[The importance of tumor angiogenesis as a prognostic indicator in primary breast cancer]

Recently, the importance of tumor angiogenesis in the process of tumor growth, progression and metastasis in solid tumors has been widely accepted. The prognostic value of angiogenesis has been demonstrated in a variety of solid tumors including breast cancer. In this report, we reviewed recent studies investigating on the value of intratumoral microvessel density (MVD), assessed by a sermiquantitative immunohistochemical assay with using factor-VIII related antibody or anti CD-31 antibody, as a prognostic indicator in primary breast cancer patients. Studies using factor-VIII related antibody showed that the average MVD ranged from 67.3 to 84.0 counts per mm2 area. When used by anti CD-31 monoclonal antibody, the average MVD were 120.3 approximately 135 counts per mm2 area in the range. More than 8 clinical investigations have showed that MVD was a potent prognostic indicator for relapse free survival and/or overall survival in both node-negative and -positive patients. Two reports concluded no prognostic value of MVD, however the average MVD of these two studies significantly differed from other reports. Thus, at present, angiogenesis grade seems to provide an independent prognostic value when the MVD was properly assessed. With respect to the relationship with conventional prognostic indicators, several reports showed the tendency that increased MVD was correlated with younger age and increase of tumor size below 3 cm diameter, however, some reports failed to demonstrate the tendency, suggesting that these correlations are still in controversial. Biological markers including ER, p53 and c-erB2 showed no correlation with the MVD in many studies including our investigation. Only a significant correlation we found was that MVD was increased in tumors with the expression of vascular endothelial growth factor and platelet-derived endothelial cell growth factor, which are noted to be potent endothelial growth factor. Since the evaluation of tumor angiogenesis as a prognostic indicator is now widely investigated in a prospective study, MVD might be introduced to the category of the criteria for determining the schedule of postoperative adjuvant therapy of breast cancer.

Concentrations of vascular endothelial growth factor in the sera of normal controls and cancer patients

Vascular endothelial growth factor (VEGF) is known to play crucial roles in tumor angiogenesis. We have investigated the circulating level of VEGF in sera from cancer patients as well as from healthy normal controls using a sensitive enzymatic immunoassay. Immunoreactive VEGF proteins were detectable in normal sera, and the cutoff level was determined to be 180 pg/ml. In examined patients with all types of cancer, including breast, gastrointestinal, hepatobiliary, and lung cancer, an aberrant increase in the circulating level of VEGF was detected. For example, in 137 primary breast cancer patients, 12 (8.8%) showed an aberrant increase in VEGF levels. This aberrant expression of VEGF in sera was significantly associated with the progression of the disease, and with VEGF protein expression in tumor tissues. In addition, a Western blot analysis confirmed the presence of the VEGF165 form in sera from a patient with recurrent breast cancer. It was concluded that VEGF was detectable in normal sera, and its level was increased in some populations of cancer patients. A positive angiogenesis regulator, VEGF might function as an endocrine growth factor, particularly for solid tumors.

A rare case of ectopic antidiuretic hormone-producing pancreatic adenocarcinoma: new diagnostic approach

We describe a 73-year old man with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) due to an ectopic ADH-producing pancreatic adenocarcinoma. His laboratory findings showed marked hyponatremia, and the water load test showed uncontrolled ADH secretion. The imaging studies revealed pancreatic body cancer. Histological examination revealed an adenocarcinoma of the pancreas, which was positive for ADH immuno-staining. The ADH in the tumor extract was 53.3 pg/g wet weight. In attempt to diagnose ADH-production from the tumor, the ADH in his pancreatic juice was measured and found to be 2.1 pg/ml. We conclude that it is valid to measure the ADH in pancreatic juice to diagnose ectopic ADH production by tumors.

In vitro development of bovine embryos in conditioned media from bovine granulosa cells and vero cells cultured in exogenous protein- and amino acid-free chemically defined human tubal fluid medium

We have investigated the effect of protein- and amino acid-free simple human tubal fluid (HTF) medium conditioned with bovine granulosa cells (BGC) or Vero cells on the development of early bovine embryos to the blastocyst stage. Serum-containing medium (SCM) and serum-free medium (CM) conditioned by BGC (BGC-SCM, BGC-CM) and by Vero cells (VC-SCM, VC-CM) were prepared. Early embryos (1-cell stage and 5- to 8-cell stage) were obtained by in vitro maturation and fertilization of oocytes from slaughtered cows. Embryos were randomly divided into 7 culture groups as follows: culture with BGC-SCM, BGC-CM, VC-SCM, or VC-CM; coculture with BGC or Vero cells; or culture with fresh HTF medium without serum. The proportion of 5- to 8-cell embryos developing to the blastocyst stage in BGC-CM (16%) and VC-CM (12%) was significantly lower (p < 0.05) than in BGC-SCM (41%) and in VC-SCM (29%) and after coculture with BGC (48%) and Vero cells (30%). Similarly, the percentages of 1-cell embryos developing to blastocyst in BGC-CM and VC-CM were significantly lower than in BGC-SCM and VC-SCM and after coculture. Cell numbers per blastocyst developed from 5- to 8-cell embryos in BGC-CM (96.8 cells) and in VC-CM (94.0 cells) were somewhat lower than those in BGC-SCM (128.5 cells) and VC-SCM (117.1 cells) and after coculture with BGC (124.2 cells) and Vero cells (115.3 cells). These results suggest that BGC and Vero cells cultured in a protein- and amino acid-free simple HTF medium synthesize and secrete factor(s) promoting blastocyst formation in vitro. Physiochemical analysis indicated that the embryotrophic substances in BGC-CM were distributed in two molecular size ranges, one between 10 kDa and 30 kDa and another greater than 30 kDa.

Noninvasive evaluation of malignancy of brain tumors with proton MR spectroscopy

PURPOSE

To test clinical proton MR spectroscopy as a noninvasive method for predicting tumor malignancy.

METHODS

Water-suppressed single-voxel point resolved spectroscopy in the frontal white matter of 17 healthy volunteers and 25 patients with brain tumors yielded spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cre), and lactate. These peak intensities were semiquantitated as a ratio to that of the external reference. The validity of the semiquantitation was first evaluated through phantom and volunteer experiments.

RESULTS

The variation in measurements of the designated region in the volunteers was less than 10%. Normal ranges of NAA/reference, Cho/reference, and Cre/reference were 3.59 +/- 0.68, 1.96 +/- 0.66, and 1.53 +/- 0.64 (mean +/- SD), respectively. In 17 gliomas, the Cho/reference value in high-grade gliomas was significantly higher than in low-grade gliomas. Levels of NAA/reference were also significantly different in low-grade and high-grade malignancy. In eight meningiomas (four newly diagnosed and four recurrent), the level of Cho/reference was significantly higher in recurrent meningiomas than in normal white matter or in newly diagnosed meningiomas.

CONCLUSIONS

Higher grades of brain tumors in this study were associated with higher Cho/reference and lower NAA/reference values. These results suggest that clinical proton MR spectroscopy may help predict tumor malignancy.

Deletion mapping of chromosome 10 in human glioma

We analyzed DNAs from 35 gliomas (27 malignant, grades III and IV; 8 less malignant, grades I and II) for loss of heterozygosity (LOH) using microsatellite sequences on chromosome 10 as polymorphic markers. An LOH was found in 8 of 11 (73%) glioblastomas (grade IV) and 4 of 16 (25%) grade III gliomas, but not in the less malignant types. We detected three commonly deleted regions. One was located in a telomeric region of 10p and the others were relatively large regions of 10q. Our results suggested that three putative tumor suppressor genes on chromosome 10 are involved in the malignant progression of gliomas.

Quantitative analysis of vascular endothelial growth factor in primary breast cancer

BACKGROUND

Recent clinical studies have demonstrated that tumor angiogenesis is a potent prognostic indicator for breast cancer patients. The quantitation of endothelial growth factors is thought to be useful to assess angiogenic phenotype in the tumor. Among the many new endothelial growth factors, vascular endothelial growth factor (VEGF) is known to be particularly responsible for promoting the neovascularization in human breast cancer.

METHODS

Intratumoral protein levels of VEGF were measured by enzymatic immunoassay in 135 primary breast cancer tissues. The VEGF levels were compared with the microvessel density evaluated by immunostaining the endothelial antigen and also were compared with intratumoral protein levels of other endothelial growth factors, including basic fibroblast growth factor (bFGF) and hepatocyte growth factor (HGF).

RESULTS

Intratumoral VEGF concentrations varied from 3.3 pg/mg protein to 2032 pg/mg protein (average 148 pg/mg protein). An immunocytochemical analysis using anti-VEGF antibody confirmed that VEGF was located mainly in the cytoplasm of the tumor cells. The VEGF concentrations were significantly higher in vascularly rich tumors than in vascularly poor tumors. No significant association was found between VEGF concentrations and the two other endothelial growth factor concentrations.

CONCLUSIONS

The quantitation of intratumoral VFGF levels seems to be useful for assessing the activity of tumor angiogenesis.

Regulation of endothelial growth factor expressions in breast cancer

Expression of various endothelial growth factors including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), Platelet-derived endothelial cell growth factor (PD-ECGF) and hepatocyte growth factor (HGF) was investigated in human breast carcinoma tissues, and the results were compared to the intratumoral microvessel density evaluated by the immunostaining to anti-factor VIII related antigen. VEGF and PD-ECGF were examined by immunostainings, and bFGF and HGF were assessed by enzymatic immunoassays. As a result, VEGF and PD-ECGF were significantly associated with the increment of microvessel density, although no significant correlation was found with bFGF and HGF. In addition, interestingly, a tendency of co-expression between VEGF and PD-ECGF was demonstrated. It was suggested that VEGF and PD-ECGF play important roles in the promotion of angiogenesis in human breast cancer.

Intraoperative radiation therapy and chemotherapy for huge choroid plexus carcinoma in an infant--case report

A 2-month-old boy presented with a huge choroid plexus carcinoma in the left cerebral hemisphere. Almost total resection of the tumor was achieved, but a remnant abruptly enlarged 5 months later, requiring reoperation. After radical resection of the tumor, intraoperative radiation (10 Gy) was delivered. Postoperative chemotherapy was performed with methotrexate and vincristine, selected on the basis of in vitro chemosensitivity testing. No recurrence of the tumor was detected 18 months after the second operation. Radical surgery with these adjuvant therapies may be a good method to control this aggressive disease in infants.

A new in vitro model of specific targeting therapy of cancer: retargeting of PWM-LAK cells with bispecific antibodies greatly enhances cytotoxicity to hepatocellular carcinoma

For the purpose of establishing a new in vitro model of adoptive immunotherapy, we synthesized two kinds of bispecific antibodies (BsAbs), i.e., (OK x L) BsAbs constructed with both OKT-3 (anti-CD3) and L-7-6 (anti-HCC), and (3G x L) BsAbs constructed with 3-G-8 (anti-CD16) and L-7-6 antibodies. These two BsAbs, having pairs of binding arms on their single molecule, showed similar binding to target cells as the parental monoclonal antibodies (OKT-3, 3-G-8 and L-7-6), when examined with FACS. Newly devised in vitro cytotoxicity tests revealed that LAK or PWM-stimulated LAK (PWM-LAK) cells did not show any significant cytotoxic activity to HCC cells, while both effector cells equally showed greatly enhanced cytotoxicity to HCC even at a low effector/target (0.3) in the presence of BsAbs (OK x L) for the efficient retargeting of the effector cells. Inasmuch as PWM-LAK cells proliferate in vitro 3-5 times faster than LAK cells, adoptive immunotherapy using PWM-LAK cells in combination with (OK x L) BsAbs should be very promising.

[Follow-up study of vestibular neuronitis]

A follow-up study of 26 patients with vestibular neuronitis is reported. The disease is characterized by an acute attack of severe vertigo with complete loss of unilateral caloric response. The following results were obtained: 1) The average period of spontaneous nystagmus was 136 days and the standard error was 39 days. 2) No correlation could be found between age and the period of spontaneous nystagmus. 3) Six patients showed direction reversal in their spontaneous nystagmus (recovery nystagmus), and their outcome was good. 4) On the most recent caloric test, 42% of the patients had bilateral normal responses, 27% displayed partial improvement on the affected side, and no reaction was observed in 31% of patients. We suggest that three types of clinical courses may occur in vestibular neuronitis: i) complete recovery of the function of the affected vestibular nerve, ii) partial recovery of vestibular function, and iii) no recovery of the affected vestibular nerve, but central nervous system compensates for the vestibular imbalance.

Management of pilocytic astrocytoma

Pilocytic astrocytoma, when totally resected, has a favorable outcome compared to other astrocytomas. However, when residual tumor remains, the prognosis is less satisfactory. Our study addressed the issues of prognosis in cases of residual tumor and the effect of post-surgical radiation therapy on tumor recurrence. We analyzed 41 cases of pilocytic astrocytoma which were diagnosed by histologic examination. Twenty-six patients were 15 years old or younger, and 15 patients were 16 years old or older. An analysis of the relationship between age and tumor location revealed a cerebellar predominance in both age groups; however, there were more brain stem and basal ganglia tumors among adults. Overall prognosis was favorable, with a 2-year survival rate of 97.6%, 94.6% at 5 years, and 94.6% at 10 years. Children had a better prognosis than adults due to more favorable tumor location. Gross total resection resulted in the best prognosis, i.e., no recurrence during a 10-year follow-up period. Radiation treatment after surgery suppressed residual tumor. We concluded that the best treatment for pilocytic astrocytoma is: 1) total resection, if possible, followed by 2) irradiation of any residual tumor to suppress recurrence.

Transcingulate approach to lateral ventricle tumors. Technical case report

Surgical experience with treatment of two lateral ventricle tumors using the anterior transcingulate approach demonstrate that this route provides an excellent approach to tumors attached to the lateral wall of the anterior ventricle, without causing gross neurologic deficits. This approach deserves attention as an alternative to the transcallosal approach in selected patients.

Blood pressure sensitivity to salt, calcium metabolism and insulin sensitivity in essential hypertension

1. To reveal the mechanism responsible for the increase in blood pressure (BP) response to high salt intake in salt-sensitive essential hypertensives, pressor responses to angiotensin II and norepinephrine on high and low salt diet, influence of high salt intake on calcium metabolism and insulin sensitivity were studied in essential hypertensive and in normotensive subjects with or without family history of hypertension. 2. Pressor responses to angiotensin II and norepinephrine were significantly increased in salt-sensitive essential hypertensives irrespective of high or low salt diet. 3. In normotensive subjects with positive family history, high salt diet elevated BP in association with an increase in urinary calcium excretion. This observation, however, was not shared by the normotensive subjects with negative family history of hypertension. In the normotensive subjects with positive family history of hypertension, the cytosolic calcium concentration in platelets was significantly higher than in those with negative family history. A significant correlation between the cytosolic calcium concentration and elevation of BP was also observed. 4. In normotensive subjects with family history of hypertension, insulin sensitivity was decreased and correlated negatively with the cytosolic calcium concentration. 5. These results suggest that in salt-sensitive essential hypertensives increased pressor responses to angiotensin and norepinephrine and elevation of BP as well as insulin resistance may result from inherited abnormalities of intracellular calcium metabolism.

Effects of enalapril on left ventricular mass and diastolic function in essential hypertension: special reference to duration of hypertension

Using M-mode and pulsed Doppler echocardiography, the effects of enalapril on left ventricular (LV) hypertrophy and diastolic dysfunction in essential hypertension and the relation between improvement in these two parameters and duration of hypertension were evaluated. The subjects, 30 previously untreated hypertensive patients, were divided into nonhypertrophy (18 patients) and hypertrophy (12 patients) groups. All patients received enalapril at a daily dose of 5 to 10 mg for 6 months. Left ventricular mass by M-mode echocardiography and LV inflow (LVIF) velocity by transthoracic pulsed Doppler echocardiography were measured before and after enalapril therapy. In the nonhypertrophy group, enalapril significantly increased peak early diastolic LVIF (E) velocity (P < .05), slightly lowered peak atrial systolic LVIF (A) velocity, significantly decreased their ratio (A/E) (P < .01), and significantly shortened both the deceleration time, from the peak of the early diastolic wave, and isovolumic relaxation time (P < .05 and P < .01, respectively). In the hypertrophy group, enalapril significantly increased E (P < .05), slightly lowered A, significantly decreased A/E (P < .05), slightly shortened the deceleration time and isovolumic relaxation time, and slightly decreased LV mass. The administration of enalapril correlated significantly and positively with the duration of hypertension and the rates of change in A/E and LV mass in all of the hypertensive patients (P < .01 and P < .05, respectively). These results suggest that long-term administration of enalapril to hypertensive patients improves LV diastolic hemodynamics regardless of the presence or absence of LV hypertrophy and that the effects are most remarkable in patients with the shortest duration of hypertension.

Volume-sensitive chloride channel activity does not depend on endogenous P-glycoprotein

To determine whether endogenous P-glycoprotein, the MDR1 gene product that functions as a drug transport pump, is a volume-sensitive Cl- channel molecule or a protein kinase C-mediated regulator of the Cl- channel, whole-cell patch-clamp and molecular biological experiments were carried out in a human small intestinal epithelial cell line. Endogenous expression of P-glycoprotein was confirmed by Northern blot analysis, reverse transcription-polymerase chain reaction, Western blot analysis, and immunostaining. The P-glycoprotein expression was abolished by the antisense (but not sense) oligonucleotide for the MDR1 gene, whereas the magnitude of the Cl- current activated by osmotic swelling was not distinguishable between both antisense- and sense-treated cells. The volume-sensitive Cl- currents were not specifically affected by the anti-P-glycoprotein monoclonal antibodies, MRK16, C219, and UIC2. An inhibitor of P-glycoprotein-mediated pump activity, verapamil, was found to never affect the Cl- current. A substrate for the P-glycoprotein-mediated drug pump, vincristine or daunomycin, did not prevent swelling-induced activation of the Cl- current. Furthermore, the Cl- current was not affected by an activator of protein kinase C (12-O-tetradecanoylphorbol-13-acetate or 1-oleoyl-2-acetyl-sn-glycerol). Thus, it is concluded that the endogenous P-glycoprotein molecule is not itself a volume-sensitive Cl- channel nor a protein kinase C-mediated regulator of the channel in the human epithelial cells.

Anaplastic ependymomas: clinical features and tumour suppressor gene p53 analysis

We analyzed seven cases of anaplastic ependymoma, focusing on neuro-imaging, histopathology, and mutations of the tumour suppressor gene p53. Five of the seven tumours were supratentorial. All had both cystic and solid components, with fragment calcifications detectable on CT scan. The solid parts of the tumours were imaged as heterogenous hypo- or iso-intense areas with moderate enhancement on T1-weighted magnetic resonance images. Vascularity was not prominent on angiograms except for one case. Histologically, in addition to the WHO criteria, loss of typical cellular architecture, endothelial proliferation, and necrosis were commonly found. A mutation in Exon 5 of the tumour suppressor gene p53 was detected in one anaplastic ependymoma out of five tumours (two benign and three anaplastic ependymomas) examined by PCR-SSPC analysis of genomic DNA followed by direct sequencing. Anaplastic ependymoma typically presents as a calcified cystic tumour in the supratentorial parenchyma or transependyma. Mutations of p53 deserve further investigation to examine their possible role in the oncogenesis and malignant transformation of ependymoma.

Spinous process-splitting laminoplasty with an extended foraminotomy for cervical myelopathy

We present the surgical results of a laminoplasty with an extended foraminotomy for cervical myelopathy. We chose spinous process-splitting laminoplasty, because it gave us the opportunity to perform bilateral foraminotomies through the same exposure. An extended foraminotomy means that root decompression is performed as far laterally as possible, using the surgical microscope. We performed this method in 18 patients and experienced favorable clinical results. Neuroradiological evaluations revealed good decompression of the spinal cord postoperatively. Although the operation time needed was longer compared with the original method, the average blood loss was 430 ml and blood transfusion was necessary in five patients. This method can be considered when cervical myelopathy is treated by a posterior approach.

Serum concentrations of hepatocyte growth factor in breast cancer patients

Hepatocyte growth factor (HGF) was first identified as a potent stimulator of hepatocyte growth and DNA synthesis. Later, it was shown that HGF can promote cell motility and cell proliferation in various types of cells, including tumor cells and endothelial cells. We have examined serum concentrations of HGF in breast cancer patients using an ELISA. Of 134 primary breast cancer patients, 49 (36.6%) showed a significant increase in the circulating level of HGF as compared to healthy controls. The increase in the HGF level was significantly associated with axillary lymph node metastases and histological evidence of venous invasion. No significant correlation between serum HGF concentrations and intratumoral HGF concentrations was found; however, the removal of the primary tumor clearly decreased the serum HGF level, suggesting that the elevation of HGF in the serum was tumor related. Twenty-nine (82.9%) of 35 patients with recurrent breast cancer had an increase in the serum HGF level. The HGF level was significantly higher in patients with liver metastases compared to those with other sites of metastases. Postoperative sequential examinations confirmed that the increase in the serum HGF level was associated with the appearance of relapse. In conclusion, the serum HGF level was significantly increased in breast cancer patients. Circulating HGF might play important roles in tumor progression in this malignancy.

Vascular endothelial growth factor and platelet-derived endothelial cell growth factor are frequently coexpressed in highly vascularized human breast cancer

Vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) are known to be angiogenic growth factors in vitro and in vivo. In this study, we have investigated the relationship between VEGF expression and PD-ECGF expression in human breast cancer tissues using immunocytochemical methods. Of 152 primary breast cancers, 84 (55.3%) and 71 (46.7%) were positive for VEGF and PD-ECGF, respectively. Fifty-three (63. 1%) of 84 VEGF-positive tumors had a PD-ECGF-positive phenotype, whereas only 18 (26.5%) of 68 VEGF-negative tumors had a PD-ECGF-positive phenotype. There was a significant correlation between the VEGF expression and PD-ECGF expression (P < 0.01). As a single factor, VEGF expression and PD-ECGF expression were significantly associated with an increase in the microvessel density assessed by the immunocytochemical analysis using antifactor VIII-related antigen mAb. Interestingly, in addition, of 53 tumors with more than 100 microvessel counts/1 mm2, 40 (75.5%) had both VEGF- and PD-ECGF-positive phenotypes. It was found that VEGF and PD-ECGF were frequently coexpressed in highly vascularized tumors with high microvessel counts. It is suggested that VEGF and PD-ECGF might cooperatively function in the neovascularization of human breast cancer.

Effects of medroxyprogesterone acetate therapy on advanced or recurrent breast cancer and its influences on blood coagulation and the fibrinolytic system

The effects of medroxyprogesterone acetate (MPA) therapy on advanced or recurrent breast cancer and its influence on blood coagulation and the fibrinolytic system were compared among three different therapy regimens consisting of cyclophosphamide, adriamycin, and 5-fluorouracil (CAF) + MPA and CAF or MPA alone. A clinical response was observed in 42.9% (9/21) of the patients for CAF + MPA, 36.4% (8/22) for CAF and 23.8% (5/21) for MPA alone. No marked thrombosis or its prodromal condition was observed in any group. The effects on the test values for blood coagulation and the fibrinolytic system did not significantly change in the CAF group. However, both AT-III and protein C significantly increased above the normal ranges in the CAF+MPA and MPA groups. Increases in factor X, plasminogen, and alpha 2-plasmin inhibitor/plasmin complex (PIC) and decreases in fibrinogen, tissue plasminogen activator, and D-dimer, were all observed in the MPA and CAF + MPA groups, especially in the MPA group, although these changes remained within the normal ranges. The data indicated that MPA has various influences on blood coagulation and the fibrinolytic system, but these changes did not suggest activation of the blood coagulation system.

Divergent effects of gonadotrophin-releasing hormone (GnRH) analogue and authentic GnRH on the anterior pituitary gland of rats with restricted feeding

The effects of gonadotrophin-releasing hormone analogue (GnRHa; buserelin) on the pituitary function and morphology of food-restricted rats were compared with those of authentic GnRH. After adult female rats had been restricted to 10 g food/day for 60 days, various doses of GnRHa (10 ng, 100 ng and 1 microgram) or GnRH (10 micrograms) were administered either daily for 7 days or twice a week for 4 weeks from day 61 of the period of underfeeding. Underfeeding brought about a decrease in the pituitary gonadotrophin content, serum levels of gonadotrophins and oestradiol, and the number and size of both LH- and FSH-positive pituitary cells. Daily and/or twice-weekly administration of authentic GnRH to underfed rats produced an increase in pituitary and serum gonadotrophin levels and the number and size of both LH- and FSH-positive pituitary cells. The administration of GnRHa daily for 7 days increased serum gonadotrophin levels, while it produced a reduction in the pituitary gonadotrophin content and number and size of both LH- and FSH-positive pituitary cells in a dose-dependent manner. Twice-weekly administration of GnRHa also produced an elevation of serum gonadotrophin levels and reduction of pituitary gonadotrophin content, although it did not affect the numbers and areas of LH- and FSH-positive pituitary cells. A GnRH loading test performed after the GnRHa treatment showed that the GnRHa treatment performed in this study did not produce down-regulation of the GnRH receptor. Thus, it can be concluded that the gonadotrophin-synthesizing activity of GnRHa is weaker than that of authentic GnRH, or that GnRHa may preferentially exert gonadotrophin-releasing activity rather than gonadotrophin-synthesizing activity in the anterior pituitary of underfed rats.