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This is a report of CT and MRI findings in a patient with a sellar spine which caused deformity of the pituitary gland. The sellar spine is an infrequent anatomical variant characterized by an osseous spine which arises in the midline from the anterior aspect of the dorsum sellae and extends into the pituitary fossa. The CT and MRI findings of sellar spine have been described in previous reports; however, only one investigator reported deformity of the pituitary gland as revealed by CT. This is the first report of the MRI finding of the sellar spine associated with a deformity and superior extension of the pituitary gland, mimicking pituitary hypertrophy.
Twelve pituitary glands from patients suffering from psoriasis obtained at postmortem showed in all cases hyperplasia of human growth hormone-producing cells. These results support the postulated pathomechanism that psoriasis lesions may arise as a result of an increased production of human growth hormone.
The biosynthesis of polyamines, a group of growth-related amines, varied in the rat pituitary gland with the different stages of the estrous cycle. The activity of ornithine decarboxylase (ODC), which catalyzes the rate-limiting step in the biosynthesis of polyamines, was greatly increased in the pituitary gland during the evening of proestrus. Ovariectomy resulted in a disappearance of this cyclic change in polyamine synthesis, whereas estrogen treatment of the ovariectomized rats gave rise to daily afternoon peaks in pituitary ODC activity. Like the prolactin cells, pituitary polyamine biosynthesis appeared to be regulated by dopamine. The induction of ODC activity in the pituitary gland during proestrus or after estrogen treatment was almost completely repressed by bromocriptine, a dopaminergic compound. The dopamine antagonist haloperidol, on the other hand, was a potent inducer of pituitary ODC activity. Neither pituitary DNA synthesis nor prolactin secretion, which both are induced by estrogen, were affected by inhibition of polyamine synthesis, suggesting a biological function of the pituitary polyamines unrelated to these events.
Fifty-three patients undergoing orbital computed tomographic (CT) scanning for symptoms and signs unrelated to the pituitary gland had coronal and sagittal reformations of contiguous 1.5 mm slices through the sella. Mean male gland height was 4.1 +/- 1.1 mm, mean female gland height was 4.4 +/- 1.4 mm; no statistically significant differences with age were identified. Pituitary glands were homogeneous in 58% and inhomogeneous in 42% of patients; 91.5% had flat or concave superior surfaces. Coronal and saggital CT reformations are felt to be important in the evaluation of the pituitary gland.
Anterior pituitary gland of the spontaneous dwarf rat (SDR) with isolated growth hormone (GH) deficiency was studied using immunocytochemistry, cell count and in situ hybridization. The standard immunocytochemistry of five anterior pituitary hormones [adrenocorticotropic hormone (ACTH), luteinizing hormone, thyroid-stimulating hormone, prolactin (PRL) and GH] and S-100 protein failed to detect any cytological difference between normal rats and SDRs, except for the size of different types of cells which were smaller in SDR than in normal rats, and GH cells which were undetectable in the SDR. The cell count study again showed lack of immunoreactive GH cells in the SDR. The population of PRL cells was significantly reduced in the SDR by 40% in male and 30% in female when compared to those of the control. The population of ACTH cells was larger in the male SDR. The population of the immunonegative cells was calculated by subtracting the sum of the percentages of immunopositive cells from 100, and it was found to be remarkably increased in the SDR. The population of immunonegative cells was about 55% in both male and female SDRs, whereas it was calculated to be 18.7% (male) or 10.2% (female) in the control rats. In situ hybridization study using GH cRNA indicated the presence of a considerable number of cells which express GH mRNA in the SDR as well as in the control rats. These results taken as a whole suggest the presence of a number of dysfunctional GH cells in the SDR.(ABSTRACT TRUNCATED AT 250 WORDS)
Ablative therapies for pituitary tumors commonly cause irreversible damage to normal pituitary cells. Toxin gene therapy should therefore ideally be targeted to specific cell types to avoid collateral cell damage. To evaluate cell-type-specific adenoviral gene transfer in the intact pituitary gland we have used stereotaxic transcranial delivery of recombinant adenoviruses in the sheep with continuous assessment of endocrine function. Adenoviral ss-galactosidase expression was driven either by the human cytomegalovirus (hCMV) promoter or the human PRL gene promoter. The hCMV promoter directed adenoviral ss-galactosidase expression in all pituitary cell types, but the PRL promoter restricted this exclusively to lactotropic cells, indicating that this promoter conferred appropriate cell type specificity in the context of adenoviral transduction in vivo. Serial measurements of plasma hormones showed no disruption of endocrine function over 7 days after intrapituitary injection. In summary, this work shows cell type-specific expression of an adenoviral transgene in the mixed cell population of the intact pituitary gland in vivo in a large animal model and indicates that stereotaxic intrapituitary delivery does not disrupt normal endocrine function.
Recent studies have revealed that TRH-like immunoreactivity (TRH-LI) in human serum is predominantly pGlu-Glu-ProNH2 (< EEP-NH2), a peptide previously found in, among others tissues, the pituitary gland of various mammalian species. In the rat pituitary, < EEP-NH2 is present in gonadotrophs and its pituitary content is regulated by gonadal steroids and gonadotrophin-releasing hormone (GnRH). Hence, we reasoned that < EEP-NH2 in human serum may also arise, at least in part, from the pituitary, and that its secretion may correlate with that of gonadotrophins. Therefore, blood was simultaneously sampled from both inferior petrosal sinuses, which are major sites of the venous drainage of the pituitary gland, and a peripheral vein from seven patients with suspected adrenocorticotrophin-secreting pituitary tumours. In addition, in six postmenopausal and six cyclic women, peripheral vein blood was collected at 10-min intervals for 6 h, then a standard 100 micrograms GnRH test was performed. In the sera, TRH-LI was estimated by RIA with antiserum 4319, which binds most tripeptides that share the N- and C-terminal amino acids with TRH (pGlu-His-ProNH2). In addition, LH and FSH were measured in these sera by RIA. In the blood samples taken at 10-min intervals, an episodic variation in serum TRH-LI was noted and pulses of TRH-LI were detected at irregular intervals (from one to six pulses per 6 h) in five postmenopausal and six cyclic women. In general, these pulses did not coincide with those of LH and FSH, suggesting that TRH-LI is not co-secreted with gonadotrophins. Moreover, unlike LH and FSH, serum TRH-LI did not increase during the menopause or after exogenous administration of GnRH. Whereas gonadotrophin concentrations were significantly greater in the inferior petrosal sinus than in peripheral serum, there were no differences in TRH-LI concentrations between these serum samples. In conclusion, serum TRH-LI in humans seems not to be regulated by gonadal steroids or GnRH. Moreover, serum derived directly from the pituitary contained no more TRH-LI than did peripheral serum, which suggests that the human pituitary gland does not secrete significant amounts of < EEP-NH2, and therefore does not contribute significantly to serum TRH-LI concentrations. Further research is required to identify the site of origin of < EEP-NH2 in human serum.
Benzodiazepine binding sites in rat pituitary gland were investigated by equilibrium binding assays in vitro. Using [3H]flunitrazepam [( 3H]FNM), specific binding was demonstrated in both anterior and neurointermediate lobes. Clonazepam and Ro 5-4864 were used to discriminate the binding to central and peripheral-type sites. Both types of binding site were found to be relatively concentrated in the neurointermediate lobe. Scatchard analysis demonstrated that Kd values for [3H]FNM for the two types of sites were similar to those reported in other areas.
We examined the distribution of dopamine and serotonin receptors in human pituitary gland by light microscopic autoradiography using [3H]spiperone as a binding ligand. Clusters of specific binding sites for [3H]spiperone were observed in the anterior pituitary. This clustering is similar to the clustering of lactotrophs observed in immunohistochemical studies. No specific binding sites for [3H]spiperone were present in the posterior lobe of the pituitary gland. We found no evidence for the presence of serotonin-2 receptors (i.e. cinanserin-displaceable [3H]spiperone binding) in human pituitary.
Isolation of prolactin from equine pituitary glands has been described. It has a potency of 42 IU/mg in the pigeon crop-sac test and consists of 199 amino acids. The hormone has only four half-cystine residues in contrast to other mammalian prolactins which have six residues. From NH2-terminal sequence analysis and amino acid composition of cyanogen bromide fragments, the NH2-terminal disulfide loop is missing in the equine prolactin molecule. Circular dichroism spectra indicate that the alpha-helical content of equine prolactin appears to be lower (50%) than that found in the ovine hormone (65%).
The effects of discontinuation and restoration of ovarian influences on the pituitary LH response to LHRH in vitro were investigated. When female rat pituitary glands taken on day 2 of dioestrus were incubated with LHRH the release of LH was low during the first hour (lag phase response) and afterwards a progressive, protein synthesis-dependent increase took place (second phase response), this being the self-priming action of LHRH. Short-term discontinuation (less than 1 day) of ovarian influences on the rat pituitary gland in vivo (ovariectomy) or in vitro (incubation in medium only) resulted in an increased LHRH-induced LH response during the lag phase. The biphasic LH response or the self-priming action of LHRH disappeared completely after long-term discontinuation of ovarian influences on the pituitary gland, LH release being at its maximum from the start of the incubation. The biphasic response was reinstated when ovaries were implanted under the kidney capsules of ovariectomized rats. Auto-implantation of an ovary into the spleen immediately after bilateral ovariectomy did not, however, prevent the disappearance of the LHRH self-priming action. Ovarian activity responsible for the presence of the low LH response during the lag phase was thus effectively removed by the liver, but inhibin-like activity suppressing serum FSH levels remained present. Silicone elastomer implants (s.c.) containing oestradiol-17 beta, implanted for 4 weeks, did not reverse the loss of the biphasic LH response to LHRH. It is concluded that liver-labile factors released by the ovaries keep the pituitary gland in a state of low responsiveness to LHRH.(ABSTRACT TRUNCATED AT 250 WORDS)
The pituitary gland is unique to Chordates, with significant variation within this group, offering an excellent opportunity to increase insight into phylogenetic relationships within this phylum. The structure of the pituitary in adult Teleosts (class: Osteichthyes) is quite different from that in other chordates and is also variable among members of the class. Therefore, a complete description of the structure and development of the pituitary in members of this class is a critical component to our overall understanding of this gland. An obvious teleost model organism is the zebrafish, Danio rerio, as a significant amount of work has been done on the molecular control of pituitary development in this fish. However, very little work has been published on the morphological development of the pituitary in the zebrafish; the present study aims to fill this void. The pituitary develops from cells on the rostrodorsal portion of the head and reaches its final position, ventral to the hypothalamus, as the cephalic flexure occurs and the jaws and mouth form. The pituitary placode is juxtaposed to cells that will form the olfactory vesicles, the stomodeum, and the hatching gland. The volume of the pituitary is greatest at 24 hours post fertilization (hpf). From 24 to 120 hpf, the pituitary decreases in height and width as it undergoes convergent extension, increasing in length with the axis. The adenohypophysis is a morphologically distinct structure by 24 hpf, whereas the neurohypophysis remains indistinct until 72 hpf. The findings of this study correlate well with the available molecular data.
The authors obtained midline sagittal T1-weighted magnetic resonance images of the pituitary gland in 30 female patients: five pregnant; two postpartum; and 23 nonpregnant, of childbearing age, and without evidence of pituitary gland disorder. In pregnant and postpartum patients, the relative signal intensity of the anterior lobe compared with the pons was statistically higher than that in the control group (P < .001). In the pregnant patients, positive correlation was noted between the signal intensity ratio of the anterior lobe and the pons and gestational age. The authors believe that the hyperintensity of the anterior pituitary lobe in pregnant and postpartum patients is a physiologic variation. Because the anterior lobe of an infant may also be hyperintense on T1-weighted images and because the anterior lobes of an infant and a pregnant woman are histologically similar, the mechanism responsible for the hyperintensity in each case may be the same. It is important to know that the anterior lobe may be hyperintense in pregnant or postpartum women, especially in cases of probable pituitary gland abnormality accompanying pregnancy, such as pituitary hemorrhage, Sheehan syndrome, or lymphocytic adenohypophysitis.
The pituitary gland of Latimeria chalumnae is situated rostroventral to the telencephalon. The hollow pituitary stalk is bent forward and is ventrally connected to a saccus-vasculosus-like organ, rostrally to a neurointermediate lobe. The infundibular lumen protrudes far into the neurohypophysial lobules. The elongated principal part (pars cerebralis) of the pars distalis is partly embedded in a dorsal depression of the pars intermedia and caudally invaded by the neurohypophysis. It may be divided into rostral and proximal pars distalis and includes a ramified hypophysial cleft, which continues rostrally as a duct with adjacent islets of pars distalis tissue (parts of a pars buccalis). The adenohypophysis consists of cell cords and follicles. Eight tinctorial cell types can be distinguished: in the rostral islets: large basophils with acidophil globules, in the rostral pars distalis: small basophils, large basophils with amphiphil characters and erythrosin-, orange G-positive acidophils; in the proximal pars distalis: orange G-positive acidophils and small and large basophils, having similar staining properties; in the pars intermedia: one amphiphil cell type.
The distribution of neurotensin-like immunoreactivity (NTLI) in the pituitary gland, hypothalamus, and throughout the gastro-intestinal tract of adult rats was determined by radioimmunoassay (RIA). NTLI concentrations were higher in the hypothalamus than in the pituitary gland or gastro-intestinal tract. The anterior and posterior pituitary gland had almost the same concentration of NTLI. In the gastro-intestinal tract, the mucosal layer of the small intestine had abundant NTLI. The mucosal layer had higher NTLI levels than the muscular layer throughout the alimentary tract.
BACKGROUND: Macrophage migration inhibitory factor (MIF) was one of the first lymphokine activities to be discovered and was described almost 30 years ago to be a soluble factor(s) produced by activated T lymphocytes. In more recent studies, MIF has been "rediscovered" to be an abundant, pre-formed constituent of the anterior pituitary gland and the macrophage, and to be a critical component in the host response to septic shock. Pituitary-derived MIF enters the circulation after infectious or stressful stimuli and appears to act to counterregulate glucocorticoid suppression of cytokine production. MATERIALS AND METHODS: Immunoelectron microscopy utilizing a combination of anti-MIF and anti-pituitary hormone-specific antibodies was used to study the ultrastructural localization of MIF within the anterior pituitary gland. Pituitaries were obtained from resting, unstimulated mice and from mice 16 hr after endotoxin administration. The release of MIF also was investigated in vitro by examining the effect of corticotropin-releasing hormone (CRH_ on the AtT-20, corticotrophic cell line. RESULTS: MIF localizes to granules present exclusively in ACTH and TSH secreting cells. Within each cell type, a subset of granules was found to contain both MIF and ACTH, or MIF and TSH. The pituitary content of MIF-containing granules decreased significantly after experimentally induced endotoxemia. In seven pituitaries examined 16 hr after LPS injection, the number of MIF-positive granules diminished by 38% in corticotrophic cells and by 48% in thyrotrophic cells when compared with controls (p < 0.05). CRH was observed to be a potent MIF secretagogue in vitro, inducing the release of MIF from corticotrophic cells at concentrations lower than that required for ACTH release. CONCLUSION: These data provide ultrastructural information that identify MIF to be a novel anterior pituitary hormone, support earlier studies showing a time-dependent release of pituitary MIF during endotoxemia, and suggest an important, systemic role for MIF in the stress response to infection and other stimuli.
Observations under the operating microscope confirming the presence of a pituitary capsule are reported. This capsule envelops the anterior lobe of the pituitary, the neurohypophysis, and the pituitary stalk. It merges along the stalk with the intracranial pia mater. The origin and nature of this capsule are discussed in light of the known facts of development of the pituitary gland and surrounding structures. It is concluded that the pituitary gland capsule is a derivative of the primitive pia mater.