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Malignant tumours of the adrenal gland are uncommon but are associated with substantial mortality. For most tumours resection is the only opportunity for cure. Advances in diagnostic and surgical techniques have improved the detection and treatment of these tumours. Further advances need new ways to make decisions about the use of laparoscopic resection for malignant, or potentially malignant, adrenal tumours. We review studies on the outcome of laparoscopic adrenalectomy for primary adrenal cancer as well as studies on metastatic disease to the adrenal glands. There are few prospective data because of the rarity of this condition. Careful individual judgment by the surgeon remains the cornerstone of safe and complete resection for adrenal malignant disease. [ABSTRACT FROM AUTHOR]

Introduction: Early introduction to essential communication skills is important. We sought to determine if a handoff curriculum (HC) would improve confidence, decrease anxiety, and increase participation in clinical handoffs during the surgical clerkship., Methods: A multi-center prospective cohort study was performed at two medical schools. Training in the intervention group (HC) consisted of a didactic lecture, video review, and practice session. Students completed a pre-clerkship knowledge test and confidence/anxiety/handoff experience questionnaire pre- and post-clerkship., Results: There were no significant differences in pre-clerkship handoff experiences between institutions except having previously witnessed a verbal handoff (School A 96.4% versus School B 76.2%, P = 0.01). While there were no significant differences in post-clerkship confidence or anxiety, HC students were significantly more involved with written sign-outs (52.9% versus 18.2%, P = 0.02) and verbal handoffs (29.4% versus 4.6%, P = 0.03)., Conclusions: Medical students exposed to handoff training shared similar confidence and anxiety scores compared to those that were not, however, they were more involved in handoff experiences during their surgical clerkship. Early introduction to handoff skills may encourage greater participation during subsequent clinical experiences., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: Adrenalectomy is performed to treat functional pathology and remove tumors of malignant concern. The National Surgical Quality Improvement Program (NSQIP) risk calculator predicts 30-day complications and length of stay following index surgical procedures. We assess whether this tool accurately predicts complications following adrenalectomy procedures at a tertiary care academic medical center., Methods: A retrospective review was performed for all adrenalectomies at a single institution from 2004 to 2016. 197 patients underwent adrenalectomy without concurrent resections. Predicted risk for NSQIP complications was calculated for each patient. The mean predicted and observed risks (%) at 30 days across all patients within each category were determined, and these were compared with two-sided one-sample t tests., Results: Of 197 adrenalectomies, 180 were laparoscopic and 17 were open. For laparoscopic adrenalectomy, ten (5.5%) complications were observed including nine (5%) graded Clavien III or greater. All observed complication rates were significantly different than predicted (p values for all < 0.005). Mean observed length of stay was also significantly less than predicted (1.6 versus 2.1 days, p < 0.001). In the open adrenalectomy subgroup, there were no observed complications with observed mean length of stay equivalent to predicted (5.8 versus 5.3, p = 0.08) without a higher readmission rate (5.9 versus 6.0%)., Conclusions: Statistical differences were noted between the actual complication rates of adrenalectomy versus those predicted by the NSQIP calculator. Certain observed differences may not necessarily have clinical significance. Urology procedure-specific calculators may better refine predictions for sub-specialty procedures with future work requisite to determine performance across all practice settings.

Tattoos present a diagnostic challenge for dermatologists. Various reactions to tattoo have been identified in the literature ranging from allergic, to infectious, to neoplastic. Of the neoplastic cases identified, it is unclear whether the tattoo ink was directly causative, or if the cases were merely coincidence, as the number of cutaneous malignancies has also been on the rise. We present a novel case of two desmoplastic intradermal Spitz nevi arising within red tattoo ink.

Objective: Inherited endocrinopathies are rare tumor predisposition syndromes associated with significant morbidity and mortality and have implications for both patients and their families. Prior studies suggest that early diagnosis of inherited endocrinopathies may reduce morbidity and mortality. Although genetic counseling and testing can help inform the appropriate management of at-risk relatives, barriers to care still exist. We explored patient perceptions to identify barriers and promote the uptake of genetic counseling., Methods: An anonymous survey of patients from a multidisciplinary inherited endocrinopathy clinic at a tertiary care, university-based medical center was conducted. Data collected and analyzed included demographics, socioeconomic status, perceived risks, benefits, and both motivating and dissuading factors to genetic counseling and testing., Results: Our study suggests barriers to genetic testing include concerns regarding cost and the potential for discrimination with respect to employers and insurers., Conclusion: This highlights the importance of genetic counseling to discuss benefits of genetic testing, while dispelling misperceptions. Knowledge of the common barriers to genetic counseling and testing can guide initiatives and education to foster genetic testing of at-risk relatives in the inherited endocrinopathy population., Abbreviations: FMTC = familial medullary thyroid carcinoma GINA = Genetic Information Nondiscrimination Act MEN1 = multiple endocrine neoplasia 1 MEN2A = multiple endocrine neoplasia 2A MEN2B = multiple endocrine neoplasia 2B MTC = medullary thyroid cancer PGL-PCC = paraganglioma-pheochromocytoma.

We conducted a retrospective study to compare operating times and costs in patients who underwent guided parathyroidectomies with either (1) technetium-99m ((99m)Tc) multiplex ion-beam imaging (MIBI) parathyroid scintigraphy with single-photon emission computed tomography/computed tomography (SPECT/CT) fusion images or (2) sestamibi dual-phase (99m)Tc MIBI planar parathyroid scintigraphy alone preoperatively. Our study population was made up of the first 24 patients at our facility who had undergone SPECT/CT parathyroid imaging with technetium-99m ((99m)Tc) MIBI and a group of 24 patients who had undergone MIBI planar imaging alone. Patient demographics, preoperative laboratory test results, operating times, and hospital charges were analyzed. We found that less operating time was required for the planar MIBI group than in the SPECT/CT group (mean: 135 vs. 158 min), although the difference was not statistically significant. Likewise, the total cost of treatment was lower in the planar MIBI group (mean: $10,035 vs. $11,592); the difference was statistically significant by one measure (p × 0.02, Wilcoxon rank sum test) but not by another (p × 0.06, Student t test). Although SPECT/CT is efficient for patients with small and difficult-to-localize adenomas, it has yet to demonstrate greater efficacy or cost-effectiveness than planar MIBI for routine parathyroidectomy in patients with primary hyperparathyroidism when an easily identifiable parathyroid adenoma is localized.

Purpose: Patients with primary hyperparathyroidism routinely undergo preoperative imaging to localize the abnormal gland to facilitate a guided parathyroidectomy. These techniques include neck ultrasound (US), dual phase planar technetium-99m ((99m)TC) sestamibi (MIBI) scans, single photon emission computed tomography (SPECT), combined SPECT/CT, and four dimensional CT scans (4D CT). Despite appropriate preoperative imaging, non-localization of abnormal glands does occur. This study aims to determine whether non-localization is the result of radiologic interpretive error or a representation of a subset of truly non-localizing parathyroid adenomas., Materials and Methods: A retrospective study was performed; two senior radiologists reinterpreted the preoperative imaging (US and MIBI scans) of 30 patients with initially non-localizing studies. All patients underwent parathyroidectomy for primary hyperparathyroidism at a tertiary referral center. Both radiologists were blinded to the scores of his colleague. The results were compared for inter-reader reliability using Cohen's kappa test., Results: Twenty-nine of thirty nuclear studies were found to be negative on reinterpretation. The readers agreed in 86.67% of their observations, with a kappa (κ) value of 0.706 (SE=±0.131, 95% confidence interval for κ =0.449-0.962). One of eighteen ultrasounds had positive localizations on reexamination, however, the inter-observer agreement was only 55.6%, with a kappa value of 0.351 (SE=±0.139, and 95% confidence interval for κ =0.080-0.623). Overall, no statistically significant difference in preoperative and retrospective interpretation was found., Conclusion: This study identifies a subset of parathyroid adenomas that do not localize on preoperative imaging despite sound radiographic evaluation., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The relationship between polycythemia vera (PV) and primary hyperparathyroidism is not well understood. Remission or improvement of PV following parathyroidectomy in the setting of primary hyperparathyroidism has previously been described; however, long-term outcomes are not well characterized. We describe a patient with JAK2 mutation negative PV and primary hyperparathyroidism, with a dramatic, but ultimately transient, improvement in hemoglobin following resection of a parathyroid adenoma. While screening for hyperparathyroidism may be useful in the setting of PV, indications for parathyroidectomy should be driven by symptomatology or established criteria, not the desire to affect the clinical course of PV.

Background: The American Association of Endocrine Surgeons initiated a fellowship match in 2007. The profile of applicants who successfully match into an endocrine surgery (ES) fellowship has not previously been characterized., Methods: An institutional review board-approved, web-based survey was distributed to recent and current ES fellows., Results: The survey response rate was 62% (56/90). The overall mean age was 33 years (standard deviation ±3), 54% were female, and 37% self-identified as non-white. Only 5% entered their surgical training with the aim of specializing in ES. During residency, respondents were exposed to high volumes of index ES cases. Sixty-two percent had dedicated research time. At the time of fellowship application, the median number of publications was 5 (range, 0 to 25), and 30% of respondents had additional advanced degrees., Conclusion: Entering ES fellows has diverse backgrounds, with strong academic credentials. These data help inform the career mentoring of aspiring ES applicants., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant disorder that presents with renal tumors, pulmonary cysts with spontaneous pneumothoraces, and skin hamartomas. We present a case of a 67-year-old female with multiple endocrinopathies and a history of BHD syndrome. In 2011, a thyroidectomy with a four-gland parathyroidectomy was performed for toxic multinodular goiter (TMNG) and parathyroid hyperplasia. On frozen section, a tumor was identified next to a hypercellular parathyroid. After being worked up, this tumor was determined to be an adult rhabdomyoma. This represents the first time that both TMNG and parathyroid hyperplasia have been present in a BHD patient. Additionally, this is the first adult rhabdomyoma reported in a patient with BHD syndrome. Adult rhabdomyomas have no reported associations; however, potential colocation of the mutation in BHD syndrome and translocation in adult rhabdomyomas on chromosome 17p suggests a possible connection. Further work is needed to better understand this connection.

Background: Little is known about costs associated with differentiated thyroid cancer (DTC) and follow-up care. This study used data from the Surveillance Epidemiology and End Results (SEER) database to examine cumulative costs attributable to disease stage and treatment options of DTC in elderly patients over 5 years., Methods: We identified 2,823 patients aged >65 years with DTC and 5,646 noncancer comparison cases from SEER Medicare data between 1995 and 2005. Cumulative costs were obtained by estimating average costs/patient in each month up to 60 months after diagnosis. We performed multivariate analyses of costs by fitting each monthly cost to linear models, controlling for demographics and comorbidities. Marginal effects of covariates were obtained by summing coefficients over 60 months., Results: Cumulative costs were $17,669/patient the first year and $48,989/patient 5 years after diagnosis. Regional disease was associated with higher costs at 1 year ($9,578) and 5 years ($8,902). Distant disease was associated with 1-year costs of $28,447 and 5-year costs of $20,103. Patients undergoing surgery and radiation had a decrease in cost of $722 at 5 years., Conclusion: DTC in the elderly is associated with significant economic burden largely attributable to patient demographics, stage of disease, and treatment modalities., (Copyright © 2013 Mosby, Inc. All rights reserved.)

Objective: Data from the Surveillance Epidemiology and End Results Medicare-linked database were used to estimate the incidence of and risk factors associated with recurrent thyroid cancer, and to assess the impact of recurrence on mortality following diagnosis, controlling for mortality as a competing risk., Design: We identified 2883 patients over 65 years of age diagnosed with a single, primary well-differentiated thyroid cancer between 1995 and 2007. A recurrence was considered if the patient had evidence of I-131 therapy, imaging for metastatic thyroid carcinoma, or complete thyroidectomy beyond 6 months of diagnosis. Competing risk regressions were performed using Cox proportional hazards models with 1- and 2-year landmarks., Results: Recurrence was observed in 1117 (39%) of the 2883 patients in the cohort. Age, stage, and treatment status were significant risk factors for developing recurrent disease (P<0.0001). Patients with recurrent disease had a higher risk of all-cause mortality within 10 years of diagnosis than patients with no recurrence at 1- and 2-year landmarks. Patients with follicular histology and a recurrence were less likely to die from cancer (hazard ratio 0.54; P=0.03) than patients with no recurrence., Conclusions: The rate of recurrence of well-differentiated thyroid carcinomas in this sample of elderly patients was 39%. Extent of disease and older age negatively impacted the risk of recurrence from differentiated thyroid cancer. In these data, patients with follicular histology and a recurrence were less likely to die, suggesting that mortality and recurrence are competing risks. These data should be taken into account with individualized treatment strategies for elderly patients with recurrent malignant thyroid disease.

Objective: To discuss the implications of a young age at diagnosis in a family member with hyperparathyroidism-jaw tumor syndrome, the youngest published case to date, due to a mutation of the CDC73 gene (formerly known as HRPT2); to review this family with regard to modifications of guidelines for surveillance of hyperparathyroidism and other associated features in affected and at-risk relatives; and to discuss surgical recommendations in this syndrome., Methods: A review of English-language publications in PubMed and a review of GeneReviews were conducted pertaining to the subject of familial hyperparathyroidism. A case is described, and the family pedigree is discussed., Results: Review of the literature revealed that CDC73-related disorder has not previously been reported in patients younger than 10 years. This finding has been the basis for the recommendation for initiation of surveillance for disease manifestations at that age. Review of the family history of our current patient revealed a 7-year-old nephew with hypercalcemia attributable to primary hyperparathyroidism., Conclusion: Surveillance of hyperparathyroidism in affected persons and genetic testing of relatives at risk are currently recommended to start at 10 years of age. We recommend that these be conducted at a younger age, preferably 5 to 10 years before the earliest diagnosis of hyperparathyroidism within the family, and potentially at birth in families with a known mutation of the CDC73 gene, in light of the malignant potential of the disease.

Background: Prolonged therapeutic exposure to lithium compounds can have adverse consequences on calcium homeostasis. A unique form of hyperparathyroidism appears to be causally linked to chronic lithium exposure. We provide a comprehensive review of relevant literature using a structured, evidence-based approach., Methods: Published data were identified from systematic electronic literature searches. References are assigned a level of evidence according to a validated classification schema., Results: Level III and V evidence supports an etiologic link between sustained lithium therapy and both hypercalcemia and hyperparathormonemia (grade C recommendation). Level V evidence supports the use of preoperative parathyroid imaging if a focused exploration is planned (grade C recommendation). Level V evidence supports the use of intraoperative parathyroid hormone monitoring to guide appropriate surgical therapy (grade C recommendation). There is conflicting and equally weighted level V evidence supporting a routine preoperative plan of bilateral neck exploration versus selective unilateral exploration (no recommendation). There may be a role for calcimimetic drug therapy as an alternate, nonsurgical means of controlling lithium-associated hyperparathyroidism (grade C recommendation)., Conclusions: Evidence-based recommendations support screening of patients on chronic lithium therapy for hypercalcemia. Appropriate surgical therapy may consist of either a bilateral or a unilateral approach when performed by an experienced endocrine surgeon. Focused approaches should be guided by preoperative imaging and intraoperative hormone monitoring. Calcimimetic therapy is a potential alternative to parathyroidectomy.

Background: Patients with hereditary pheochromocytoma are at risk of the development of bilateral disease. Partial adrenalectomy can preserve adrenal function to avoid the morbidity associated with medical adrenal replacement. Here, we report a multimedia case study of synchronous bilateral partial adrenalectomy by the laparoscopic approach., Methods: A 13-year-old patient with von Hippel-Lindau disease was found to have high urinary metanephrines and normetanephrines. Computed tomography showed bilateral adrenal tumors (2.5 cm on the right side and 0.9 cm on the left). MIBG scan showed positive uptake in the right adrenal gland without extra-adrenal uptake. After adequate adrenergic blockade, the patient underwent laparoscopic partial adrenalectomy bilaterally., Results: The left side was approached first with the patient in the right decubitus position. Intraoperative ultrasound was performed to determine the line of tumor excision, which was carefully planned to preserve most of the normal-appearing gland. Both tumors were excised completely with good hemostasis. The main adrenal veins of both sides were precisely preserved. Operative time was 228 minutes. No clinically important hemodynamic fluctuations were noted. Pathologic examination confirmed bilateral entirely excised pheochromocytomas. The patient has not required exogenous corticosteroid replacement at follow-up., Conclusion: Laparoscopic partial adrenalectomy for bilateral pheochromocytomas is safe and technically feasible. It should be considered the treatment of choice for hereditary pheochromocytoma.

Background: Chronic lithium therapy may cause hyperparathyroidism (HPT). The utility of intraoperative parathyroid hormone monitoring (IOPTH) in these patients is unknown. The authors' hypothesis was that multiglandular disease is more common in these patients, and the ability of IOPTH to predict cure may be limited., Methods: Twelve patients had HPT during chronic lithium therapy and underwent parathyroidectomy with IOPTH. Criteria for curative resection were a decrease > or =50% from baseline and into the normal range. Calcium and PTH levels were measured during follow-up., Results: Preoperatively, mean calcium was 11.0 +/- 0.1 mg/dL, and PTH was 116 +/- 14 pg/mL. Fifty percent of patients had multiglandular disease confirmed by IOPTH levels. Mean IOPTH decrease from baseline was 74 +/- 4%. Although 10 of 12 patients met criteria for curative resection, only 8 remain normocalcemic. The 2 patients who did not meet criteria remain normocalcemic. Mean postoperative calcium for all patients was 9.5 +/- 0.2 mg/dL. Of the 10 normocalcemic patients, 4 also have hyperparathormonemia (mean PTH, 119 +/- 19 pg/mL)., Conclusions: The incidence of multiglandular disease in HPT after chronic lithium exposure is higher than standard HPT. The ability of IOPTH to predict durable normocalcemia is limited. Bilateral neck exploration should be considered for these patients regardless of whether IOPTH monitoring is used.

Background: Intraoperative parathyroid hormone (IOPTH) monitoring is common during parathyroidectomy. We hypothesized that sample site (peripheral vs central vein) may impact IOPTH interpretation., Methods: Two hundred and one patients underwent curative parathyroidectomy for single-gland disease. IOPTH was drawn peripherally (PV) in 114 patients and centrally (CV, jugular vein) in 87 patients. Decrease from baseline IOPTH and the presence of a normal value at 10 and 15 minutes were determined. The slope of IOPTH decay was calculated. These data were compared between sample sites., Results: Median baseline IOPTH was 268 pg/mL (CV) and 191 pg/mL (PV, P = .003). The mean IOPTH decay slopes were -0.75 (PV) and -0.76 (CV, P = NS), and the mean percent IOPTH decrease at 10 minutes was 79% PV and 80% CV (P = NS). At 10 minutes, a > or =50% drop from baseline was seen in 94% (CV) versus 97% (PV) of patients ( P = NS), resulting in a median IOPTH of 40 pg/mL (CV) versus 34 pg/mL (PV, P = .09). By 15 minutes, the central IOPTH had decreased by > or =50% of baseline in 98% of patients ( P = NS when compared to the 10-minute PV site)., Conclusions: IOPTH kinetics are largely the same for PV and CV sample sites, but baseline values are higher with central sampling. Consequently, CV IOPTH levels are generally higher at 10 minutes, but this discrepancy resolves by 15 minutes. The surgeon utilizing CV samples may need to extend the sampling period.

Minimally invasive approaches have dramatically reduced morbidity associated with adrenalectomy. There has been concern that an increased frequency of adrenal imaging along with the advantages of less morbidity could influence the indications for adrenalectomy. We tested the hypothesis that adrenalectomy has become more common over time and that benign diseases have been increasingly represented among procedural indications. The Nationwide Inpatient Sample (NIS) database was utilized to determine the incidence of adrenalectomy and the associated surgical indications in the United States between 1988 and 2000. All discharged patients were identified whose primary ICD-9-CM procedure code was for adrenalectomy, regardless of the specific surgical approach (laparoscopic adrenalectomy was not reliably coded). This subset was then queried for associated ICD-9-CM diagnostic codes. Linear regression and t-tests were utilized to determine the significance of trends. The total number of adrenalectomies increased significantly, from 12.9 per 100,000 discharges in 1988 to 18.5 per 100,000 discharges in 2000 (p = 0.000003). The total number of adrenalectomies with a primary ICD-9-CM code for malignant adrenal neoplasm did not increase significantly: from 1.2 per 100,000 discharges in 1988 to 1.6 per 100,000 discharges in 2000 (p = 0.47). The total number of adrenalectomies with a primary ICD-9-CM diagnostic code for benign adrenal neoplasm increased significantly, from 2.8 per 100,000 discharges in 1988 to 4.8 per 100,000 discharges in 2000 (p = 0.00002). The average percentage of adrenalectomies performed for malignant neoplasm was significantly higher during the period 1988--1993 when compared to 1994--2000 (11% vs. 9%; p = 0.002). The average percentage of adrenalectomies performed for benign neoplasm was significantly lower during 1988--1993 when compared to 1994--2000 (25% vs. 28%; p = 0.015). Adrenalectomy is being performed with increasing frequency. This is associated with an increase in the proportion of adrenalectomies performed for benign neoplasms. Assuming no significant change in disease prevalence during the study period, these data suggest that indications for adrenalectomy may have changed somewhat over that period.

Background: Endocrine surgery is a discipline that is dedicated to high-quality care of patients with endocrine surgical disease. The relationship between its "identity" as a separate field and clinical practice patterns is not known., Methods: The National Inpatient Sample was searched by the International Classification of Diseases-9th revision-Clinical Modification codes for parathyroidectomy, thyroidectomy, and adrenalectomy for the years 1988 through 2000. The surgeons who performed these operations were profiled by 2 methods: Method A, by the percentage of the total primary International Classification of Diseases-9th revision-Clinical Modification procedure codes that were the selected endocrine procedures; method B, by absolute number of index endocrine procedures performed per year. Only patients with complete coding data for the surgeons were included., Results: In this sample, surgeons whose practice was comprised of 25% or less of these endocrine procedures performed 11,071 parathyroidectomies (78% of total), 46,210 thyroidectomies (82% of total), and 4209 adrenalectomies (94% of total). In contrast, surgeons whose practice was comprised of more than 75% of these endocrine procedures performed 769 parathyroidectomies (5% of total), 1560 thyroidectomies (3% of total), and 128 adrenalectomies (3% of total)., Conclusion: If these data can be extrapolated to indicate generalized practice patterns, the majority of common operations for endocrine disease are performed by surgeons whose practice is not focused on endocrine surgery. However, much of this effect is due to the fact that non-endocrine surgeons far outnumber endocrine surgeons. This understanding of clinical practice patterns will be important to consider during future studies that seek to determine the relationship between surgeon volume and patient outcomes.

The hypothalamic hormone gonadotropin-releasing hormone (GnRH) plays a critical role in reproductive function by regulating the biosynthesis and secretion of the pituitary gonadotropins. Although it is known that GnRH induces luteinizing hormone beta (LHbeta) gene transcription, the mechanisms by which this occurs remain to be elucidated. We have shown previously that GH3 cells transfected with the rat GnRH receptor cDNA (GGH3-1' cells) support the expression of a cotransfected fusion gene composed of 797 base pairs of rat LHbeta gene 5'-flanking sequence and the first 5 base pairs of the 5'-untranslated region fused to a luciferase reporter (-797/+5LHbetaLUC) and respond to a GnRH agonist with a 10-fold stimulation of activity. Furthermore, we have shown that DNA sequences at -490/-352 confer GnRH responsiveness to the rat LHbeta gene. We have now identified two putative binding sites for Sp1, a three-zinc-finger transcription factor, within this region. Using electrophoretic mobility shift assay, DNase I footprinting, and methylation interference assays, we demonstrate that Sp1 can bind to these sites and that Sp1 is responsible for DNA-protein complexes formed using GGH3-1' and alphaT3-1 nuclear extracts. Mutations of the Sp1 binding sites, which block binding of Sp1, blunt the stimulation of the LHbeta gene promoter by GnRH. These data define GnRH-responsive elements in the LHbeta 5'-flanking sequence and suggest that Sp1 plays an important role in conferring GnRH responsiveness to the LHbeta subunit gene.

GnRH plays a critical role in reproductive development and function by regulating the biosynthesis and secretion of the pituitary gonadotropins, LH and FSH. Although it is known that GnRH induces gonadotropin subunit gene transcription, the mechanism by which this occurs has not been elucidated. Studies have been hindered by the lack of available cell lines that express the LH and FSH subunit genes and respond to GnRH. We have transfected the rat pituitary GH3 cell line with the rat GnRH receptor complementary DNA. These cells, when cotransfected with regulatory regions of the LH or FSH subunit genes fused to a luciferase reporter gene, respond to GnRH with an increase in promoter activity comparable to that seen in primary rat pituitary cells. In this study, we have used this cell model to identify cis-acting elements of the LHbeta gene that mediate stimulation by GnRH. Analysis of a series of 5'-deletion and internal deletion constructs has revealed two regions of the rat LHbeta gene promoter involved in mediating the response to GnRH, region A (-490/-352) and region B (-207/-82). Fusion of region A upstream of a heterologous minimal promoter linked to the luciferase gene conferred GnRH responsiveness to the promoter, whereas region B did not. However, the presence of both regions A and B conferred a greater GnRH response than region A alone. Electrophoretic mobility shift assay revealed the presence of a protein(s) binding to region A using GH3 as well as alphaT3-1 nuclear extracts. Thus, region A (-490/-352) confers GnRH responsiveness to the LHbeta subunit gene and binds to a protein(s) present in pituitary cell lines. DNA sequences in region B (-207/-82) also contribute to GnRH responsiveness. The identification of putative GnRH response elements in the rat LHbeta gene promoter will aid in elucidation of the mechanisms of regulation of gene expression by GnRH.

The regulation of LH and FSH subunit gene expression is under the control of GnRH. Physiological changes in the frequency of pulsatile GnRH release from the hypothalamus result in differential stimulation of alpha-, LHbeta-, and FSHbeta-gene expression. Previous studies indicate that the GnRH receptor couples to G proteins of the G(q/11) family, with phosphoinositide turnover and its resultant increase in intracellular calcium concentration and protein kinase C (PKC) activation, to stimulate secretion of LH and FSH. However, the molecular mechanisms by which GnRH mediates its transcriptional effects remain largely unknown. We used GH3 cells, constitutively expressing the rat GnRH receptor (GGH(3)-1' cells) and transiently transfected with a luciferase reporter gene controlled by either the alpha, LHbeta, or FSHbeta gene regulatory region (alphaLUC, LHbetaLUC, and FSHbetaLUC, respectively), to examine the roles of several signal transduction pathways in the GnRH-mediated stimulation of gonadotropin subunit gene expression. Activation of PKC by phorbol, 12-myristate, 13-acetate resulted in an increase in the luciferase activity of all three gonadotropin subunit gene reporter constructs. Phorbol, 12-myristate, 13-acetate had a greater stimulatory effect, relative to the maximal stimulation with GnRH, for the beta-subunit genes than for the alpha-subunit gene. Depletion of PKC, or inhibition of PKC by GF109203X, demonstrated that PKC-dependent pathways play a larger role in the GnRH-mediated transcriptional control of the LHbeta- and FSHbeta-genes than the alpha-subunit gene. In contrast, an L-type calcium channel agonist, Bay K 8644, was able to stimulate alphaLUC but not LHbetaLUC or FSHbetaLUC. Nimodipine, an L-type calcium channel antagonist, had a larger inhibitory effect on the GnRH response of alphaLUC, relative to LHbetaLUC or FSHbetaLUC. We conclude from these results that the differential regulation of gonadotropin subunit gene expression by GnRH is caused, in part, by differential use of signal transduction pathways, activated upon GnRH binding.

Angiotensin II (AII) receptor binding assays were performed in rat adipocytes from three separate anatomic depots. Fat cells were isolated by collagenase digestion, and plasma membranes were prepared from the epididymal, mesenteric, and retroperitoneal fat depots of male Sprague-Dawley rats at 100 days of age. Binding of 125I-labeled [Sar1,Ile8]AII was rapid, saturable, and specific in membranes from all depots, identifying a receptor with a similar affinity of approximately 1 nM. Site-associated differences in receptor number were observed, with epididymal and mesenteric fat cell membranes exhibiting significantly more receptors than retroperitoneal fat cells when binding was expressed per unit of membrane protein. When corrected for cell volume, the number of receptors per cell ranked epididymal > retroperitoneal > mesenteric. Inhibitory constants for the peptide agonists AII and AIII and the peptide antagonist [Sar1,Ala8]AII indicated similar affinities in all three depots. Because the receptor has been classified pharmacologically into two subtypes, the AT1 selective antagonist losartan, and the AT2 selective antagonist PD 123,319 were used to classify the adipocyte receptor, indicating an AT1 subtype with an affinity for losartan in the mesenteric and retroperitoneal adipocytes that was significantly greater than the epididymal. Similar studies were performed in adipocyte membranes obtained from human omental and subcutaneous adipose tissue, revealing the presence of an AII receptor in both depots with an affinity of approximately 10 nM for losartan. These data indicate site-specific differences in AII receptor number in fat cell membranes from rats and the existence of human adipocyte AII receptors, suggesting that the adipocyte is significant for the peripheral metabolism of components of the renin-angiotensin system.

To better understand the role of the mitogenic vasoactive peptide angiotensin II (AII) in growth and differentiation, we have investigated the existence of membrane receptors for this peptide in rat adipocytes. Following isolation of epididymal fat cells, membrane protein was removed and incubated with varying concentrations of 125I-AII with or without submicromolar concentrations of unlabeled AII. Binding of AII was highly specific, rapid, and reversible. Scatchard analysis indicated that adipocyte membranes contain a high-affinity AII receptor with a Kd of 0.90 nmol/L and a binding site concentration (Bmax) of 53.7 fmol/mg protein. Additional pharmacologic analyses resulted in a rank order potency for peptide agonists and antagonists similar to that reported for the vascular receptor. Determination of subtype specificity with selective organic compounds indicated that the epididymal adipocyte receptor was displaced at low concentrations of DuP753, a selective AT1 subtype antagonist. These studies have successfully identified and characterized a high-affinity membrane receptor for AII in fat cells, further establishing adipose tissue as a peripheral site containing regulatory components of the local renin-angiotensin system.

To detect the presence in adipose tissue of peptides known to affect tissue growth and to investigate potential regional differences, epididymal and perirenal adipose tissue depots from male Sprague-Dawley rats were separated into adipocyte and stroma-vascular fractions by collagenase digestion, sequential centrifugation and filtration. Identity and integrity of the fractions were demonstrated by light and electron microscopy, while dose-response curves for angiotensin-converting enzyme (ACE) were performed, revealing maintained functional capacity of the stroma-vascular fraction. ACE, atrial natriuretic peptide (ANP), and transforming growth factor-alpha (TGF-alpha) concentrations were significantly greater in epididymal than perirenal stroma-vascular tissue. Adipocyte fractions from both depots contained significant concentrations of ANP and TGF-alpha. There was no detectable ACE in the adipocyte fractions, indicating that no contaminating stromal-vascular cells were present in these fractions. These data show significant concentrations of peptides with effects on growth in subfractions of adipose tissue and demonstrate regional differences in concentrations between fat depots.