Fractionation and assay of chicken pituitary hormones

The glycoprotein hormones of the chicken pituitary gland, follicle‐stimulating hormone (FSH), luteinising hormone (LH) and thyroid stimulating hormone (TSH), have been fractionated and partially purified. Fractions were assayed for gonadotrophins using the testicular uptake of ³²P in 1‐d‐old chicks and for thyro‐trophin by chick thyroidal ³²P uptake.     

The biological assay of chicken pituitary gonadotrophins

The properties of gonadotrophins prepared from chicken pituitary glands have been examined by assay methods specific for follicle‐stimulating hormone and luteinising hormone and by two assays which measure the combined effects of these hormones.

Valid parallel line assays were obtained when different preparations of chicken gonadotrophins were compared with standard preparations of human and ovine gonadotrophins. The augmentation and ovarian ascorbic acid depletion assays, which use mice and rats as test animals, were less sensitive to the chicken material than the method which depends on the uptake of ³²P by the testes of 1‐d‐old chicks. It is suggested that this might reflect a species specificity in response.     

Radiotherapy of pituitary tumours in five cats

Five cats tentatively diagnosed with pituitary adenoma (four cases) or pituitary carcinoma (one case), based on computed tomography (CT) or magnetic resonance imaging, were treated with radiotherapy. Electrons were applied in four cats and electrons and photons in the fifth. Ten to 12 fractions of 3.5 to 4.0 Gy each were delivered on a Monday/Wednesday/Friday schedule. The mean total dose applied was 39 Gy. No severe acute side effects to treatment were seen. Follow-up CT examination was performed in four cats; the mass had disappeared in one cat and remained stable or slightly decreased in size in the other three. The survival times were 5.5, 8.0, 15.0, 18.0 and 20.5 months, with two cats dying of causes unrelated to the tumour. Based on these cases, radiotherapy appears to be a valuable treatment option for feline pituitary tumours.     

Outcomes of pituitary tumor irradiation in cats

BACKGROUND: Information on tumor control and normal tissue effects of radiotherapy to treat pituitary tumors in cats is limited. HYPOTHESIS: Radiation therapy is effective in controlling the clinical signs associated with pituitary tumors in cats, with a low incidence of adverse effects. ANIMALS: Eight cats were irradiated at Colorado State University between 1991 and 2002 for spontaneous pituitary tumors. METHODS: A retrospective review of records was made to assess tumor control and incidence of radiation-induced adverse effects. RESULTS: Pituitary carcinoma was diagnosed in 2 cats and pituitary adenoma in 6 cats. Total radiation dosage ranged from 4,500 to 5,400 cGy administered Monday through Friday in 270 or 300 cGy fractions. Acute effects were limited to epilation and mild otitis externa. Focal brain necrosis adjacent to regrowth of a pituitary carcinoma and a second tumor in the radiation field were reported as possible late effects. Median survival, regardless of cause of death of the 8 cats, was 17.4 months (range, 8.4 to 63.1 months). Median survival could not be determined if cats were censored for non-tumor-related causes of death. Six cats were alive at 1 year, and 3 cats were alive at 2 years after treatment. Tumor recurrence was seen in 1 cat with a pituitary carcinoma. Neurologic signs improved within 2 months in all 5 cats that presented with abnormal neurologic signs. Clinical signs caused by a concurrent endocrine disorder began to improve within 1-5 months in the 7 cats with hyperadrenocorticism or acromegaly. CONCLUSIONS AND CLINICAL RELEVANCE: Radiation therapy is an effective primary treatment modality for cats presenting with neurologic signs associated with a pituitary mass and can improve clinical signs associated with concurrent hyperadrenocorticism or acromegaly in cats with no neurologic abnormalities.     

Effects of pituitary stalk-transection and type of barrier on pituitary and luteal function during the estrous cycle of the ewe

Effects of pituitary stalk-transection on plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) prolactin (PRL) and progesterone were investigated during the estrous cycle of ewes. Pituitary stalk (SS) or sham (SH) transection was performed on day 1 (estrus = day 0) of the estrous cycle. A Teflon or Silastic barrier was placed between the cut ends of the stalk to prevent reorganization of the portal vasculature. Immediately following surgery, pulsatile administration of gonadotropin releasing hormone (GnRH, 200 ng/hr) or .9% NaCl was initiated and continued for the duration of the experiment. Estradiol benzoate (EB, 50 μg im) was administered to all ewes on day 3. Mean concentrations of LH were greater in SS ewes than in SH ewes (P<.05). There was a trend (P=.06) for the concentration of LH to be higher in ewes with Teflon compared with Silastic barriers between the cut ends of the stalk. Infusion of GnRH elevated concentrations of LH in both SS and SH ewes (P<.05). Concentrations of progesterone were reduced (P<.01) in saline-infused SS ewes while infusion of GnRH in SS ewes maintained concentrations of progesterone similar to saline-infused SH ewes. The concentrations of FSH or PRL were unaffected by SS, type of barrier or treatment with GnRH. Administration of EB failed to induce a surge of LH except in a SH ewe infused with GnRH. Ewes were more responsive to infusion of GnRH following SS than after SH as reflected by increased plasma concentrations of LH and progesterone.     

The anterior pituitary gland: lessons from livestock

There has been extensive research of the anterior pituitary gland of livestock and poultry due to the economic (agricultural) importance of physiological processes controlled by it including reproduction, growth, lactation and stress. Moreover, farm animals can be biomedical models or useful in evolutionary/ecological research. There are for multiple sites of control of the secretion of anterior pituitary hormones. These include the potential for independent control of proliferation, differentiation, de-differentiation and/or inter-conversion cell death, expression and translation, post-translational modification (potentially generating multiple isoforms with potentially different biological activities), release with or without a specific binding protein and intra-cellular catabolism (proteolysis) of pituitary hormones. Multiple hypothalamic hypophysiotropic peptides (which may also be produced peripherally, e.g. ghrelin) influence the secretion of the anterior pituitary hormones. There is also feedback for hormones from the target endocrine glands. These control mechanisms show broadly a consistency across species and life stages; however, there are some marked differences. Examples from growth hormone, prolactin, follicle stimulating hormone and luteinizing hormone will be considered. In addition, attention will be focused on areas that have been neglected including the role of stellate cells, multiple sub-types of the major adenohypophyseal cells, functional zonation within the anterior pituitary and the role of multiple secretagogues for single hormones.     

Radiation therapy in two cats with pituitary tumors

Two cats with large pituitary neoplasms (adenoma and adenocarcinoma) were treated with fractionated radiation therapy. Total doses of 40 Gy, respectively 36 Gy, were applied in 10 fractions of 4 Gy, and 3.6 Gy respectively. Side effects were minimal and transient. Anesthesia was well tolerated. Improvement of clinical signs could be observed during radiation therapy in both cats. One cat had a complete, the other a partial tumor response. One cat (suspicion of adenoma) was euthanized 1 3/4 years after therapy due to unrelated disease. No tumor was found on histopathology, however a small focal necrosis of brain tissue in the irradiated field was observed. The second animal with a pituitary adenocarcinoma was euthanized because of tumor recurrence 1 1/2 years after therapy. Radiation therapy was effective, despite the low total doses of radiation applied.     

Correlation of pituitary histomorphometry with adrenocorticotrophic hormone response to domperidone administration in the diagnosis of equine pituitary pars intermedia dysfunction

Functional evaluation of the pars intermedia (PI) is required for the early diagnosis of equine pituitary PI dysfunction (PPID), yet most assays target the hypothalamic-pituitary-adrenal axis, which regulates the pars anterior. In contrast, the PI is regulated by dopaminergic tone from hypothalamic neurons. Loss of dopaminergic inhibition is hypothesized to cause the PI hypertrophy and hyperplasia that result in the clinical manifestations of PPID. Domperidone, a dopamine receptor antagonist, should exacerbate the loss of dopaminergic inhibition in horses with PPID and increase the release of endogenous adrenocorticotrophic hormone (eACTH) by PI melanotrophs. To test this, plasma eACTH concentration was determined in horses with or without clinical signs of PPID at 0, 4, and 8 hours after oral administration of 3.3 mg domperidone/kg. Pituitary glands were evaluated postmortem by histologic grading and morphometry. In the 33 horses, median age, plasma ACTH concentration 8 hours after domperidone, and PI area in median sagittal sections were associated with histologic grade as follows: pituitary grade 1 (normal), n = 3, 7.5 years, 20.0 pg/ml, 0.16 cm(2); grade 2 (focal hypertrophy or hyperplasia), n = 9, 14.5 years, 27.1 pg/ml, 0.27 cm(2); grade 3 (diffuse adenomatous hyperplasia), n = 5, 21.0 years, 64.4 pg/ml, 0.48 cm(2); grade 4 (microadenomas), n = 12, 23.3 years, 128.0 pg/ml, 0.87 cm(2); grade 5 (adenoma), n = 4, 24.9 years, 720.5 pg/ml, 2.1 cm(2). Results suggest that horses with pituitary histologic grade > or =3 respond to domperidone with increased plasma ACTH concentration.     

Clinical presentation of pituitary adenomas in rats.

This article describes the clinical presentation of central vestibular disease secondary to pituitary adenoma as it manifested in six rats. Prognosis is poor. Recommendations are made regarding questions to ask and advice to offer owners when dealing with cases.     

Suspected pituitary apoplexy in a German shorthaired pointer

Pituitary apoplexy is a syndrome which has been described in humans caused by acute haemorrhage or infarction within a pituitary tumour or a non-tumorous pituitary gland. This report describes the authors' observations of a dog in which vomiting, visual disturbances, seizures, altered consciousness and diencephalic dysfunction occurred in association with haemorrhage originating from a pituitary macroadenoma. The clinical signs were thought to be consistent with disruption of the hypothalamus and brainstem, together with raised intracranial pressure due to intraventricular haemorrhage. These signs, and the pathological findings, bear a striking resemblance to those associated with the syndrome of pituitary apoplexy, seen in humans.     

垂体腺苷酸环化酶激活多肽(PACAP)的研究概况

垂体腺苷酸环化酶激活多肽(PACAP)属于促胰液素胰高血糖素/VIP家族的新成员,最初发现其对大鼠垂体细胞腺苷酸环化酶(AC)具有高激活作用。随着研究的深入,发现其具有多种生物功能,文中就其影响动物对营养物质的消化,动物的繁殖性能,动物的能量平衡和动物的免疫系统等做简要概述。     

Imaging diagnosis: pituitary apoplexy in a cat

A 7-year-old male neutered domestic short-haired cat had depression for 5 months and acute blindness. A lesion at the level of the rostral and middle cranial fossae was suspected. A large pituitary mass compressing the optic chiasm was detected in magnetic resonance images and there was also evidence of recent intratumoral hemorrhage, leading to a diagnosis of pituitary apoplexy; these findings were confirmed at postmortem examination. Pituitary apoplexy is a clinical syndrome characterized by acute neurologic signs related to hemorrhagic infarction within a pituitary tumor. Pituitary apoplexy should be considered in patients with acute onset of blindness and altered mental status.