Effects and metabolism of steroid hormones in human neuroblastoma cells

The development of the central nervous system is influenced by sex steroids and by their metabolites. However, little information on the possible effects of steroid hormones on neuroblastoma cells is available. Human neuroblastoma cell lines have been used as a model of human neuroblasts in vitro to study the metabolism of steroid hormones; in addition, the effects of steroids and steroid antagonists on neuroblastoma cell growth have also been investigated. The results obtained show that SH-SY5Y human neuroblastoma cells may actively metabolize testosterone and progesterone to their respective 5 alpha-reduced metabolites and that differentiation of neuroblastoma cells is paralleled by a significant increase in expression of the type-1 5 alpha-reductase and of the formation of steroid metabolites. All these data are suggestive of a potential role of steroid 5 alpha-reduced metabolites in the biology of neuroblastoma cells. Studies performed to analyze the role of steroid hormones on neuroblastoma cell proliferation show that progesterone at low doses may induce minor stimulation, and at higher doses, a toxic effect on the neuroblastoma cell line SK-N-SH is seen. Moreover, the antiprogestin 17 beta-hydroxy-11 beta-(4-dimethylamino-phenyl-1)-17-(prop-1-ynyl)estra-4,9-dien+ ++-3-one (RU486) decreases the proliferation of these cells in a dose-dependent manner. The effect of RU486 is not antagonized by either progesterone or dexamethasone, a result that seems to exclude the action of RU486 via classic intracellular steroid hormone receptors.

Effects of carbamazepine on plasma extravasation and bronchoconstriction induced by substance P, capsaicin, acetaldehyde and histamine in guinea-pig lower airways

We evaluated the in vivo effects of the pretreatment with carbamazepine (CBZ) at different doses (10, 20 and 40 mg/kg p.o.) on the Evans-blue extravasation and on bronchoconstriction induced by different substances in guinea-pig tracheal tissue. The drug dose-dependently inhibited the extravasation induced by substance P (SP), capsaicin and acetaldehyde, but not that induced by histamine. At the highest dose (40 mg/kg) CBZ inhibited the bronchoconstriction induced by SP, capsaicin and acetaldehyde, but not that produced by histamine administration. The in vitro study with guinea-pig tracheal preparation indicates that the drug does not interfere with the binding of SP to its receptors. Our results suggest that CBZ exerts a protective activity against the pro-inflammatory action of SP.

Sutureless scleral fixation of intraocular lenses

A technique is presented in which pars plana fixation of a posterior chamber intraocular lens (IOL) is achieved by the transscleral passage of the haptics. The IOL used has three equidistant supple loops, each attached to an armed suture, which serve as haptics. A specially designed needle driver is used to pass the sutures into and out of the eye through the pars plana and along the surface of the sclera, where they are severed by cautery. Stable fixation is achieved without contact with the inner tissues of the eye, and no additional sutures are necessary. Lens stability is maintained even in the presence of asymmetrical fibrosis of the capsular remnants.

Effects of epidermal growth factor on the [3H]-thymidine uptake in the SK-N-SH and SH-SY5Y human neuroblastoma cell lines

The studies on the factors that regulate the biology of the neuroblastoma cell lines may offer important information on the development of tissues and organs that derive from the neural crest. In the present paper we study the action of epidermal growth factor (EGF) on two human neuroblastoma cell lines: SK-N-SH which is composed at least of two cellular phenotypes (neuroblastic and melanocytic/glial cells), and its pure neuroblastic subclone SH-SY5Y. The results show that EGF (10 ng/ml) significantly stimulates the incorporation of [3H]-thymidine in the SK-N-SH cells only in the presence of fetal bovine serum (FBS) (control = 58,285 +/- 9327 cpm; EGF = 75,523 +/- 4457, p < 0.05). Such effect is not observed in the presence of a chemical defined medium, that is, in the absence of FBS (control = 100,997 +/- 4375; EGF = 95,268 +/- 4683; NS) In the SH-SY5Y cells the EGF does not modify the incorporation of [3H]-thymidine either in the presence of 10% of BFS (control = 113,838 +/- 6978; EGF = 119,434 +/- 9441; NS) or in its absence (control = 46,197 +/- 3335; EGF = 44,472 +/- 3493; NS). The results here reported suggest that: a) EGF may affect the proliferation of cells derived from a primary human neuroblastoma; b) this is evident by the EGF-induced increase of [3H]-thymidine incorporation in SK-N-SH cells; c) it is required the presence of other growth factors, present in the FBS, for the mitogenic action to be accomplished; d) since the pure neuroblastic SH-SY5Y cell line are refractory to the EGF, the effects observed in SK-N-SH cells probably occur on the melanocytic/glial cell subpopulation.

Alpha7 and alpha8 nicotinic receptor subtypes immunopurified from chick retina have different immunological, pharmacological and functional properties

Nicotinic receptors are present in the chick retina, but their structure and functional characteristics are still unclear. Using anti-alpha7 and anti-alpha8 subunit-specific antibodies, we immunopurified the alpha7 and alpha8 subtypes of chick retina neuronal nicotinic receptors. When analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, the two purified subtypes consistently showed a similar peptide composition characterized by the presence of two major peptides of M(r) 58 +/- 1 and 54 +/- 1 kDa, and two minor peptides of 67 and 61 +/- 1 kDa. In the alpha7 subtype, the 58 kDa peptide was recognized by anti-alpha7 but not by anti-alpha8 antibodies; in the alpha8 subtype, the 58 kDa peptide was recognized only by anti-alpha8 antibodies. The alpha7 subtype had a single class of [125I]alpha-bungarotoxin binding sites with a K(D) value of 1.2 nM, whereas the purified alpha8 subtype had two classes of binding sites, one with a K(D) of 5.5 nM and the other with very high affinity (KD 52 pM), but present in only 8% of the receptors. Competition binding experiments also showed the presence on the alpha8 subtype of high- and low-affinity classes of binding sites; the affinity for cholinergic drugs of the former was greater than that of the single class present on the alpha7 subtype. When reconstituted in planar lipid bilayers, both subtypes formed ligand-gated cation channels with major conductance levels of 42 and 52 pS but with different lifetimes; the two channels were activated by agonists and blocked by d-tubocurarine and the glycinergic antagonist strychnine. In line with the binding data, the reconstituted alpha8 subtype had greater agonist sensitivity than the alpha7 subtype.

Antiemetic efficacy of granisetron in patients with gynecological malignancies

The efficacy and tolerability of granisetron in the management of acute and delayed emesis was compared with that of a multiple antiemetic drug combination regimen, including metoclopramide, dexamethasone, lorazepam and orphenadrine. The trial was a randomized, cross-over study involving 111 patients with gynecological cancers undergoing chemotherapy with cisplatin. Granisetron was significantly more effective than the combination regimen during the first 24 h after chemotherapy; complete response, rates were 67 and 48%, respectively (p = 0.002). There was a significant reduction in the effectiveness of the combination during the second treatment cycle, compared with the first. In contrast, the efficacy of granisetron did not differ between the two cycles. The response rate during the 6 days after chemotherapy was 40.8% in both groups. At the end of the study, 55% of patients preferred granisetron and 23% preferred the combination (p < 0.001). Granisetron was well tolerated. The principal adverse event was headache, which was reported in 7% of patients. The results of this study confirm that granisetron is effective in the treatment of cisplatin-induced nausea and vomiting during the 24 h after chemotherapy.

Choriocarcinoma coexistent with intrauterine pregnancy: two additional cases and a review of the literature

Choriocarcinoma coexistent with normal intrauterine pregnancy is rare and poses questions about its origin. Although the development from trophoblastic remnants of previous pregnancies can not be excluded in some cases, the findings of incidental macro- and microscopic foci of choriocarcinoma in apparently normal placentas show the possible transformation of normal trophoblast into choriocarcinoma during an otherwise normal pregnancy. The diagnosis and management of choriocarcinoma coexistent with intrauterine pregnancy have changed dramatically over the decades but the survival rates are still unsatisfactory. In this review, we summarize some of the most common features of this disease.

RU 486 reduces morphine-induced analgesia in mice, but steroid receptors are not involved

The effects of subcutaneous pretreatment with the glucocorticoid/progesterone receptor antagonist RU 486 on the antinociceptive action of peripherally administered morphine were evaluated by the hot-plate test in mice. The steroid significantly reduced the analgesic effect of the opiate. Neither dexamethasone nor progesterone modified the effects of RU 486 on morphine-induced analgesia. Therefore, the present data indicate that the modulatory effect of RU 486 on morphine-induced analgesia does not involve the binding of this drug to classical steroid receptors.

Antiprogestins inhibit the binding of opioids to mu-opioid receptors in nervous membrane preparations

The present study showed that the glucocorticoid/progesterone antagonists, 17 beta-hydroxy-1 1 beta-(4-dimethylamino-phenyl-1)-17-(prop-1-ynyl)estra-4,9-dien+ ++-3-one (RU486) and 17 beta-hydroxy-11 beta-(4-dimethylamino-phenyl-1)-17-(propan-3-ol)estra-4,9-dien-3-o ne (ZK 98299), inhibit the binding of labeled dihydromorphine to mu-opioid receptors present on membrane preparations derived from rat and mouse brain, as well as from human neuroblastoma cells. The inhibitory effect of RU486 was dose-dependent and linked to a decrease of the affinity of labeled dihydromorphine to the mu-opioid receptors. Kinetic experiments have shown that RU486 induces a decrease of the association rate constant (k + 1) of dihydromorphine. RU486 also proved able to dissociate the dihydromorphine-mu-opioid receptor complex, although at a rate slower than that exhibited by unlabeled dihydromorphine. Finally, the addition of NaCl (100 mM) to the incubation buffer induced a 50% decrease of the inhibitory effect of RU486. A 6-day treatment of neuroblastoma cells with RU486 eliminated the inhibitory effect morphine exerts on the intracellular accumulation of cyclic AMP induced by prostaglandin E1. These results indicate that RU-486 may interact with brain mu-opioid receptors in vitro, by decreasing the affinity of opioid ligands.

Role of growth factors, steroid and peptide hormones in the regulation of human prostatic tumor growth

Previous work carried out in the authors' laboratory has shown that LHRH agonists directly inhibit the proliferation of hormone-responsive and hormone-independent human prostatic cancer cell lines (respectively LNCaP and DU145). In addition, the hormone-dependent LNCaP cells respond to a challenge with testosterone with an increase in growth rate. The following experiments have been performed to investigate whether the LHRH agonists might act by interfering with the stimulatory actions of either the EGF/TGF alpha system or androgens. The results obtained in LNCaP and DU145 cells show that LHRH agonists counteract the mitogenic action of the EGF/TGF alpha system. This effect is mediated by a decrease in the concentration of EGF receptors. In addition, in the hormone-dependent LNCaP cells, the treatment with LHRH agonists antagonizes the proliferation promoting effect of testosterone, which in turn appears to be mediated by the activation of the locally expressed EGF/TGF alpha system. Finally, the results suggest the presence in LNCaP cells of a soluble peptidase able to degrade LHRH. In conclusion, the present data suggest an intimate interplay among the actions of LHRH agonists, of androgens and of growth factors, thus, supporting the hypothesis that LHRH agonists may interfere with the EGF/TGF alpha stimulatory loop and with androgens in the control of the proliferation of human prostatic tumors.

Inhibition of luteinizing hormone-releasing hormone secretion by delta-opioid agonists in GT1-1 neuronal cells

The endogenous opioids play a major role in regulation of the secretion of hypothalamic LHRH. However, it is not clear whether opioids exert a direct effect on LHRH neurons or interfere with other neuronal systems impinging on the cells synthesizing LHRH. The neuronal LHRH-producing cell line GT1 provides a new model to evaluate which signals may directly modify LHRH release. In a previous paper it has been reported that opioid-binding sites of the delta-type are present in a clone of the GT1 cells (GT1-1). In the present study, the possible effects of opioids on the release of LHRH were studied in GT1-1 cells. The results obtained show that only the addition of opioid agonists that bind to delta-receptors brings about a significant inhibition of forskolin- or prostaglandin E2-stimulated LHRH release in GT1-1 cells. The effect of the delta-opioid agonist [D-Pen2,D-Pen5]enkephalin is dose dependent and is reversed by the universal opioid antagonist naltrexone and the delta-specific antagonist naltrindole. No effect of opioid agonists or antagonists was observed in unstimulated cells. These results suggest that opioids may control the release of LHRH also, acting directly on LHRH-producing neurons.

Effects of steroids on the brain opioid system

The experiments reported here add further evidence in support of the view that sex steroids may influence the binding characteristics of brain opioid receptors. In particular, it has been shown that: (a) the number of mu-opioid receptors varies in the hypothalamus of regularly cycling female rats according to the different phases of the estrous cycle, which are characterized by fluctuations of circulating levels of sex steroids; (b) the number of mu-opioid receptors decreases in the hypothalamus and in the corpus striatum when ovariectomized rats are submitted to treatments with estradiol and progesterone able to induce a "positive" feedback effect on LH release. A treatment with estrogen alone able to induce a "negative" feedback effect on LH release brings about an increase of the number of mu-opioid receptors in the thalamus and in the hippocampus; (c) in addition to the mu-receptors, receptors of the delta type may also be involved in the control of gonadotropin secretion; recent results here presented indicate that a line of immortalized hypothalamic cells (GT1 cells), which synthesize and secrete LHRH, present delta opioid receptors on their membranes; these are apparently involved in the control of LHRH release from these cells.

Human prostatic-carcinoma cell-line lncap degrades luteinizing-hormone-releasing hormone

Recent evidence suggests a direct antiproliferative effect of LHRH agonists on the prostatic carcinoma cell line LNCaP. In the present study the possible presence of a LHRH degrading activity (LHRH-DA) in soluble fractions of LNCaP cell homogenates has been investigated. The results obtained show that an LHRH-DA is present in the soluble fraction of LNCaP cells with apparent Km and Vmax values of 31.6 mu M and 4.5 pmol/min/mu g protein respectively. The degradation pattern of LHRH is characterized by two major initial degradation products identified as LHRH 1-5 and LHRH 1-6 fragments. The degradation of the tracer [pGlu-H-3]LHRH, used as a substrate, is inhibited by synthetic unlabelled LHRH (IC50 7.9 mu M) and by several LHRH agonists with different kinetics and potencies; the LHRH agonist [DSer-(tBu)(6),Gly(10)-Aza]LHRH was the most potent blocker of LHRH-DA present in LNCaP cells; this enzymatic activity is also inhibited in a dose dependent manner by somatostatin, TRH, bacitracin and dithiothreitol. The LHRH-DA present in the soluble fraction of LNCaP cells does not seem to be modified by the deprivation of steroids from the culture medium, In conclusion, the presence in LNCaP cells of a soluble peptidase able to degrade LHRH might reinforce the possibility that the prostate is a target for the action of LHRH and of LHRH analogs.

Characterization of functional opioid delta receptors in a luteinizing hormone-releasing hormone-producing neuronal cell line

Endogenous opioids participate in the regulation of gonadotropin secretion through an influence on the release of the hypothalamic LHRH. However, it is not clear whether opioids exert a direct effect on LHRH-producing neurons or interfere with other systems able to influence LHRH release. A neuronal LHRH-producing cell line (GT1) developed recently provides a good model to study the mechanisms controlling LHRH release. In the present study, the presence of opioid receptors on a subclone of GT1 cells (GT1-1) has been investigated. A specific and saturable binding of the 3H-labeled nonselective opioid ligand diprenorphine ([3H]DIP) was detected by a receptor binding assay on both intact GT1-1 cells and crude membrane preparations obtained from these cells. Analysis of saturation curves revealed that [3H]DIP apparently binds to a single class of sites with a Kd of 0.2 nM and a binding capacity of 125 fmol/mg protein, corresponding to approximately 20,000 sites/cell. Selective displacement of the binding of [3H]DIP to GT1-1 cells by [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin, [D-Pen2,D-Pen5]enkephalin (DPDPE), and U50488H, which are selective ligands, respectively, for mu-, delta-, and kappa-receptors, was also evaluated. Only the specific delta-ligand DPDPE produced a significant inhibition of the binding of [3H]DIP. [D-Ala2,N-Me-Phe4,Gly5-ol]Enkephalin and U50488H were totally ineffective. The inhibitory effect of the agonist DPDPE on the binding of [3H]DIP was decreased by the presence of sodium ions, a typical characteristic of the binding of agonists to opioid receptors. Finally, it has been observed that treatment with prostaglandins E1 and E2 produces a dramatic increase in cAMP accumulation in GT1-1 cells, and DPDPE is highly effective in suppressing this effect. On the basis of these results, it is possible to postulate the presence of functional delta-opioid receptors on GT1-1 cells. By extrapolation, one might suggest that endogenous opioids may affect LHRH neurons by two mechanisms: a direct one, acting via delta-receptors, and an indirect one, through the activation of neurons impinging on the LHRH system, which uses mu-receptors.

Steroid binding and metabolism in the luteinizing hormone-releasing hormone-producing neuronal cell line GT1-1

LHRH synthesis and release are modulated in vivo by gonadal steroids. Although immunocytochemical and autoradiographic studies failed to detect appreciable amounts of estrogen or androgen receptor in LHRH-producing neurons, the recent finding that the promoter region of the LHRH gene contains several steroid hormone-responsive elements indicates a possible direct effect of sex steroids on these specialized neurons. The immortalized LHRH-producing neuronal cell line, GT1, which became recently available, may allow the study of LHRH dynamics. The presence of specific binding sites for estrogen and androgens as well as the presence of the two major enzymatic pathways involved in modulation of androgen action (the 5 alpha-reductase/3 alpha-hydroxysteroid dehydrogenase and the aromatase) have been studied in the GT1-1 clone. High affinity, low capacity binding sites for [3H]estradiol (Kd, 0.11 nM; binding capacity, 6.2 fmol/mg protein) and for a ligand of the androgen receptor, [3H]R1881 (Kd, 0.054 nM; binding capacity, 9.58 fmol/mg protein), have been identified in this cell line. A 2-fold induction of androgen-binding sites has been observed after 3 days of treatment of GT1-1 cells with estradiol (1 microM), indicating that the estradiol binding is probably linked to a functional estrogen receptor. Aromatase and 5 alpha-reductase/3 alpha-hydroxysteroid dehydrogenase activities have been also tested in GT1-1 cells. Under the culture conditions adopted, no detectable aromatization of [1 beta 3H]delta 4-androstenedione to estrone was observed using the tritiated water method. On the other hand, GT1-1 cells efficiently converted testosterone into dihydrotestosterone and subsequently into 5 alpha-androstan-3 alpha,17 beta-diol. In conclusion, GT1-1 cells possess several elements of the machinery through which sex steroids may influence LHRH dynamics.

Effect of ovariectomy on the binding characteristics of hypothalamic mu opioid receptors in the rat

The present experiments have been performed to analyze whether ovariectomy, performed in adult female rats, might influence the binding characteristics of hypothalamic mu binding sites. To this purpose, different groups of ovariectomized females have been killed by decapitation 1, 3, 7, 15 and 21 days after surgery, and the binding characteristics (Bmax and Kd) of the mu receptors have been determined in their hypothalami. Dihydromorphine was used as a specific mu ligand. The data obtained have been compared with those derived from the hypothalami of adult female rats in the morning of proestrus, when the density of hypothalamic mu opioid receptors reaches its highest concentration. Blood from trunk vessels was also collected for the evaluation of serum LH levels by radioimmunoassay. The results obtained have shown that one day after ovariectomy, the number of hypothalamic mu opioid binding sites is as high as that found in proestrus animals. The number of these binding sites tends to decrease on days 3, 7 and 15 after surgery. On day 21 after gonadectomy, the number of mu binding sites results to be significantly lower than that observed in the hypothalami of intact female rats in the morning of proestrus and in the hypothalami of female animals castrated since one day. The value of the Kd did not show any variation on days 1, 3, 15 and 21; however, a significant increase of this parameter (which indicates a decrease of the affinity of the ligand for its receptors) was observed on day 7 after ovariectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

MacELLIPSE, a graphical aid to the problem of the joint confidence region: a practical example for ligand binding experiments

The analysis of receptor binding experiments involving saturation or displacement curves may represent a problem when data are obtained from a number of experimental groups characterized by different tissues or different treatments. The conceptual difficulty of comparing such binding parameters and the complexity in graphically representing many curves is often overcome using tables and statistical tests for uncorrelated parameters. These, however, might be misleading. In fact, computing parameters using a nonlinear least squares (NLLS) technique may yield a significant covariance or correlation in the parameter estimates. In the present paper we suggest a practical method for comparing curves from different experimental groups using the LIGAND program and present the program MacELLIPSE that permits the graphical representation of the binding results together with the correlation existing between the estimated parameters.

Androgen and progesterone metabolism in the central and peripheral nervous system

This paper summarizes the most recent data obtained in the authors' laboratory on the metabolism of testosterone and progesterone in neurons, in the glia, and in neuroblastoma cells. The activities of the 5 alpha-reductase (the enzyme that converts testosterone into dihydrotestosterone, DHT), and of the 3 alpha-hydroxysteroid dehydrogenase (the enzyme that converts DHT into 5 alpha-androstane-3 alpha, 17 beta-diol, 3 alpha-diol) have been first evaluated in primary cultures of neurons, oligodendrocytes and type-1 and -2 astrocytes, obtained from the fetal or neonatal rat brain. All the cultures were used on the fifth day. The formation of DHT of 3 alpha-diol was evaluated incubating the different cultures with labeled testosterone or DHT as substrates. The results obtained indicate that the formation of DHT takes place preferentially in neurons; however, type-2 astrocytes and oligodendrocytes also possess considerable 5 alpha-reductase activity, while type-1 astrocytes show a much lower enzymatic concentration. A completely different localization was observed for 3 alpha-hydroxysteroid dehydrogenase; the formation of 3 alpha-diol appears to be prevalently, if not exclusively, present in type-1 astrocytes; 3 alpha-diol is formed in very low yields by neurons, type-2 astrocytes and oligodendrocytes. The compartmentalization of two strictly correlated enzymes (5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase) in separate central nervous system (CNS) cell populations suggests the simultaneous participation of neurons and glial cells in the 5 alpha-reductive metabolism of testosterone. Subsequently it has been shown that, similarly to what happens when testosterone is used as the substrate, the 5 alpha-reductase which metabolizes progesterone into 5 alpha-pregnane-3,20-dione (DHP) shows a significantly higher activity in neurons than in glial cells; however, type-1 and -2 astrocytes as well as oligodendrocytes also possess some ability to 5 alpha-reduce progesterone. On the other hand, 3 alpha-hydroxysteroid dehydrogenase, the enzyme which converts DHP into 5 alpha-pregnane-3 alpha-ol-20-one, appears to be present mainly in type-1 astrocytes; much lower levels of this enzyme are present in neurons and in type-2 astrocytes. At variance with the previous results obtained using androgens as precursors, oligodendrocytes show considerable 3 alpha-hydroxysteroid dehydrogenase activity, even if this is statistically lower than that present in type-1 astrocytes. The existence of isoforms of the enzyme involved in androgen and progesterone metabolism is discussed.(ABSTRACT TRUNCATED AT 400 WORDS)