The Herbal Medicine Unkei-To Stimulates Cytokine-Induced Neutrophil Chemoattractant Production in the Pituitary Folliculo-Stellate—Like Cell Line (TtT/GF)

PROBLEM: We previously reported that a cytokine-induced neutrophil chemoattractant (CINC) was produced in the pituitary gland and that it influenced anterior pituitary hormone release. In this study we investigated the effect of Unkei-to, a Japanese herbal medicine, on CINC production in the rat anterior pituitary gland and the pituitary folliculo-stellate-like cell line (TtT/GF). METHOD OF STUDY: Dispersed normal anterior pituitary cells and the folliculo-stellate-like cell line TtT/GF were used to test the effect of Unkei-to on CINC secretion and CINC mRNA accumulation. Concentrations of CINC in the conditioned media were measured by an enzyme-linked immunosorbent assay, and levels of CINC mRNA were analyzed by Northern blot analysis. RESULTS: Unkei-to (20 μg/ml) significantly increased the secretion of CINC by normal anterior pituitary cells within 12 hr of incubation. Unkei-to also stimulated CINC secretion from TtT/GF cells in a time- and dose-dependent manner. Unkei-to (20 μg/ml) increased CINC mRNA accumulation in TtT/GF cells within 3 hr of incubation and also caused a 13-fold increase in the secretion of CINC from TtT/GF cells compared with the vehicle group within 24 hr of incubation. Finally, we found that some of the Unkei-to's ingredients, Evodiae fructus and Pinelliae tuber, markedly stimulated CINC secretion from TtT/GF cells. CONCLUSIONS: Our results will help to elucidate the mechanism behind the clinical effect of Unkei-to on the anterior pituitary gland. They also suggested the presence of special substances, which stimulate CINC secretion, within Unkei-to's ingredients such as E. fructus and P. tuber.     

Pituitary Folliculo-Stellate-Like Cells Stimulate Somatotroic Pituitary Tumor Growth in Nude Mice

A new cell line (TtT/GF) established from a murine pituitary thyrotropic tumor having characteristics similar to those of pituitary folliculo-stellate cell (FS cell) was implanted into nude mice together with cells from a rat pituitary somatotrophic tumor cell line (MtT/S) to determine whether the former enhances pituitary tumor growth. For as long as 2-3 mo after implantation, MtT/S cells implanted either alone or together with fibroblasts formed either no tumors or only very small tumors in the nude mice. In contrast all of the nude mice that had received MtT/S cells implanted together with TtT/GF cells developed large tumors. Furthermore, the mice bearing the MtT/S and TtT/GF implants showed a significantly higher body weight and serum growth hormone level than those bearing only MtT/S cells or a combination of MtT/S cells and fibroblasts. The TtT/GF cell line itself had no tumorigenicity during the experimental period. Therefore, the TtT/GF cell line as a model of FS cells enhanced pituitary endocrine cell tumor formation. Additionally, immunocytochemistry showed that TtT/GF cells positive for glial fibrillary acidic protein (GFAP) or S-100 protein were present in the parenchymatous tissue elements or connective tissue surrounding the tumor nests. In the parenchymatous tissue, the TtT/GF cells exhibited a stellate appearance and surrounded neighboring tumor cells with their long cell processes. These results suggest that TtT/GF cells can serve as a model for pituitary FS cells, and are capable of stimulating pituitary tumor growth either by modifying the microenvironment or producing growth factors.     

The herbal medicine Unkei-to stimulates the secretion of a cytokine-induced neutrophil chemoattractant,CINC/gro,in the rat ovarian cell culture

PROBLEM AND METHOD OF STUDY: We investigated the ovulation-inducing effects of Unkei-to, a Japanese herbal medicine, in relation to the production of sex steroid hormones (17beta-estradiol and progesterone), cytokine-induced neutrophil chemoattractant (CINC/gro), interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) in the rat ovarian cell culture. RESULTS: Unkei-to at a concentration of 100 microg/mL significantly stimulated the secretions of 17beta-estradiol and progesterone (P < 0.01) in cultured whole ovarian dispersates. Unkei-to also enhanced the secretion of CINC/gro in a dose-dependent manner, and the secretions of CINC/gro increased significantly at concentrations of 10 and 100 microg/mL (P < 0.01). These stimulatory effects of Unkei-to on steroidgenesis and CINC/gro production are very similar to those of another Japanese herbal medicine, Toki-Shakuyaku-san. In addition, Unkei-to significantly (P < 0.01) enhanced the secretions of both IL-1beta and TNF-alpha, which are known to stimulate the secretion of CINC/gro in the ovulatory process, at concentrations of 10 and 100 microg/mL. The stimulatory effect of Unkei-to at a concentration of 100 microg/mL on IL-1beta/was significantly (P < 0.01) lower than that of Toki-Shakuyaku-san, while the stimulatory effects of these two herbal medicines at a concentration of 100 microg/mL on TNF-alpha were similar. CONCLUSIONS: These results show that Unkei-to can stimulate ovarian steroidgenesis and the ovulatory process by inducing the secretion of CINC/gro with IL-1beta and TNF-alpha in vitro. Unkei-to has stimulatory effects on both steroidgenesis and the ovulatory process in the ovary as well as a stimulatory effect on the hypothalamus-pituitary axis, and it may be useful for treating patients with ovulatory disorders.     

Percoll density gradient-enriched populations of rat pituitary cells: Interleukin 6 secretion, proliferative activity, and nitric oxide synthase expression

We used a discontinuous Percoll density gradient centrifugation to prepare enriched populations of prolactin (PRL), growth hormone (GH), and folliculo-stellate (FS) cells from rat anterior pituitaries in order to characterize these various cell populations. After cell dissociation and centrifugation, enriched PRL cells (55% of total cells as determined by immunocytochemistry [ICC]) were present in Fraction 1 (Fr1) (density ([d])=1.059). Fr2 (d=1.071) had enriched S100-positive FS cells (31% of total cells), but enriched GH cell (60% of total cells) were present in Fr3 (d=1.094). Interleukin 6 (IL-6) was secreted mainly by enriched PRL cells in Fr1 (350 pg/mL/10⁶ cells) and Fr2 (194 pg/mL/10⁶ cells), and much less by the enriched GH cells in Fr3 (16 pg/mL/10⁶). Proliferation studies with combined³H-thymidine and ICC for pituitary hormones showed that only the PRL cell had significant proliferative activity. Immunostaining showed that immediately after separation, all three isoforms of nitric oxide synthase (NOS) were expressed in anterior pituitary cells. After 3 d of culture, there was a marked increase in nuclear staining for neuronal NOS (nNOS) in all three fractions, whereas inducible NOS (iNOS) and endothelial NOS (eNOS) expression did not change significantly. These results indicate that:

Reassembly of Anterior Pituitary Organization by Hanging Drop Three-Dimensional Cell Culture

The anterior pituitary gland comprises 5 types of hormone-producing cells and non-endocrine cells, such as folliculostellate (FS) cells. The cells form a lobular structure surrounded by extracellular matrix (ECM) but are not randomly distributed in each lobule; hormone-producing cells have affinities for specific cell types (topographic affinity), and FS cells form a homotypic meshwork. To determine whether this cell and ECM organization can be reproduced in vitro, we developed a 3-dimensional (3D) model that utilizes hanging drop cell culture. We found that the topographic affinities of hormone-producing cells were indeed maintained (ie, GH to ACTH cells, GH to TSH cells, PRL to LH/FSH cells). Fine structures in hormone-producing cells retained their normal appearance. In addition, FS cells displayed well-developed cytoplasmic protrusions, which interconnected with adjacent FS cells to form a 3D meshwork. In addition, reassembly of gap junctions and pseudofollicles among FS cells was observed in cell aggregates. Major ECM components—collagens and laminin—were deposited and distributed around the cells. In sum, the dissociated anterior pituitary cells largely maintained their in vivo anterior pituitary architectures. This culture system appears to be a powerful experimental tool for detailed analysis of anterior pituitary cell organization.     

Clear-Cell Follicular Adenoma of Ectopic Thyroid in the Submandibular Region

We used a discontinuous Percoll density gradient centrifugation to prepare enriched populations of prolactin (PRL), growth hormone (GH), and folliculo-stellate (FS) cells from rat anterior pituitaries in order to characterize these various cell populations. After cell dissociation and centrifugation, enriched PRL cells (55% of total cells as determined by immunocytochemistry [ICC] were present in Fraction 1 (Fr1) (density ([d]) = 1.059). Fr2 (d=1.071) had enriched S100-positive FS cells (31% of total cells), but enriched GH cell (60% of total cells) were present in Fr3 (d=1.094). Interleukin 6 (IL-6) was secreted mainly by enriched PRL cells in Fr1 (350 pg/mL/106 cells) and Fr2 (194 pg/mL/106 cells), and much less by the enriched GH cells inFr3 (16 pg/mL/106). Proliferation studies with combined 3H-thymidine and ICC for pituitary hormones showed that only the PRL cell had significant prolifereative activity. Immunostaining showed that immediately after separation, all three isoforms of nitric oxide synthase (NOS) were expressed anterior pituitary cells. After 3 d of culture, there was a marked increase in nuclear staining for neuronal NOS (nNOS) in all three fractions, whereas inducible NOS (iNOS) and endothelial NOS (eNOS) rexpression did not change significantly. These results indicate that: 1. Enriched populations of PRL, FS, and GH pituitary cells can be readily obtained with a rapid discontinuous percoll density separation procedure. 2. PRL cells from different fractions of the gradient show differenet proliferation rates and IL-6 secretion varied in different enriched cell populations. 3. Although all three isoforms of NOS were expressed in rat pituitary cells, nNOS is the prindipal isoform in anterior pituitary cells, and its expression was icreased after 3 d of culture of anterior pitutuitary cells.     

TGF-B and Estrogen Regulate P27(Kip1) and Cyclin D(1) in Normal and Neoplastic Rat Pituitary Cells

Pituitary hyperplasia and tumor growth are regulated by various hormones and growth factors. Estrogen (E₂) stimulates pituitary cell proliferation and prolactin (PRL) production. Estrogen also regulates transforming growth factor-β (TGF-β) effects in the pituitary. TGF-β in turn regulates various cell cycle proteins including p15 and p27^Kip1 (p27). To better understand the regulatory role of growth factors and hormones in the cell cycle we analyzed cyclin D₁, cyclin E, and p27 expression in normal and neoplastic rat pituitary cells. An in vitro analysis using cultured normal pituitary cells and GH₃ tumor cells and an in vivo analysis of estrogen-treated normal pituitary and implanted GH₃ cells were performed. Semiquantitative RT-PCR was used to analyze mRNA expression for cyclin D₁, cyclin E, and p27 in cultured pituitary cells and E₂-treated pituitaries in vivo. Cyclin D₁ and p27 were localized in the nuclei of normal pituitary cells by immunocytochemistry (ICC). Very weak or absent immunostaining for cyclin D₁ and p27 was present in GH₃ cells. Both normal pituitary and GH₃ cells had strong nuclear staining for cyclin E. Normal pituitary had a 20-fold greater amount of cyclin D₁ mRNA and a 3-fold greater amount of p27 mRNA compared to GH₃ cells, whereas GH₃ cells had slightly (1.5-fold) more cyclin E than normal pituitary cells. E₂ treatment in vivo stimulated cell proliferation and decreased cyclin D₁ mRNA levels in normal pituitary. GH₃ tumor cells, implanted subcutaneously in the same animal, showed increased proliferation after E₂ treatment, but there was no change in cyclin D₁ mRNA in GH₃ cells. Cyclin E and p27 mRNA levels did not change significantly in normal pituitary or in GH₃ cells after E₂ treatment in vivo. Treatment of normal pituitary cells with 10⁻⁹ M TGF-β1 for 3 d in vitro led to significant decreases in cyclin D₁ and p27 mRNAs (p < 0.05), whereas cyclin E levels were unchanged. These results indicate that cyclin D₁ and p27 mRNAs are present at significantly higher levels in normal pituitary compared to GH₃ cells, and that both E₂ and TGF-β1 can downregulate cyclin D₁ mRNA levels in normal pituitary cells, suggesting that these factors regulate G1 to S phase transition in pituitary cells. The lower levels of specific cell cycle regulators in GH₃ cells may explain the decreased regulatory control by E₂ in GH₃ tumor cells.     

DNA Methylation Regulates p27Kip1 Expression in Rodent Pituitary Cell Lines

We previously reported loss of expression of p27^Kip1 (p27) protein in rat GH₃ and mouse GHRH-CL1 pituitary tumor cells compared with normal pituitary (NP). The molecular basis for the loss of expression of p27 protein in GH₃ and GHRH-CL1 cells is unknown. To determine the role of p27 gene methylation in the regulation of the expression of this cell cycle protein, the methylation patterns of p27 in normal and neoplastic pituitary cells was analyzed. Inhibition of DNA methyltransferase (DNA-MTase) with 5-aza-2′-deoxycytidine (AZAdC) induced expression of both p27 protein and mRNA when GH₃ and GHRH-CL1 cells were treated for 7 days in vitro. DNA methylation correlated inversely with the expression of p27 gene products in NP and pituitary tumor cell lines. Bisulfite genomic sequencing analysis showed that the normally unmethylated cytosines in exon 1 in NP and AtT20 cells were extensively methylated in GH₃ and GHRH-CL1 cells. After treatment of GH₃ and GHRH-CL1 cells with 10 μmol/L AZAdC, there were decreased numbers of methylated cytosines (by 60% to 90%) with variable methylation patterns observed by bisulfite genomic sequencing. Analysis of genomic DNA with methylation-sensitive enzymes showed that all SmaI, HhaI, and AvaI enzyme sites of the p27 gene in exon 1 were methylated in GH₃ cells but not in NP, confirming the bisulfite genomic sequencing results. AtT20 cells and a human pituitary null cell adenoma cell line (HP75), which expressed abundant p27, had a methylation pattern similar to the NP. DNA-MTase activity was elevated fourfold in GH₃ cells and twofold in GHRH-CL1 cells compared with DNA-MTase activity in NP and AtT20 cells. These results suggest that increased DNA methylation is another mechanism of silencing of the p27 gene in some pituitary tumors and possibly in other types of neoplasms.     

Change in Somatostatinergic Tone of Acromegalic Patients according to the Size of Growth Hormone-Producing Pituitary Tumors

The aim of this study was to investigate the relationship between somatostatinergic tone (SST) and the size of growth hormone (GH)-producing pituitary tumors. GH levels of 29 patients with newly diagnosed acromegaly were measured using a 75-gram oral glucose tolerance test (OGTT), an insulin tolerance test (ITT), and an octreotide suppression test (OST). Differences between GH levels during the ITT and the OGTT (ΔGH_IO), and between the OGTT and the OST at the same time point (ΔGH_OS) were compared according to the size of the tumor and the response pattern to the OST. ΔGH_IO of macroadenomas (n=22) was non-significantly higher than those of microadenomas while ΔGH_OS of macroadenomas were significantly higher than those of microadenomas. According to further analyses of macroadenomas based on the response pattern to the OST, GH levels during the ITT were significantly higher in non-responders. ΔGH_OS showed near-significant differences between responders and non-responders. In conclusion, as the size of the pituitary tumor increases, the effect of glucose on SST appears to be attenuated. Macroadenomas that are non-responders to the OST possess a portion of GH secretion exceeding the range of regulation by SST.     

Demonstration of an inwardly rectifying K+ current component modulated by thyrotropin-releasing hormone and caffeine in GH3 rat anterior pituitary cells

 Reduction of an inwardly rectifying K⁺ current by thyrotropin-releasing hormone (TRH) and caffeine has been considered to be an important determinant of electrical activity increases in GH₃ rat anterior pituitary cells. However, the existence of an inwardly rectifying K⁺ current component was recently regarded as a misidentification of an M-like outward current, proposed to be the TRH target in pituitary cells, including GH₃ cells. In this report, an inwardly rectifying component of K⁺ current is indeed demonstrated in perforated-patch voltage-clamped GH₃ cells. The degree of rectification varied from cell to cell, but both TRH and caffeine specifically blocked a fraction of current with strong rectification in the hyperpolarizing direction. Use of ramp pulses to continuously modify the membrane potential demonstrated a prominent blockade even in cells with no current reduction at voltages at which M-currents are active. Depolarization steps to positive voltages at the maximum of the inward current induced a caffeine-sensitive instantaneous outward current followed by a single exponential decay. The magnitude of this current was modified in a biphasic way according to the duration of the previous hyperpolarization step. The kinetic characteristics of the current are compatible with the possibility that removal from inactivation of a fast-inactivating delayed rectifier causes the hyperpolarization-induced current. Furthermore, the inwardly rectifying current was blocked by astemizole, a potent and selective inhibitor of human ether-á-go-go -related gene (HERG) K⁺ channels. Along with other pharmacological and kinetic evidence, this indicates that the secretagogue-regulated current is probably mediated by a HERG-like K⁺ channel. Addition of astemizole to current-clamped cells induced clear increases in the frequency of action potential production. Thus, an inwardly-rectifying K⁺ current and not an M-like outward current seems to be involved in TRH and caffeine modulation of electrical activity in GH₃ cells. Received: 15 May 1997 / Received after revision and accepted: 24 July 1997     

Aberrant DNA methylation of cyclin D2 and p27 genes in rodent pituitary tumor cell lines correlates with specific gene expression

We previously reported that increased DNA methylation was an important mechanism of silencing the p27 gene in some pituitary tumor cell lines [1]. DNA methylation correlated inversely with p27 gene expression. The p27 and cyclin D2 genes are located in the same region of mouse chromosome 6, rat chromosome 4, and human chromosome 12p13. Because both genes are located in the same gene cluster, we investigated whether methylation was a principal mechanism regulating cyclin D2 as well as p27 expression in rodent pituitary cell lines. Bisulfite genomic sequencing showed that the normally unmethylated cytosines of the p27 gene in normal pituitary (NP) were extensively methylated in GH3 and GHRH-CL1 cells, but not in AtT 20, αT₃-1 and LβT₂ cells; but cyclin D2 was extensively inactivated in various pituitary tumor cell lines by increased DNA methylation. These abnormalities of methylation in p27 and cyclin D2 genes occurred with different frequencies in five pituitary tumor cell lines with 100% (5/5) methylation of the cyclin D2 gene and 40% (2/5) methylation of the p27 gene. Treatment with the methyl transferase inhibitor 5′-aza-2′-deoxycytidine (AZAdC) increased expression of cyclin D2 and p27 in GH3 and GHRH-CL1 pituitary tumor cells. There was a correlation between hypermethylation and gene expression. GH₃ tumors implanted into Wistar-Furth rats in vivo did not change the methylation status of the p27 and cyclin D2 genes. These data indicate a coordinately reduced expression of these two linked genes in most rodent pituitary tumor cell lines and suggest that methylation of cyclin D2 and p27 might occur in a “hot spot” in this gene-rich cluster. Supported in part by NIH CA 37231 and CA 42951     

Cell type influences the molecular mechanisms involved in hormonal regulation of ERG K<Superscript>+</Superscript> channels

While the thyrotropin-releasing hormone (TRH) effect of raising intracellular Ca²⁺ levels has been shown to rely on G_q/11 and PLC activation, the molecular mechanisms involved in the regulation of ERG K⁺ channels by TRH are still partially unknown. We have analysed the effects of βγ scavengers, Akt/PKB inactivation, and TRH receptor (TRH-R) overexpression on such regulation in native and heterologous expression cell systems. In native rat pituitary GH₃ cells β-ARK/CT, Gα_t, and phosducin significantly reduced TRH inhibition of rERG currents, whereas in HEK-H36/T1 cells permanently expressing TRH-R and hERG, neither of the βγ scavengers affected the TRH-induced shift in V _1/2. Use of specific siRNAs to knock Akt/PKB expression down abolished the TRH effect on HEK-H36/T1 cell hERG, but not on rERG from GH₃ cells. Indeed, wortmannin or long insulin pretreatment also blocked TRH regulation of ERG currents in HEK-H36/T1 but not in GH₃ cells. To determine whether these differences could be related to the amount of TRH-Rs in the cell, we studied the TRH concentration dependence of the Ca²⁺ and ERG responses in GH₃ cells overexpressing the receptors. The data indicated that independent of the receptor number additional cellular factor(s) contribute differently to couple the TRH-R to hERG channel modulation in HEK-H36/T1 cells. We conclude that regulation of ERG currents by TRH and its receptor is transduced in GH₃ and HEK-H36/T1 cell systems through common and different elements, and hence that the cell type influences the signalling pathways involved in the TRH-evoked responses.     

Immunohistochemistry of connexin 43 throughout anterior pituitary gland in a transgenic rat with green fluorescent protein-expressing folliculo-stellate cells

Folliculo-stellate (FS) cells in the anterior pituitary gland have been speculated to possess multifunctional properties. Because gap junctions (GJ) have been identified between FS cells, FS cells may be interconnected electrophysiologically by GJ and serve as signal transmission networks to modulate hormone release in the anterior pituitary gland. But whether GJ are localized among FS cells from the pars tuberalis through the pars distalis is unclear. The S100b-GFP transgenic rat has recently been generated, which expresses green fluorescent protein (GFP) specifically in FS cells in the anterior pituitary. This model is expected to be a powerful tool for studies of FS cells. The purpose of the present paper was therefore to examine the localization of GJ on connexin 43 immunohistochemistry throughout the anterior pituitary gland of S100b-GFP rats under confocal laser microscopy. The localization patterns of FS cells was also observed in primary culture of anteiror pituitary cells and the question of whether GJ between FS cells are reconstructed in vitro was investigated. In vivo studies showed that GJ were present specifically between FS cells from the pars tuberalis to the pars distalis in the anterior pituitary gland. The appearance of FS cells was distinguished into two types, with localization of GJ differing between types. In vitro, it was observed for the first time that FS cells in primary culture could be categorized into two types. In vivo localization of GJ between FS cells was reconstructed in vitro. These morphological observations are consistent with the hypothesis that FS cells form an electrophysiological network throughout the anterior pituitary for signal transmission.     

Regulation of estrogen receptor mRNA in normal and neoplastic rat pituitary tissues

The effects of estradiol 17β (E₂) on the regulation of estrogen receptor (ER) mRNA amounts in normal and neoplastic rat pituitary tissues were analyzed by in situ hybridization with an oligonucleotide probe. E₂ treatment produced a significant increase in ER mRNA amounts in two transplantable pituitary tumors (MtT/Wl5 and MtT/F4) and in the GH₃ cell line. ER mRNA amounts were also increased In normal pituitaries after 6 weeks of E₂ treatment, but the differences were not significant. Biochemical assay of ER proteins confirmed the presence of ER protein in MtT/Wl 5 and MtT/F4 tumors. “Cytoplasmic” ER proteins were decreased by E₂ in the MtT/Wl5 tumor.These results indicate that ER mRNA is present in normal pituitaries and in pituitary tumors and can be regulated by estrogen treatment in vivo and in vitro. The inhibitory effects of high estrogen concentration on proliferation of transplantable pituitary tumors in vivo and GH₃ cells in vitro is not explained by the absence of ER mRNAs in these tumors.     

Caffeine enhancement of electrical activity through direct blockade of inward rectifying K+ currents in GH3 rat anterior pituitary cells

Treatment of rat anterior pituitary GH₃ cells with caffeine causes a reversible enhancement of electrical activity superimposed over a depolarization of the plasma membrane potential. Similar results are obtained with theophylline, but not with isobutylmethylxanthine or forskolin. The effects of caffeine are not related to Ca²⁺ liberation from intracellular stores since they are not affected by incubation of the cells with ryanodine or thapsigargin. Furthermore, caffeine-induced hyperpolarization of the membrane is not detectable even in cells in which Ca²⁺ liberation from inositol 1,4,5-trisphosphate-sensitive compartments produces a prominent transient hyperpolarization in response to thyrotropin-releasing hormone. Reductions of Ca²⁺-dependent K⁺ currents caused by partial block of L-type Ca²⁺ channels by caffeine are not sufficient to explain the effects of the xanthine, since the results obtained with caffeine are not mimicked by direct blockade of Ca²⁺ channels with nisoldipine. GH₃ cell inwardly rectifying K⁺ currents are inhibited by caffeine. Studies on the voltage dependence of the caffeine-induced effects indicate a close correlation between alterations of electrical parameters and reported values of steady-state voltage dependence of inactivation of these currents. We conclude that, as previously shown for thyrotropin-releasing hormone, modulation of inwardly rectifying K⁺ currents plays a major role determining the firing rate of GH₃ cells and its enhancement by caffeine.     

Folliculostellate Cells Are Required for Laminin Release from Gonadotrophs in Rat Anterior Pituitary

The anterior pituitary gland is organized tissue comprising hormone-producing cells and folliculostellate (FS) cells. FS cells interconnect to form a meshwork, and their cytoplasmic processes are anchored by a basement membrane containing laminin. Recently, we developed a three-dimensional (3D) cell culture that reproduces this FS cell architecture. In this study of the novel function of FS cells, we used transgenic rats that express green fluorescent protein in FS cells for the 3D culture. Anterior pituitary cells were cultured with different proportions of FS cells (0%, 5%, 10%, and 20%). Anterior pituitary cells containing 5–20% FS cells formed round/oval cell aggregates, whereas amorphous cell aggregates were formed in the absence of FS cells. Interestingly, immunohistochemistry showed laminin-immunopositive cells instead of extracellular laminin deposition in FS cell-deficient cell aggregates. Double-immunostaining revealed that these laminin-immunopositive cells were gonadotrophs. Laminin mRNA expression did not differ in relation to the presence or absence of FS cells. When anterior pituitary cells with no FS cells were cultured with FS cell-conditioned medium, the proportion of laminin-immunopositive cells was lower than in control. These results suggest that a humoral factor from FS cells is required for laminin release from gonadotrophs.