tests for self-stimulation. Further, the behaviour can be elicited by peripheral electric shock. Therefore thumping behaviour may be a sign of fear in the rabbit.</p> / Thesis / Master of Arts (MA)

A novel in stories.