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At least 145 records · Page 8Linked to original sources
PubMed1984

Neurotransmitter effects on in vitro prolactin and growth hormone release from fowl pituitary glands: dopamine and noradrenaline.

Pituitary glands and hypothalami from broiler fowl heads were incubated alone or together with dopamine, noradrenaline or monoaminergic drugs (apomorphine, pimozide, phentolamine, isoproterenol and propranolol). The basal release of both prolactin and growth hormone was not affected by any of these amines or aminergic drugs. The co-incubation of pituitary glands with whole hypothalami consistently stimulated prolactin and growth hormone secretion. Apomorphine inhibited hypothalamus-induced prolactin and growth hormone release and the response was blocked by pimozide. Noradrenaline markedly stimulated hypothalamus-induced prolactin release, an effect antagonised by phentolamine. Thyrotrophin-releasing hormone (TRH) stimulated the release of prolactin and this stimulation was reversed, in a dose-related manner, by dopamine. TRH also increased the release of growth hormone, in the presence or absence of dopamine. These results demonstrate inhibitory dopaminergic effects on prolactin and growth hormone secretion and stimulatory noradrenergic effects on prolactin release. These aminergic effects may be mediated at pituitary and/or hypothalamic sites.

Animals↗
PubMed1977

Prolactin cells of the human pituitary gland in old age.

Pituitary glands obtained at autopsy from 20 male and 20 female subjects, over 80 years of age, have been investigated with various staining procedures, including the immunoperoxidase technique for the cytological localization of prolactin. Prolactin cells were numerous and well developed in the anterior lobes. The incidence, distribution, granulation and immunoreactivity of prolactin cells showed no apparent difference between old male and female subjects dying of acute or chronic illnesses. It can be concluded that prolactin cells do not regress in old age. The morphologic findings are consistent with the assumption that the pituitary gland is capable of secreting prolactin in aging subjects.

Aged↗
PubMedDate not supplied

LH-RH-dependent synthesis of protein necessary for LH release from rat pituitary glands in vitro.

Anterior pituitary glands of intact diestrous and gonadectomized female rats were incubated with a supramaximally active dose of LH-RH. Puromycin (P) and cycloheximide (C) did not consistently affect the LH release from glands of ovariectomized rats. In intact rats, LH release induced by LH-RH occurred in two phases, an initial one (relatively slow rate of release) and a secondary one (high rate of release). P and C had no effect on the initial phase, but prevented the secondary one. Pre-incubation with LH-RH prevented the effect of P and C added after 4 hours. Since P and C did not affect the total amount of LH present in media and hypophyses, the LH-released during the P- and C-sensitive phase is not newly formed LH. It is concluded that LH-RH induces the synthesis of protein which is necessary for LH-RH-induced LH release. The initial phase of LH release is made possible by protein already present in the glands at the beginning of the experiment.

Animals↗
PubMed1984

Effects of synthetic mammalian thyrotrophin releasing hormone, somatostatin and dopamine on the secretion of prolactin and growth hormone from amphibian and reptilian pituitary glands incubated in vitro.

Pituitary glands of grassfrog (Rana pipiens), bullfrog (Rana catesbeiana), clawed toad (Xenopus laevis) and two species of terrapin (Chrysemys picta and Pseudemys scripta) were incubated in medium containing hypothalamic extract (HE), thyrotrophin releasing hormone (TRH), somatostatin, dopamine, or combinations of these treatments. Prolactin and GH concentrations in the medium were determined by densitometry after polyacrylamide-gel electrophoretic separation. Hypothalamic extract stimulated secretion of both hormones in all species tested. Thyrotrophin releasing hormone stimulated secretion of prolactin and GH, showing a biphasic pattern of response. Dopamine had little effect alone, but inhibited HE- and TRH-stimulated release of prolactin, but not GH, in both amphibia and reptiles. Somatostatin by itself had no apparent effect on release of hormones, but it inhibited HE- and TRH-stimulated release of GH from both amphibian and reptilian pituitary glands. These results indicate that factors affecting mammals and birds also interact in the regulation of secretion of prolactin and GH in lower vertebrate species.

Animals↗
PubMed1999

The effects of age and spontaneous adenoma formation on trophic activity in the rat pituitary gland: a comparison with trophic activity in the human pituitary and in human pituitary adenomas.

The effects of ageing on trophic activity in the pituitary gland and the molecular events that underlie pituitary tumour formation are poorly understood. In the present study we have used an extremely accurate system to analyse trophic activity in human pituitary tumours and compared our findings with trophic activity in spontaneous rat pituitary adenomas and with changes in basal rates of turnover as the animals age. Thin, hematoxylin and eosin-stained pituitary sections from groups of male Wistar rats aged 6 weeks to 16 months, killed at 90-min intervals after receiving a single intraperitoneal bolus of colchicine to block cellular passage through mitosis, were evaluated histologically. Extremely accurate quantification of small changes in the prevalence of trophic events, and thus the rate of cell turnover, was achieved using a dedicated computerized aid to manual cell counting. Results were compared with the prevalence of mitotic activity in 24 spontaneous rat pituitary adenomas and with a series of 97 archival human pituitary adenomas and 24 normal human pituitary glands obtained at autopsy. In rats, average basal pituitary cell turnover declined by over 95% between 6 weeks and 16 months of age. Concurrent with this decline was a marked increase in the prevalence of adenoma formation. The prevalence of mitotic activity in spontaneous rat pituitary adenomas averaged almost twice that seen in normal, young rat pituitary and exceeded 16 times that seen in the pituitary of aged animals. In contrast, when compared to normal human pituitary tissue, average trophic activity in human pituitary adenomas remained extremely low.

Adenoma↗
PubMed1985

[Estrogen-induced pituitary tumors--in relation to the changes in the pituitary gland after estrogen withdrawal].

Pituitary tumors were induced in female rats of Wistar strain by administration of estradiol valerate (E2) and the effect of estrogen withdrawal on E2-induced tumors were studied to elucidate the nature of the induced tumors. Ten mg of E2 was administered to 100 rats intraperitoneally once every 2 weeks, totally four times. Experimental animals were sacrificed at 1 week before, 2, 6, 10, and 14 weeks after stopping injection of E2. The incidence of pituitary tumor and hyperplasia (Table 1). Pituitary glands in each animals were examined and were classified into three groups, namely pituitary tumor, hyperplasia, and normal gland according to histological findings. The incidence of pituitary tumors was highest in rats sacrificed 6 weeks after E2 withdrawal. Pituitary tumors became less frequent and hyperplasias and normal glands became more frequent in rats sacrificed thereafter. Pituitary weight (Table 2, Fig. 1) Irrespective of timing of sacrifice, the weight of pituitary gland (mean +/- SE) was 134 +/- 70 mg in the group which were judged as having a pituitary tumor, 38 +/- 17 mg in the hyperplasia group, and 17 +/- 5 mg in the normal group, respectively. Pituitary weight of control rats were 12 +/- 3 mg. The tumor group had a significantly heavier pituitary weight than hyperplasia and normal groups (p less than 0.01). In each group, there was no significant difference of pituitary weights between animals sacrificed at different intervals after E2 withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed2003

Assessment of the accuracy of computed tomography for measurement of normal equine pituitary glands.

OBJECTIVE: To describe the anatomic features of the pituitary gland region in horses via computed tomography (CT) and determine the accuracy of CT for estimating normal equine pituitary gland dimensions. ANIMALS: 25 adult horses with no clinical signs of pituitary disease. PROCEDURE: Transverse CT images and gross transverse tissue sections were compared in 2 horses. Contrast-enhanced CT of the pituitary gland region was performed postmortem in 23 horses with 4 slice thickness and interval settings (10-mm contiguous or overlapping slices and 4-mm contiguous or overlapping slices). Gross and CT estimates of pituitary gland dimensions were compared via ANOVA. Accuracy of CT estimates was calculated with gross pituitary gland measurements as the known value. RESULTS: Pituitary glands were located between the temporomandibular joints and had contrast enhancement. Mean gross dimensions were length, 2.11 cm; width, 2.16 cm; height, 0.98 cm; and volume, 2.66 cm3. Gross measurements and CT estimates of pituitary gland length from 10-mm contiguous and overlapping slices did not differ. Gross measurements and CT estimates of pituitary gland width from 4-mm contiguous and overlapping slices did not differ. Estimates of height and volume from all CT techniques differed from gross measurements. Accuracies for CT estimates were length, 88 to 99%; width, 81 to 92%; height, 58 to 71%; and volume, 43 to 55%. CONCLUSIONS AND CLINICAL RELEVANCE: Accuracy of estimates of pituitary gland dimension in horses varied with CT scanning technique; via CT estimates of length and width of glands were more accurate than estimates of height or volume.

Animals↗
PubMed2002

Activation of CD8 T cells by antigen expressed in the pituitary gland.

Ag expressed exclusively in the anterior pituitary gland and secreted locally by pituitary somatotrophs can gain access to the MHC class I presentation pathway and activate CD8 T cells. Influenza nucleoprotein (NP) was expressed as a transgene under the control of the human growth hormone (GH) locus control region. Activation of monoclonal F5 CD8 T cells specific for NP resulted in spontaneous autoimmune pathology of the pituitary gland in mice transgenic for both NP and the F5 TCR. Destruction of somatotrophs resulted in drastically reduced GH levels in adult mice and a dwarf phenotype. Adoptive transfer of F5 T cells into NP-transgenic hosts resulted in full T cell activation, first demonstrable in regional lymph nodes, followed by their migration to the pituitary gland. Despite the presence of activated, IFN-gamma-producing CD8 T cells in the pituitary gland and a slight reduction in pituitary GH levels, no effect on growth was observed. Thus, CD8 T cells have access to the neuroendocrine system and get fully activated in the absence of CD4 help, but Ag recognition in this location causes autoimmune pathology only in the presence of excessive CD8 T cell numbers.

Adoptive Transfer↗
PubMed1985

Neoplastic and nonneoplastic lesions in aging female rats with special reference to the functional morphology of the hyperplastic and neoplastic changes in the pituitary gland.

Hyperplastic and neoplastic lesions in the mammary glands, uterus, adrenals and pituitary glands of untreated aging female rats were evaluated. The most common lesions in the uterus, mammary glands and adrenal cortex were endometrial stromal polyps, fibroadenomas and nodular hyperplasias, respectively. A few malignant neoplasias were found in the uterus and mammary glands. The pituitary glands of the senile untreated rats had diffuse hyperplasia and/or hypertrophy of PRL, STH and ACTH cells. In 25 out of 52 rats (48%), pituitary adenomas were detected. Histological examination showed that the adenomas were made up of immature cells, a combination of ACTH and immature cells, prolactin cells, or intermediate zone cells. The cytological changes in the hypophyseal cell types in the senile rats were usually accompanied by spontaneous neoplasias of the mammary glands. The possible role of hypophyseal hormones in the neoplasias of the mammary glands and the adrenal cortex is discussed. The present study has also shown that the variation in the reproductive state of the aging female rats, as assessed from ovarian morphology, had no striking effect on the incidence or the severity of the hyperplastic/neoplastic lesions in the organs examined.

Adenoma↗
PubMed2004

Evaluation of pituitary gland anatomy and histopathologic findings in clinically normal horses and horses and ponies with pituitary pars intermedia adenoma.

OBJECTIVE: To determine size and weight of the pituitary gland and associations between pituitary gland size and weight and sex and age in horses without clinical signs associated with pituitary pars intermedia adenoma (PPIA) and horses and ponies with PPIA. ANIMALS: Pituitary glands from 100 horses without clinical signs of PPIA and 19 horses and 17 ponies with PPIA. PROCEDURES: Pituitary glands were weighed, measured, and examined histologically by use of H&E stain. Masson trichrome and periodic acid-Schiff staining were used, when appropriate. Histologic lesions in the pars intermedia, pars distalis, or both were classified as no significant lesions, single or multiple cysts, focal or multifocal hyperplasia, single or multiple microadenomas, and adenoma. Relative pituitary weight (RPW) was calculated as pituitary weight (grams) divided by body weight (grams). RESULTS: There was an age-related increase in the presence of pituitary lesions in the pars distalis and pars intermedia in geldings, mares overall, and non-pregnant mares. Mean (+/-SD) RPW in horses with PPIA was not significantly different from ponies with PPIA (15+/-5.9 x 10(-6) and 16+/-72 x 10(-6), respectively). Maximum pituitary weight in a horse with PPIA was 13.9 g (RPW, 2.9 X 10(-5)). Plasma glucose concentration was positively correlated with RPW in ponies with PPIA. CONCLUSIONS AND CLINICAL RELEVANCE: Pituitary lesions may be a factor in horses with insulin resistance and laminitis before development of clinical signs of PPIA. Ovarian steroids may be involved in the pathogenesis of lesions in the pars intermedia.

Adenoma↗
PubMed1985

Immunocytochemical demonstration of tissue-type plasminogen activator in endocrine cells of the rat pituitary gland.

We immunocytochemically stained rat pituitary glands using antibodies against plasminogen activators of the tissue type (t-PA) and the urokinase type (u-PA). A large population of endocrine cells in the anterior lobe of the gland displayed intense cytoplasmic immunoreactivity with anti-t-PA. In some areas of the intermediate lobe we found a weak staining, and we observed weakly staining granular structures in the posterior lobe. Controls included absorption of the antibodies with highly purified t-PA. In addition, SDS PAGE followed by immunoblotting of pituitary gland extracts revealed only one band with an electrophoretic mobility similar to that of t-PA when stained with anti-t-PA IgG. No u-PA immunoreactivity was detected in the rat pituitary gland. Sequential staining experiments using antibodies against growth hormone and t-PA demonstrated that the t-PA-immunoreactive cells constitute a large subpopulation of the growth hormone-containing cells. These findings represent the first direct evidence for the presence of t-PA in cell types other than endothelial cells in the intact normal organism. In this article we discuss the implications of the results for a possible role of t-PA in the posttranslational processing of prohormones.

Animals↗
PubMedDate not supplied

Thin section CT of normal pituitary glands.

In order to better understand the CT appearance of the normal pituitary gland, we scrutinized the pituitary glands of 55 patients who had no clinical indication of pituitary abnormality. The superior surface of the pituitary gland was convex in 9 cases (16.4%), flat in 16 (29.1%), and concave in 30 (54.5%). All but one of the glands with upward convexity belonged to patients less than 40 years old. The height of the pituitary glands was from 2 mm to 7 mm in 48 (87.3%) and 7 mm to 9.1 mm in 7 (12.7%); all but one case was less than 40 years old. Although earlier reports have suggested the presence of a pituitary microadenoma when the gland has a convexity of its superior surface or is more than 7 mm in height, these findings can be seen in normal pituitary glands, particularly in younger individuals. Therefore, pituitary microadenoma should be diagnosed carefully in younger patients. The low density area frequently seen in the superior aspect of pituitary glands on axial scans was found to result from the concave superior surface of the gland. The pituitary stalk was off the midline in five patients (9%). Shifting of the pituitary stalk can be seen in the normal pituitary gland and is not always characteristic of microadenoma.

Adolescent↗
PubMed1978

Identification of the LH and TSH-secreting cells in the pituitary gland of the rhesus monkey.

Pituitary glands from juvenile (pre-pubertal) and adult male and female rhesus monkeys were examined following immunocytochemical staining with antisera to the beta subunits of ovine luteinizing hormone (LHbeta) and of human thyroid stimulating hormone (TSHbeta). The LHbeta antiserum reacts with a cell that is PAS-positive, occurs singly and is randomly distributed throughout the pars distalis. The diameter of these cells is approximately 11.5 micrometer. They do not seem to vary in number in either juveniles (pre-pubertals) or adults, or in males or females. There appears to be fewer LH cells in the pituitary glands of pregnant and lactating females. In addition to staining cells in the pars distalis, the antiserum also reacts with a population of cells located in the pars tuberalis. The cells that stain with the anti-TSHbeta serum are confined primarily to the pars distalis. They are approximately 15.8 micrometer in diameter and are generally found in groups or clusters located in the anterior and medical regions of the gland. The TSH cells vary in number from one animal to another; however, this variability is unrelated to the age or the sex of the animals. No demonstrable changes occur in the number of TSH cells during pregnancy or lactation.

Animals↗
PubMed1979

Acute regulation of insulin release by the pituitary gland in relation to hyperinsulinaemia and obesity.

The pituitary glands from mice rendered obese by gold thioglucose treatment and by dietary manipulation, and pituitary glands from lean mice after a high food intake or a glucose load, were shown to stimulate insulin secretion from isolated pancreatic islets. The insulin releasing activity of pituitary glands from obese (ob/ob) mice was reduced by fasting for 24 and 48 h. Results obtained with pituitary glands from ob/ob and from lean ob/+ and +/+ mice suggest that the insulin releasing property manifests a gene dosage effect. Pituitary glands from 3-week-old (young) ob/ob mice stimulated insulin secretion to the same extent as pituitary glands from 3-month-old (adult) ob/ob mice. The pancreatic islets of young ob/ob mice were shown to be somewhat more responsive to stimulation by the pituitary factor than were lean ob/+ or +/+ islets from this age group. The concept that high insulin level, partly under pituitary control, and high caloric intake may be interlinked and may, in combination, be a major factor in producing obesity is discussed. Furthermore, it is suggested that the pituitary insulin releasing factor may play a role in the early development of obesity in the animal models studied.

Aging↗
PubMedDate not supplied

[Colloid cysts of the pituitary gland].

Colloid cysts of the pituitary gland are very rare pathological lesions occurring in sellar region. Their pathogenesis is not clear. They are located between the anterior and posterior lobe of the pituitary. Colloid cysts of the pituitary gland are space occupying lesions and induce hypopituitarism, diabetes insipidus, visual disturbances, etc. They cause pituitary apoplexy too. Magnetic resonance imaging is the preferred neurodiagnostic method in evaluating these lesions. 503 transsphenoidal procedures were performed from January 1996 to February 2001. Hypothalamo-hypophyseal dysfunction was caused by colloid cyst in seven cases. The most frequent presenting symptoms were headaches, oligomenorrhea and loss of libido. Diabetes insipidus was found in two cases before surgery. Colloid cyst induced pituitary apoplexy in one patient. Two patients presented visual disturbances. All our patients were operated on. We performed six transsphenoidal procedures and one transcranial operation. Postoperatively, the endocrine function of the pituitary gland was evaluated. We concluded that transsphenoidal operation is a safe method for treating colloid cyst located in the sellar region.

Adult↗
PubMed2000

MR imaging of the pituitary gland in children and young adults with congenital combined pituitary hormone deficiency associated with PROP1 mutations.

OBJECTIVE: The aim of this study was to clarify the relationship between morphologic changes of the pituitary gland and the genotype of Prophet of Pit-1 (PROP1), a newly discovered gene responsible for congenital combined pituitary hormone deficiency, in a series of eight humans with this disorder. CONCLUSION: Congenital hypoplasia of the anterior pituitary gland is the most common MR imaging finding in patients with combined pituitary hormone deficiency. Our findings suggest a crucial role for PROP1 in pituitary organogenesis as well as anterior pituitary cell differentiation.

Adolescent↗