Encephalic Ventricles of the Ewe (&lt;i&gt;Ovis aries&lt;/i&gt;L.): Conformation, Relations and Stereotaxic Topography

Lignereux, Y.; Regodón, S.; Marty, M.; Franco, A; Bubien, A.

doi:10.1159/000147103

Cited by 6 publications

(8 citation statements)

References 3 publications

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“…UK) was injected into the brain ventricles and X-ray photographs using a Polaroid instant film (Polaroid, Cam bridge. Mass.. USA) were used to visualise the infundibular recess in the base of the third ventricle [22], The micro-implants were intro duced through bilateral 18-gauge guide cannulae placed 2 mm from the midline and fixed to the skull. Where the animals received a sin gle pair of implants (sham C -half of group.…”

Section: Micro-implants and Surgerymentioning

confidence: 99%

Does Melatonin Act on Dopaminergic Pathways in the Mediobasal Hypothalamus to Mediate Effects of Photoperiod on Prolactin Secretion in the Ram?

Lincoln

Tortonese²

1995

Neuroendocrinology

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Previous studies have shown that the chronic administration of melatonin in the mediobasal hypothalamus (MBH) using micro-implants in Soay rams housed under long days causes a sustained decrease in the secretion of prolactin as occurs in response to short days. The purpose of this study was to investigate whether hypothalamic dopaminergic (DA) systems acting through D₂ receptors may be involved in this melatonin-induced effect. Groups of Soay rams living under long days were treated in the MBH with micro-implants containing bromocriptine (BROM, DA D₂ receptor agonist), or sulpiride (SULP, DA D₂ receptor antagonist), given alone or in combination with melatonin (MEL), to establish whether the DA drugs would mimic or negate the effects of melatonin. A control group (C) received empty micro-implants or no treatment. The micro-implants were bilateral and were left in place for 14 weeks; the trial continued for a total of 28 weeks (14-week implant period and 14-week post-implant period) while the animals remained under long days. The ability of the micro-implants to release BROM and SULP for 14 weeks was confirmed by incubating implants in vitro and testing for the presence of the compounds using a pituitary cell bioassay. MEL in the MBH induced a marked decrease in the blood plasma concentrations of prolactin during the implant period and an increase during the postimplant period (MEL vs. C, p < 0.001). BROM given alone induced a sustained decrease in the plasma concentrations of prolactin (less marked than MEL), while SULP caused an increase (BROM and SULP vs. C, p < 0.001); the effects were restricted to the implant period. BROM given in combination with MEL produced the same effect as MEL alone during both the implant and postimplant periods, while SULP given with MEL produced the same effect as MEL during the implant period, but impaired the increase in plasma concentrations of prolactin during the postimplant period (MEL + SULP vs. MEL, p < 0.001). There were changes in growth and moulting of the pelage correlated with the marked changes in the secretion of prolactin induced by MEL, but not related to the lesser effects of BROM and SULP. In conclusion, the long-term effects of the D₂ agonist and antagonist are consistent with the inhibitory role of hypothalamic DA pathways in the homeostatic regulation of prolactin secretion. The inhibitory effect of the D₂ agonist did not mimic that of MEL in the MBH, thus it is unlikely that the short day MEL signal operates primarily through a hypothalamic DA system to inhibit the secretion of prolactin. However, since the administration of the D₂ antagonist in the MBH did influence the response to MEL, it is probable that DA pathways are involved in relaying the effects of MEL on the long-term cycle in the secretion of prolactin in the ram.

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Section: Micro-implants and Surgerymentioning

confidence: 99%

Does Melatonin Act on Dopaminergic Pathways in the Mediobasal Hypothalamus to Mediate Effects of Photoperiod on Prolactin Secretion in the Ram?

Lincoln

Tortonese²

1995

Neuroendocrinology

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“…In our study, it was also not found in the ventricular casts and MRI images of Akkaraman sheep. Lignereux et al (1991) No information was found in the literature about the size of the interventricular foramen (foramen of Monro) in dissected sheep brains. In our study of Akkaraman sheep, it was determined that there was a flat oval port 1.4 × 3.9 mm wide and 5.5 mm long.…”

Section: Discussionmentioning

confidence: 99%

An anatomical and volumetric study on brain ventricles in sheep using different techniques

Kose

Düzler

2023

Anat Histol Embryol

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This study investigated the morphological features of the ventricular system of the brain in Akkaraman sheep in a measured and structural manner. In the study, 24 adults male Akkaraman sheep, which is a common and hornless breed were used. Anatomical features of the ventricular system were determined by latex injection and dissection, acrylic injection and corrosion cast and magnetic resonance imaging. In the measurements, a precise digital calliper, Archimedes' principle, Cavalieri's principle and ITK‐SNAP imaging were used by comparing them with each other. The average weight of fresh sheep brains was 102 g (0.226 lb), the volume 115.8 mL and the length, height and width were 130.78, 40.58 and 70.08 mm, respectively. The olfactoric bulb contained a cavity associated with the lateral ventricle, large enough to be called a ventricle. The cavity of septum pellucidum has a large cavity was observed. However, there was no cerebrospinal fluid in this cavity. The interventricular foramen of the dissected brain was also an opening measuring 1.4 mm × 3.9 mm × 5.5 mm. The total volume of the ventricles of the brain of Akkaraman sheep was found to be 7107.71 ± 479, 7115 ± 737 and 7080 ± 647 mm3 and 6200 mm3 using the Planimetry, Point Counting method, ITK‐SNAP program, and Archimedes' principle, respectively. In the study, species and breed‐specific brain indices values and many detailed morphometric data were obtained.

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“…Briefly, anoestrous Suffolk ewes (2-3 years old, 35-45 kg) were anaesthetised and a stereotaxic frame was set up. A burr-hole was made in the skull anterior to the bregma, and the location of the pituitary gland was deduced from lateral skull radiographs after instillation of radio-opaque dye into the cerebral spinal fluid to visualise the third ventricle (Mori et al 1990, Lignereux et al 1991. For injection of virus particles or of saline control, a fine-bore metal cannula was inserted stereotaxically and lowered to the base of the pituitary fossa.…”

Section: Animals and Stereotaxic Pituitary Injectionmentioning

confidence: 99%

Adenovirus-mediated gene transfer in the ovine pituitary gland is associated with hypophysitis

Davis

Mcmahon

Löwenstein

et al. 2002

Journal of Endocrinology

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Gene therapy for pituitary disease requires evaluation for safety as well as efficacy. We have reported results of adenovirus-mediated gene transfer using the sheep as a large animal model that allows longitudinal evaluation of hormone secretion and have confirmed high levels of transgene expression up to 7 days after direct stereotaxic injection into the pituitary gland. Here we report the results of detailed histological examination of the pituitary glands from animals injected with two recombinant adenoviruses expressing the beta-galactosidase marker gene, or with saline vehicle to control for the potential tissue-disruptive effect of the injection volume itself. Pituitaries injected with saline showed no evidence of inflammatory response apart from occasional minor foci of apoptosis. In all other respects they were indistinguishable from normal uninjected control pituitary glands. Glands injected with recombinant adenoviruses containing either the hCMV-beta-gal or the hPRL-beta-gal transgene, on the other hand, displayed variable degrees of inflammatory response, with periglandular fibrosis, lymphocytic infiltrate and venulitis in almost all cases. Focal necrosis and/or apoptosis was noted in six of nine cases. In summary, we have found evidence of severe inflammatory reaction within the first seven days of adenovirus injection, amounting to significant hypophysitis. The histological extent of this reaction has not previously been recognised by studies of the efficacy of gene transfer in rodents, and was underestimated by immunocytochemical studies of hormone and transgene expression. The findings emphasise the need for careful evaluation of the safety of endocrine gene therapy, and for caution with the dose of vector used.

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Encephalic Ventricles of the Ewe (<i>Ovis aries</i>L.): Conformation, Relations and Stereotaxic Topography

Abstract: Fifteen ewes, aged 3–6 years, were used for studying the conformation of the cerebral ventricles on mouldings, and the topography on scannographs and frozen cuts. The lateral ventricles show important variations, but the topography of their olfactory recess is constant.

Cited by 6 publications

References 3 publications

Does Melatonin Act on Dopaminergic Pathways in the Mediobasal Hypothalamus to Mediate Effects of Photoperiod on Prolactin Secretion in the Ram?

Does Melatonin Act on Dopaminergic Pathways in the Mediobasal Hypothalamus to Mediate Effects of Photoperiod on Prolactin Secretion in the Ram?

An anatomical and volumetric study on brain ventricles in sheep using different techniques

Adenovirus-mediated gene transfer in the ovine pituitary gland is associated with hypophysitis

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