Single Pituitary Gland Research Articles

Double Metachronous Pituitary Microadenoma: Literature Review and Case Report

Pituitary adenomas, which are benign, slow-growing neoplasms, are commonly associated with hormonal overproduction. They rank as the third most prevalent intracranial tumor, following gliomas and meningiomas. Although double pituitary adenomas are infrequent, they manifest when two adenomas develop within a single pituitary gland. These dual adenomas exhibit typical immunohistochemical and histopathological features. They can be further classified into two distinct types: contiguous and clearly distinct. Neuroradiological imaging facilitates the identification of clearly distinct tumors. We present imaging findings from a rare case of a double pituitary microadenoma. Early diagnosis of this uncommon condition is crucial to prevent potential complications.

Comment on: Double, Synchronous Pituitary Adenomas Causing Acromegaly and Cushing’s Disease. A Case Report and Review of Literature. Endocr Pathol 2013;24:92–99

To the Editor: We read with great interest the recent paper by Zielinski et al. entitled “Double, Synchronous Pituitary Adenomas Causing Acromegaly and Cushing’s Disease. A Case Report and Review of Literature” published in Endocrine Pathology, in which the authors reported a rare case of a 47-year-old man with double clinically active pituitary adenomas causing simultaneous occurrence of signs and symptoms of acromegaly and Cushing’s disease and reviewed the literature regarding multiple pituitary adenomas [1]. In a manuscript with Review of the literature published in Magnetic Resonance Imaging [2], we reported the simultaneous occurrence of multiple non-functioning pituitary microadenomas, the first case with three coexisting tumors diagnosed in vivo up to that time, in a 37-year-old woman who was referred to our outpatient clinic reporting oligomenorrhea, significant weight gain, and persistent frontal and retroocular headache for several years. Physical examination showed moderate hirsutism and “moon face” while both basal and dynamic endocrine evaluation showed the presence of normal hypothalamic pituitary function. Magnetic resonance imaging (MRI) of hypothalamic-pituitary region revealed an enlarged sella turcica occupied by three distinct hypointense areas measuring less than 5 mm in diameter in the left, medial, and right sides of the pituitary, respectively. This finding was confirmed, 6 months later, by a second MRI that also showed a slight increase in dimensions of microadenomas. In the case report by Zielinski et al., basal and dynamic endocrine evaluation confirmed the diagnosis of active acromegaly also revealing a condition of pituitary-dependent hypercortisolism. Preoperative MRI showed a slightly enlarged and asymmetrical pituitary characterized by the presence of two separated intrasellar microadenomas with different intensity. The patient underwent transsphenoidal neurosurgery and the presence of two distinct, separated masses was confirmed. Also in our case, omitted as a reference in the article by Zielinski et al., the preoperative MRI suggestion of three different and well-defined adenomas was confirmed by transsphenoidal surgery. The occurrence of multiple pituitary adenomas is considered as one of the strongest confirmations regarding the role of abnormal extrapituitary regulatory mechanisms in the pathogenesis of pituitary tumors [3]. The coexistence of multiple adenomas in the pituitary gland of the same patient supports the pathogenic role of abnormal stimulatory and/or inhibitory extrahypophiseal factors which are able to promote growth and clonal expansion of genetically altered cells also potentially playing a role in the recurrence of pituitary tumors [4]. In conclusion, the coexistence of two or more adenomas in a single pituitary gland is a rarely reported clinical event and a very infrequent surgical entity, but already in 1999 we described the first case of simultaneous occurrence of triple nonfunctioning pituitary adenomas diagnosed in vivo, whereMRI allowed preoperative identification.

Evaluation of the efficacy of a danazol-loaded intrauterine contraceptive device on adenomyosis in an ICR mouse model

Danazol, a synthetic steroid with antigonadotrophic properties, has been widely used for the treatment of endometriosis and adenomyosis. However, the local application of danazol to the uterus to treat adenomyosis is controversial. The objective of this study is to develop an effective treatment for adenomyosis using danazol via intrauterine contraceptive device (IUCD) delivery. An adenomyosis animal model was established using Institute for Cancer Research, Swiss-derived (ICR) mice, grafted with a single pituitary gland (n = 30). Four months after grafting, IUCDs with three different quantities of danazol were prepared and used to treat the ICR mice with adenomyosis. After 2 months of treatment with a danazol-loaded IUCD, the number of adenomyosis nodules and the hematoxylin-eosin staining scores were measured and compared with mice given daily oral danazol and controls (no adenomyosis). As the danazol dose increased, the nodule number decreased reaching significance at a dose of 2.0 mg per 20 g body weight (P = 0.002). When compared with oral administration, the plasma danazol concentrations with IUCD delivery were low and stable. These results suggest that an IUCD loaded with an appropriate dose of danazol may be an effective treatment for adenomyosis and that human trials are warranted.

Quantification of prolactin messenger ribonucleic acid, pituitary content and plasma levels of prolactin, and detection of immunoreactive isoforms of prolactin in pituitaries from turkey embryos during ontogeny.

The content of prolactin mRNA as well as total prolactin content and type of isoforms of prolactin were measured in single pituitary glands from turkey embryos and poults. Levels of mRNA and pituitary content of prolactin remained low until 5 days before hatching, while plasma concentrations remained low until 2 days before hatching. Levels of prolactin mRNA then increased until the day of hatch, stayed stable during the 3 first days of age, and significantly increased until 2 wk of age. Similar changes were observed in pituitary content and plasma levels of prolactin. Two immunoreactive bands of apparent molecular masses of 24 and 27 kDa, corresponding to the nonglycosylated and glycosylated form of prolactin, respectively, were visualized on Western blots. In pituitary glands from embryos at 22 days of incubation, 31.5% of the protein was glycosylated, whereas in embryos at 27 days of incubation and poults at 1 and 7 days of age, 48.6%, 48.0%, and 56. 0% of prolactin was glycosylated, respectively. The results indicate that the increases in the synthesis and the release of prolactin occur mainly around and after the time of hatching in the turkey embryo. Higher percentages of glycosylated isoforms were associated with increasing levels of total prolactin in the pituitary gland. Thus, the synthesis of prolactin and its post-translational modifications may be important factors involved in the physiologic changes occurring around the time of hatching.

Gonadotropin-I and -II subunit gene expression of male striped bass (Morone saxatilis) after gonadotropin-releasing hormone analogue injection: quantitation using an optimized ribonuclease protection assay.

In fish, both gonadotropin (GtH)-I and -II are involved in the spermatogenic process, but the differential regulation of these hormones by GnRH is still poorly understood. To gain further insight into the GnRH regulation of GtH-I and -II gene expression in the male striped bass, we have developed and optimized a ribonuclease protection assay for the simultaneous measurement of all GtH subunit mRNAs in a single pituitary gland. The RNA extraction protocol enables the determination of GtH protein content in the same sample, thus enhancing the power of the method. Maturing striped bass males were injected intramuscularly with [D-Ala6,Pro9Net]-LHRH (GnRHa) and sampled at 6 and 24 h postinjection. The mRNA levels of the alpha subunit and GtH-IIbeta increased after 6 h (4- and 6-fold, respectively), while the GtH-Ibeta mRNA levels increased only 2-fold after 24 h. Interestingly, GnRHa stimulation caused a significant increase in beta-actin mRNA levels. GnRHa treatment also resulted in a 2-fold decrease in pituitary GtH-II content, associated with a dramatic increase of plasma GtH-II levels from undetectable levels (< 0.2 ng/ml) to 13+/-2 ng/ml after 6 h. These results demonstrate that both GtH-Ibeta and -Ilbeta are expressed during striped bass spermatogenesis and that the two genes are subjected to differential regulation by GnRHa.

Cloning and Characterization of Rainbow Trout (Oncorhynchus mykiss) Somatolactin cDNA and Its Expression in Pituitary and Nonpituitary Tissues

A cDNA clone encoding rainbow trout (Oncorhynchus mykiss) somatolactin (rtSL) has been isolated from a rainbow trout pituitary cDNA library. This 2329-bp cDNA clone includes a very short 7-bp 5′-untranslated region, a coding region of 702 bp, and a long 3′-untranslated region of 1620 bp. The deduced amino acid sequence of rtSL shows a polypeptide of 233 amino acid residues which consists of a 24-amino-acid putative signal peptide followed by a 209-amino-acid mature polypeptide. This mature polypeptide has a molecular weight of 24 kDa. The rtSL shares 99% amino acid identity with chum salmon SL (csSL) and approximately 53–77% amino acid identity with SLs in other fishes, including the 7 conserved cysteine residues. Although a glycosylation site has been identified in SL of other fish species, none is observed in rtSL polypeptide. The level of rtSL mRNA in a single pituitary gland was determined by RNA blot hybridization. Results showed that levels of SL mRNA in pituitary glands of 2-year-old fish were 4- to 7-fold higher than those of 1-year-old fish. The tissue distribution of SL gene expression in adult fish was determined by reverse transcription–polymerase chain reaction (RT-PCR) and DNA blot hybridization. In addition to the pituitary gland, SL mRNA was detected in all tissues examined including brain, gill, heart, kidney, liver, skeleton muscle, spleen, ovary, testis, and immature oocytes. The extrapituitary expression of the SL gene was also detected in embryos and fry. The PCR products which contained the region coding for mature SL from heart and kidney were cloned and characterized. Nucleotide sequence analysis showed that the SL mRNAs in heart and kidney were identical to that in the pituitary gland. These results suggest that, although the pituitary gland is the predominant tissue for producing SL, it is not the only tissue that SL gene is expressed in, and the extrapituitary expression of rtSL gene starts from very early developmental stages.

Decreased angiotensin II binding affinity and binding capacity in the anterior pituitary gland of adult spontaneously hypertensive rats

Angiotensin II (ANG) binding sites were quantified in single pituitary glands from 4-week-old and 14-week-old male spontaneously hypertensive rats (SHR) and age-matched male normotensive Wistar-Kyoto (WKY) control rats after incubation with 125I-[Sar 1]-ANG, autoradiography with computerized densitometry, and comparison to 125I-standards. The maximum binding capacity (B max) decreased while the dissociation constant (K d) for ANG increased in 14-week-old SHR when compared to age-matched WKY control rats (B ram: 265 ± 9 and 224 ± 4 fmol/mg protein; K d: 0.79 ± 0.04 and 1.14 ± 0.08 10 −9 M in WKY and SHR, respectively). Conversely, no difference between rat strains was found in 4-week-old animals. Our results suggest that pituitary ANG binding sites may play a role in the pathophysiology of established genetic hypertension.

Regulation of rat luteinizing hormone subunit messenger ribonucleic acids by gonadal steroid hormones.

Little is known about the hormonal regulation of luteinizing hormone (LH) biosynthesis. We have studied the regulation of LH messenger RNA (mRNA) levels by gonadal-steroid hormones in the rat. In one set of experiments, male and female rats were surgically gonadectomized (GDX) and killed 1, 3, 7, 14, 22, and 31 d postoperatively. In another set of experiments, male and female rats were surgically GDX and were injected subcutaneously with testosterone propionate (500 micrograms/100 g body wt per d) or 17 beta-estradiol 3-benzoate (10 micrograms/100 g body wt per d), respectively, beginning 3 wk postoperatively. Levels of serum LH were determined by radioimmunoassay and levels of LH subunit mRNAs in single pituitary glands were determined by blot hybridization analysis using labeled synthetic oligodeoxyribonucleotide probes that correspond to portions of the coding regions of the rat alpha- and LH beta-subunit mRNAs. 4 wk after gonadectomy, serum LH levels rose nine- and 20-fold, while alpha-subunit mRNA levels rose six- and 10-fold, and LH beta-subunit levels rose seven- and 14-fold, compared with controls in males and females, respectively. In gonadal-steroid hormone-treated male and female GDX rats, serum LH levels fell to 8 and 36% of control values, while alpha-subunit mRNA levels declined to 22 and 19%, and LH beta-subunit mRNA levels declined to 6 and 10% of control values, 48 h after injections were initiated, in males and females, respectively. We conclude that gonadal-steroid hormones negatively regulate the levels of both subunit mRNAs in GDX rats in a pattern that parallels the changes in serum LH values. These data suggest that gonadal-steroid hormone regulation of LH biosynthesis occurs, at least in part, at the level of LH subunit mRNAs due to effects at the transcriptional and/or RNA stability levels.

Rapid Simultaneous Measurement of Ratα- and Thyrotropin (TSH)β-Subunit Messenger Ribonucleic Acids (mRNAs) by Solution Hybridization: Regulation of TSH Subunit mRNAs by Thyroid Hormones*

Using a sensitive method for the simultaneous measurement of TSH subunit mRNAs, we have investigated their hormonal regulation in the pituitary glands of normal and hypothyroid rats. Oligodeoxyribonucleotides (probes) complementary to coding regions of rat alpha- and TSH beta-subunit mRNAs were synthesized. These probes were 5'-end labeled with gamma-[32P] ATP and hybridized with total pituitary RNA obtained from T3-treated and untreated normal and hypothyroid rats. The samples were then exposed to S1 nuclease to digest single stranded nucleic acids. Specific hybridization of probes to the TSH subunit mRNAs would yield double stranded structures resistant to this enzyme. Measurement of the amount of undigested probes by denaturing polyacrylamide gel electrophoresis, autoradiography, and densitometry permits quantification of these mRNAs. Both rat alpha and TSH beta mRNAs were detected with as little as 0.1 microgram total pituitary RNA, representing a more than 10-fold increase in sensitivity compared to a standard RNA blot hybridization assay. Thyroidectomy resulted in a 3- to 5-fold increase, whereas T3 treatment caused a significant decrease in the subunit mRNAs in both normal and hypothyroid animals. However, in all treatment groups, the TSH beta mRNA was affected to a greater extent than the alpha mRNA by the changes in thyroid status. The ratio of alpha- to beta-subunit mRNAs was decreased with hypothyroidism and increased with T3 treatment. This assay allows simultaneous quantification of multiple mRNAs from a single pituitary gland within 48 h and should facilitate studies of the regulation of mRNAs encoding TSH subunits specifically and other pituitary proteins in general.

Superovulation induced by a single pituitary gland transplanted beneath the kidney capsule in adult rats.

Different numbers of rat pituitary glands, taken from male and female rats before and after puberty, were transplanted into various sites in female rats at different stages of the oestrous cycle. Ovulation was checked by counting ova in oviducts on the next expected day of ovulation. Ovulation was induced by transplantation beneath the kidney capsule in early dioestrus of half, one or three glands from 35- to 41-day-old male rats (18.6+/-3.1 (S.E.M.), 32.6+/-2.8 and 49.8+/-4.8 ova shed respectively). The transplantation of glands from mature female rats did not induce supraovulation but inhibited the expected ovulation. The most effective stage for inducing superovulation was early dioestrus and, to a lesser extent, most effective stage for inducing superovulation was early dioestrus and, to a lesser extent, oestrus; transplantation during late dioestrus was ineffective. The effective sites of transplantation were beneath the kidney capsule and intramuscularly but not subcutaneously. Representative pituitary glands from 35- to 41-day-old male rats and adult female rats were assayed for LH and FSH content to interpret the mechanisms of superovulation . The pituitary glands from the male rats contained larger amounts of LH and especially of FSH than those found in the female rats. The experiments indicated that superovulation can be induced successfully by the transplantation of a single pituitary gland from male and immature female rats without any additional treatment with human chorionic gonadotrophin; the failure of the female pituitary transplants to induce superovulation may be due to the insufficient content of LH and FSH.

Variation in the polyadenylylation site of bovine prolactin mRNA.

The poly(A) site of bovine prolactin (bPRL) mRNA was examined by phased priming of cDNA synthesis with oligodeoxynucleotides of the general sequence d(pT8-N-N'). The existence of multiple poly(A)-adjacent sequences in bPRL mRNA was indicated by the production of specific chain-termination fragments with at least three d(pT8-N-N') sequences. Comparison of the sequence bands produced by initiation of cDNA synthesis on the bPRL mRNA template with d(pT8-A-G), d(pT8-G-A), and d(pT8-C-G) revealed a shifted pattern of identical fragments. The shift in position of related sequence bands on the gel suggested that the difference in length of the three major bPRL mRNA species occurred within a span of 12 nucleotides. Sequence analysis conducted with the three d(pT8-N-N') primers gave identical nucleotide sequences for the 3' noncoding region of the bPRL mRNA species and suggested that the mRNA molecules were heterogeneous in length. The existence of multiple poly(A) sites was confirmed by determination of the nucleotide sequence of bPRL cDNA clones containing two of the major poly(A)-adjacent sequences predicted by the oligodeoxynucleotide primers. The mRNA molecules containing these multiple poly(A)-addition sites were shown to be present in the bPRL mRNA obtained from a single pituitary gland. The variation in the poly(A) junction of bPRL mRNA may be a reflection of the processing events at the 3' terminus of mRNAs.

Regulation of pituitary receptors for gonadotropin-releasing hormone during the rat estrous cycle.

A radioiodinated superagonist analog of gonadotropin-releasing hormone (GnRH:[D-Ser(TBu)6]des-GLy10-GnRH N-ethylamide) was used to quantitate the GnRH receptor content of single pituitary glands. This ligand binds with high affinity (Ka = 4.9 X 10(9) M-1) to a single class of sites in pituitary homogenates, without significant tracer degradation, during equilibration for 80 min at 4 C. The GnRH receptor content of adult male rat pituitaries [112 +/- 6.4 (SE) fmol/gland; n = 9] was similar to that of adult female rat pituitaries obtained at estrus or metestrus (104.8 +/- 6.4 fmol/gland, n = 13). Between 1800 h on metestrus and 1800 h on diestrus, the pituitary content of GnRH receptors increased to 200 fmol/gland or greater in each of three separate experiments. The pituitary content of GnRH receptors remained elevated until the time of the serum LH surge, then consistently fell sharply to metesterus levels. These data imply a physiological relevance for the GgRH-binding sites measured by radioassay and demonstrate their relationship to the events of the estrous cycle. The increased GnRH receptor content from the evening of diestrus until late in the afternoon of proestrus may contribute to the enhanced sensitivity of the pituitary to GnRH during proestrus. The close temporal relationship between rising blood estrogen levels and increasing pituitary GnRH receptors suggests that steroid-mediated receptor induction occurs before proestrus. Such an effect of estrogen could be exerted directly upon the pituitary gland or indirectly via the hypothalamus to increase the release of endogenous GnRH, which subsequently induces its own receptors in pituitary gonadotrophs.

The in vitro release of LH during continuous superfusion of single rat anterior pituitary glands.

SummaryStimulation of single rat anterior pituitary glands has been obtained in a continuously superfused system as demonstrated by radioimmunoassay of LH in the superfusate. The results show the possibility of repeatedly stimulating a single pituitary gland, with approximately graded responses to hypothalamic extracts, in presence of a constant basal release rate. The data indicate that a relatively constant basal release rate is obtained under these conditions and that intermittent administration of hypothalamic extracts results in repeated acute release of LH. The period of release was largely limited to the time during which hypothalamic extract was administered. Equivalent amounts of cerebral cortex extract only produced slight increase of LH concentration in the superfusate.

Direct mammotrophic effect of a pituitary homograft in rats.

Grafting a single pituitary gland subcutaneously in the hypophysectomized or hypophysectomized and ovariectomized rat induces profound alveolar lobular growth of the atrophic mammary glands. When an ovary is implanted simultaneously with the pituitary graft, the corpora lutea of the ovarian graft are maintained. The mammotrophic effect of the graft, however, is observed only in the mammary gland on the side where the pituitary graft is implanted; the contralateral gland remains atrophic. It is concluded that the pituitary graft exerts a direct mammotrophic effect on the mammary gland, and that this effect is independent of the presence or absence of ovaries and pituitaries in situ. The extent to which the mammary gland develops appears to depend only upon the amount of prolactin secreted by the pituitary graft, and steroid hormones are probably not needed.

The amount of melanophore-stimulating hormone in single pituitary glands of Xenopus laevis kept under various conditions

The MSH (melanophore-stimulating hormone) content of single anterior and intermediate/posterior pituitary lobes of Xenopus laevis was determined using skin pieces of Anolis carolinensis as test objects. Significant changes in the MSH content of single intermediate/posterior lobes of Xenopus were found after adaptation during a 48 hour period to a black or to a white background. The ratios of the pigment-stimulating potencies of anterior to intermediate/posterior pituitary lobes are about 1:38 for white background-adapted Xenopus, and about 1:9 for black background-adapted animals. The results of the experiments indicate that under the given adaptation conditions the release of MSH is inhibited in white background-adapted Xenopus and the hormone stored in the pituitary. The hormone is continuously released in black background-adapted animals. Exposure to complete darkness does not deprive the pituitary of Xenopus laevis or that of Rana temporaria of its MSH.

Occurrence of three electrophoretic components with melanocyte-stimulating activity in extracts of single pituitary glands from ungulates.

An in vitro method in which the skin of a single test animal (Anolis carolinensis) is used, and which can be used to determine the melanocyte-stimulating activity of a large number of samples, is described. The electrophoretic behavior of the melanocyte-stimulating components present in the pituitary glands of different species of Ungulata was studied. It was found that single beef, pig and sheep pituitaries contain three melanocyte-stimulating components, which behaved in electrophoresis like β-glutamyl-MSH, β-seryl-MSH and a-MSH respectively. These MSH components were present in each single pituitary gland in a ratio which appeared to be more or less constant within a species and which was characteristic for that species.

Reactions of thyroid glands to juxtathyroidal implants of thyrotropic agents.

Detection and measurement of small amounts of thyrotropin, such as might be included in a single pituitary gland, is extremely difficult, if not impossible, by ordinary techniques. The following experiments, in which hypophyseal and control material were implanted in direct contact with the thyroid glands of otherwise intact test animals, were designed for this purpose. In some tests the thyrotropic materials were permitted to remain in contact with the thyroid for as long as nine months to determine the effect of prolonged localized inequality in thyroidarfunction. In other tests the treated animals weresacrificed after 100 hours of contact with the implant to conform to a commonly used interval of observation in bioassay of hypophyseal materials. In the 100-hour tests 23 200-gram guinea pigs of both sexes and 35 threemonth- old male CFWstrain mice were used. Of the guinea pigs, six were aseptically implanted with adult male mouse pituitaries, and six with mouse muscle; five were untreated.