A novel role of the corticotrophin-releasing hormone regulating peptide, teneurin C-terminal associated peptide 1, on glucose uptake into the brain.

Teneurin C-terminal associated peptide (TCAP) is an ancient paracrine signalling agent that evolved via lateral gene transfer from prokaryotes into an early metazoan ancestor. Although it bears structural similarity to corticotrophin-releasing hormone (CRH), it inhibits the in vivo actions of CRH. The TCAPs are highly expressed in neurones, where they induce rapid cytoskeletal rearrangement and are neuroprotective. Because these processes are highly energy-dependent, this suggests that TCAP has the potential to regulate glucose uptake because glucose is the primary energy substrate in brain, and neurones require a steady supply to meet the high metabolic demands of neuronal communication. Therefore, the objective of the present study was to assess the effect of TCAP-mediated glucose uptake in the brain and in neuronal cell models. TCAP-mediated 18 F-deoxyglucose (FDG) uptake into brain tissue was assessed in male wild-type Wistar rats by functional positron emission tomography. TCAP-1 increased FDG uptake by over 40% into cortical regions of the brain, demonstrating that TCAP-1 can significantly enhance glucose supply. Importantly, a single nanomolar injection of TCAP-1 increased brain glucose after 3 days and decreased blood glucose after 1 week. This is corroborated by a decreased serum concentration of insulin and an increased serum concentration of glucagon. In immortalised hypothalamic neurones, TCAP-1 increased ATP production and enhanced glucose uptake by increasing glucose transporter recruitment to the plasma membrane likely via AKT and mitogen-activated protein kinase/ERK phosphorylation events. Taken together, these data demonstrate that TCAP-1 increases glucose metabolism in neurones, and may represent a peptide signalling agent that regulated glucose uptake before insulin and related peptides.

Development of a Rapid Fluorescence-Based High-Throughput Screening Assay to Identify Novel Kynurenine 3-Monooxygenase Inhibitor Scaffolds.

Kynurenine 3-monooxygenase (KMO) is a well-validated therapeutic target for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD) and Huntington's disease (HD). This work reports a facile fluorescence-based KMO assay optimized for high-throughput screening (HTS) that achieves a throughput approximately 20-fold higher than the fastest KMO assay currently reported. The screen was run with excellent performance (average Z' value of 0.80) from 110,000 compounds across 341 plates and exceeded all statistical parameters used to describe a robust HTS assay. A subset of molecules was selected for validation by ultra-high-performance liquid chromatography, resulting in the confirmation of a novel hit with an IC50 comparable to that of the well-described KMO inhibitor Ro-61-8048. A medicinal chemistry program is currently underway to further develop our novel KMO inhibitor scaffolds.

Teneurin-2 presence in rat and human odontoblasts.

Teneurins are transmembrane proteins consisting of four paralogues (Ten-1-4), notably expressed in the central nervous system during development. All teneurins contain a bioactive peptide in their carboxyl terminal named teneurin C-terminal associated peptide (TCAP). The present study analyzed the detailed distribution of teneurin-2-like immunoreactive (Ten-2-LI) cells in developing and mature rat molar teeth, as well as in mature human dental pulps. Ten-2 and TCAP-2 genic expressions were also evaluated in rat and human dental pulps. Finally, Ten-2-LI cells were analyzed during the repair process after dentin-pulp complex injury in rat lower molar teeth. For this, histological sections of rat molar teeth and human dental pulps were submitted to immunohistochemical techniques, while total RNA from developing rat teeth and mature human dental pulps were submitted to conventional RT-PCR. Ten-2-LI cells were evident in the initial bell stage of rat molar teeth development, especially in ectomesenchymal cells of the dental papilla. Ten-2-LI odontoblasts showed strong immunoreactivity in rat and human mature teeth. Ten-2 and TCAP-2 genic expressions were confirmed in rat and human dental pulps. Dentin-pulp complex injury resulted in a decrease of Ten-2-LI odontoblasts after traumatic injury. Interestingly, Ten-2-LI cells were also evident in the pulp cell-rich zone in all postoperative days. In conclusion, Ten-2-LI presence in rat and human odontoblasts was demonstrated for the first time and Ten-2/TCAP-2 genic expressions were confirmed in rat and human dental pulps. Furthermore, it was revealed that Ten-2-LI rat odontoblasts can be modulated during the regenerative process.

Chemical Biology Approaches for Characterization of Epigenetic Regulators.

Chemical biology approaches are a powerful means to functionally characterize epigenetic regulators such as histone modifying enzymes. We outline experimental protocols and best practices for the cellular characterization and use of "chemical probes" that selectively inhibit protein methyltransferases, many of which methylate histones to regulate heritable gene expression patterns. We describe biomarker assays to validate the probes in specific cellular systems, and provide guidelines for their use in functional characterization of methyltransferases including detailed protocols, examples, and controls. Together these techniques enable precision manipulation of cellular epigenomes and the exploration of the therapeutic potential of epigenetic targets in human disease.

Deferasirox (ICL670A) effectively inhibits oesophageal cancer growth in vitro and in vivo.

BACKGROUND AND PURPOSE: Growing evidence implicates iron in the aetiology of gastrointestinal cancer. Furthermore, studies demonstrate that iron chelators possess potent anti-tumour activity, although whether iron chelators show activity against oesophageal cancer is not known. EXPERIMENTAL APPROACH: The effect of the iron chelators, deferoxamine (DFO) and deferasirox, on cellular iron metabolism, viability and proliferation was assessed in two oesophageal adenocarcinoma cell lines, OE33 and OE19, and the squamous oesophageal cell line, OE21. A murine xenograft model was employed to assess the effect of deferasirox on oesophageal tumour burden. The ability of chelators to overcome chemoresistance and to enhance the efficacy of standard chemotherapeutic agents (cisplatin, fluorouracil and epirubicin) was also assessed. KEY RESULTS: Deferasirox and DFO effectively inhibited cellular iron acquisition and promoted intracellular iron mobilization. The resulting reduction in cellular iron levels was reflected by increased transferrin receptor 1 expression and reduced cellular viability and proliferation. Treating oesophageal tumour cell lines with an iron chelator in addition to a standard chemotherapeutic agent resulted in a reduction in cellular viability and proliferation compared with the chemotherapeutic agent alone. Both DFO and deferasirox were able to overcome cisplatin resistance. Furthermore, in human xenograft models, deferasirox was able to significantly suppress tumour growth, which was associated with decreased tumour iron levels. CONCLUSIONS AND IMPLICATIONS: The clinically established iron chelators, DFO and deferasirox, effectively deplete iron from oesophageal tumour cells, resulting in growth suppression. These data provide a platform for assessing the utility of these chelators in the treatment of oesophageal cancer patients.

C-Terminal region of teneurin-1 co-localizes with dystroglycan and modulates cytoskeletal organization through an extracellular signal-regulated kinase-dependent stathmin- and filamin A-mediated mechanism in hippocampal cells.

The pyramidal neurons in the hippocampus are extremely neuroplastic, and the complexity of dendritic branches can be dynamically altered in response to a variety of stimuli, including learning and stress. Recently, the teneurin family of proteins has emerged as an interneuronal and extracellular matrix signaling system that plays a significant role in brain development and neuronal communication. Encoded on the last exon of the teneurin genes is a new family of bioactive peptides termed the teneurin C-terminal-associated peptides (TCAPs). Previous studies indicate that TCAP-1 regulates axon fasciculation and dendritic morphology in the hippocampus. This study was aimed at understanding the molecular mechanisms by which TCAP-1 regulates these changes in the mouse hippocampus. Fluoresceinisothiocyanate (FITC)-labeled TCAP-1 binds to the pyramidal neurons of the CA2 and CA3, and dentate gyrus in the hippocampus of the mouse brain. Moreover, FITC-TCAP-1 co-localizes with ß-dystroglycan upon binding to the plasma membrane of cultured immortalized mouse E14 hippocampal cells. In culture, TCAP-1 stimulates ERK1/2-dependent phosphorylation of the cytoskeletal regulatory proteins, stathmin at serine-25 and filamin A at serine-2152. In addition, TCAP-1 induces actin polymerization, increases immunoreactivity of tubulin-based cytoskeletal elements and causes a corresponding increase in filopodia formation and mean filopodia length in cultured hippocampal cells. We postulate that the TCAP-1 region of teneurin-1 has a direct action on the cytoskeletal reorganization that precedes neurite and process development in hippocampal neurons. Our data provides novel evidence that functionally links the teneurin and dystroglycan systems and provides new insight into the molecular mechanisms by which TCAP-1 regulates cytoskeletal dynamics in hippocampal neurons. The TCAP-dystroglycan system may represent a novel mechanism associated with the regulation of hippocampal-function.

Iron Chelators: Development of Novel Compounds with High and Selective Anti-Tumour Activity.

Targeting essential nutrients (eg., those required for DNA synthesis) to inhibit cancer cell growth is a well established therapeutic strategy. A good example is the highly successful folate antagonist, methotrexate. However, up until recently, strategies to target iron which is also crucial for DNA synthesis have not been systematically explored to develop agents for the treatment of cancer. Over the last 15 years, our laboratory has embarked upon structure-activity studies designed to develop novel Fe chelators with anti-cancer efficacy. These studies have led to the development of the dipyridyl thiosemicarbazone chelators that show potent and selective anti-cancer activity and which overcome resistance to other cytotoxic agents. This class of compounds include the chelator, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), which at optimal doses markedly inhibits tumour growth and is well tolerated. Moreover, this ligand does not induce overt Fe-depletion in vivo, probably because very low doses (0.4 mg/kg) are effective at inhibiting tumour growth. Importantly, our compounds are far more active and less toxic than the chelator, Triapine®, that is being assessed in a wide variety of international clinical trials. A vital part of the mechanism of action of these compounds is their ability to form a redox-active Fe complex that generates radicals to inhibit tumour growth. Due to their relatively high lipophilicity and low molecular weight of this class of compounds, oral activity may be expected in addition to their well known efficacy via the intravenous route.

ATP7A is a novel target of retinoic acid receptor beta2 in neuroblastoma cells.

Increased retinoic acid receptor beta (RARbeta(2)) gene expression is a hallmark of cancer cell responsiveness to retinoid anticancer effects. Moreover, low basal or induced RARbeta(2) expression is a common feature of many human cancers, suggesting that RARbeta(2) may act as a tumour suppressor gene in the absence of supplemented retinoid. We have previously shown that low RARbeta(2) expression is a feature of advanced neuroblastoma. Here, we demonstrate that the ABC domain of the RARbeta(2) protein alone was sufficient for the growth inhibitory effects of RARbeta(2) on neuroblastoma cells. ATP7A, the copper efflux pump, is a retinoid-responsive gene, was upregulated by ectopic overexpression of RARbeta(2). The ectopic overexpression of the RARbeta(2) ABC domain was sufficient to induce ATP7A expression, whereas, RARbeta(2) siRNA blocked the induction of ATP7A expression in retinoid-treated neuroblastoma cells. Forced downregulation of ATP7A reduced copper efflux and increased viability of retinoid-treated neuroblastoma cells. Copper supplementation enhanced cell growth and reduced retinoid-responsiveness, whereas copper chelation reduced the viability and proliferative capacity. Taken together, our data demonstrates ATP7A expression is regulated by retinoic acid receptor beta and it has effects on intracellular copper levels, revealing a link between the anticancer action of retinoids and copper metabolism.

Cancer cell iron metabolism and the development of potent iron chelators as anti-tumour agents.

Cancer contributes to 50% of deaths worldwide and new anti-tumour therapeutics with novel mechanisms of actions are essential to develop. Metabolic inhibitors represent an important class of anti-tumour agents and for many years, agents targeting the nutrient folate were developed for the treatment of cancer. This is because of the critical need of this factor for DNA synthesis. Similarly to folate, Fe is an essential cellular nutrient that is critical for DNA synthesis. However, in contrast to folate, there has been limited effort applied to specifically design and develop Fe chelators for the treatment of cancer. Recently, investigations have led to the generation of novel di-2-pyridylketone thiosemicarbazone (DpT) and 2-benzoylpyridine thiosemicarbazone (BpT) group of ligands that demonstrate marked and selective anti-tumour activity in vitro and also in vivo against a wide spectrum of tumours. Indeed, administration of these compounds to mice did not induce whole body Fe-depletion or disturbances in haematological or biochemical indices due to the very low doses required. The mechanism of action of these ligands includes alterations in expression of molecules involved in cell cycle control and metastasis suppression, as well as the generation of redox-active Fe complexes. This review examines the alterations in Fe metabolism in tumour cells and the systematic development of novel aroylhydrazone and thiosemicarbazone Fe chelators for cancer treatment.

Regulation of neurite growth in immortalized mouse hypothalamic neurons and rat hippocampal primary cultures by teneurin C-terminal-associated peptide-1.

Teneurins are a highly conserved family of four type II transmembrane proteins that are expressed in the CNS. The protein possesses several functional domains including a unique bioactive 40-41 amino acid sequence at the extracellular terminus. Synthetic versions of this teneurin C-terminal-associated peptide (TCAP) can modulate cyclic AMP accumulation, cell proliferation and teneurin mRNA levels in vitro. Furthermore, i.c.v. injections of TCAP-1 into rat brain induce major changes in acoustic startle response behavior 3 weeks after administration, suggesting that the peptide may act to alter interneuron communication via changes in neurite and axon outgrowth. Synthetic mouse/rat TCAP-1 was used to treat cultured immortalized mouse hypothalamic cells, to determine if TCAP-1 could directly regulate neurite and axon growth. TCAP-1-treated cells showed a significant increase in the length of neurites accompanied by a marked increase in beta-tubulin transcription and translation as determined by real-time PCR and Western blot analysis, respectively. Changes in alpha-actinin-4 transcription and beta-actin protein expression were also noted. Immunofluorescence confocal microscopy using beta-tubulin antiserum showed enhanced resolution of beta-tubulin cytoskeletal elements throughout the cell. In order to determine if the effects of TCAP-1 could be reproduced in primary neuronal cultures, primary cultures of E18 rat hippocampal cells were treated with 100 nM TCAP-1. The TCAP-1-treated hippocampal cultures showed a significant increase in both the number of cells, dendritic branching and the presence of large and fasciculated beta-tubulin immunoreactive axons. These data suggest that TCAP acts, in part, as a functional region of the teneurins to regulate neurite and axonal growth of neurons.

Male and female prolactin receptor mRNA expression in the brain of a biparental and a uniparental hamster, phodopus, before and after the birth of a litter.

Prolactin receptor (PRL-R) mRNA transcript level was quantified in the choroid plexus (ChP) of a naturally biparental hamster, Phodopus campbelli, and its otherwise similar, yet nonpaternal, sibling species, Phodopus sungorus. Pair-housed males and females on the day before the birth of their first litter (G17), the day after birth (L1), lactation day 5 (L5), and unpaired animals that were sexually naïve, were tested. PRL-R mRNA transcript level relative to total RNA, was evaluated by reverse transcriptase-polymerase chain reaction using primers common to the long- and short-form of the PRL-R in Phodopus. In the ChP, a region implicated in prolactin transport into the central nervous system, females had the expected increase in PRL-R mRNA transcript from dioestrus to L5, consistent with known actions of prolactin. As predicted, males and females of the biparental species were similar, although PRL-R mRNA in naive males was higher than in dioestrus females. Males of the two species also differed as predicted. PRL-R mRNA transcript levels were higher in the biparental males. In addition, P. campbelli males had low PRL-R mRNA at G17 compared to L5. By contrast, non-paternal P. sungorus males had elevated PRL-R mRNA transcript levels on G17 relative to unpaired males. We conclude that PRL-R mRNA in the ChP is differentially regulated before and after birth in a paternal and a nonpaternal male.

Iron chelators as anti-neoplastic agents: current developments and promise of the PIH class of chelators.

The chelator currently used to treat iron (Fe) overload disease, desferrioxamine (DFO), has shown anti-proliferative activity against leukemia and neuroblastoma cells in vitro, in vivo and in clinical trials. Collectively, these studies suggest that Fe-deprivation may be a useful anti-cancer strategy. However, the efficacy of DFO is severely limited due to its poor ability to permeate cell membranes and bind intracellular Fe pools. These limitations have encouraged the development of other Fe chelators that are far more effective than DFO. One group of ligands that have been extensively investigated are those of the pyridoxal isonicotinoyl hydrazone (PIH) class. In this review the marked anti-proliferative effects of the PIH analogs are discussed with reference to their mechanisms of action and structure-activity relationships. In particular, we discuss the activity of a novel group of ligands that are "hybrid" chelators derived from our most effective PIH analogs and thiosemicarbazones. The anti-tumor activity of the PIH analogs and other chelators such as tachpyridine, O-trensox and the desferrithiocin analogs have been well characterized in vitro. However, further studies in animals are critical to evaluate their selective anti-tumor activity and potential as therapeutic agents.

An artificial peptide with corticotropin-releasing factor receptor-2 (CRF-R2) selective properties: the role of primary structure in the induction of signal transduction pathways.

Considerable plasticity can occur within the amino acid sequence of amphiphilic peptide hormones. This is particularly evident within the corticotropin-releasing factor (CRF) family of peptides where, despite less than 15% sequence similarity among the four paralogous lineages, all are capable of acting as high affinity ligands to members of the CRF receptor family. This suggests that these peptides could undergo many mutational changes and remain as high affinity ligands to their receptors as long as the functional motifs do not change radically. Because paralogous peptide lineages are a product of genome duplications, additional genes encoding peptide-like sequences, which through mutation have lost their functional integrity, may exist. Function to these sequences may be restored if the appropriate motifs are reinserted into the primary structure. We screened rat genomic DNA with highly degenerate polymerase chain reaction (PCR) primers targeted to hybridize with the termini of CRF-related sequences. One set of sauvagine-based primers hybridized with a 120-bp sequence. The theoretical peptide sequence (SV4) showed similarity to the CRF family of peptides at the primary structure level. The encoded sequence was prepared by solid-phase synthesis and its activity assayed against mouse R1 and human R1/R2 receptors. SV4 did not bind to either mouse or human variants of the R1 receptor, but did bind to the R2 receptor with an affinity comparable to human CRF. SV4 exhibited a similar efficacy of cellular activation as CRF in trials quantifying the acidification rate of human R2alpha-transfected Chinese hamster ovary (CHO) cells, but not R1-transfected cells. SV4 utilizes adenylate cyclase as the principal secondary messenger of R2 signal transduction but, unlike urocortin or sauvagine, does not activate guanylate cyclase-, calcium- or mitogen-activated protein (MAP) kinase-mediated pathways. These data suggest that this artificial peptide may be useful to understand the cyclic adenosine monophosphate (cAMP)-dependent component of the CRF-R2 signal transduction cascade, and that additional sequences in the genome may be used to engineer bioactive peptides.

Expression of prolactin receptors and regulation of cell proliferation by prolactin, corticotropin-releasing factor, and corticosterone in a neuroblastoma cell line.

The aetiology of neuroblastoma remains obscure, although a number of neuropeptides have been implicated in its pathogenesis. Using the mouse neuroblastoma cell line Neuro2a as a model, we have investigated the mitogenic actions of prolactin (PRL) and two hypothalamo-pituitary-adrenal stress axis hormones, corticotropin-releasing factor (CRF) and corticosterone. Using established polyclonal PRL receptor antisera with immunofluorescence cytochemistry, we show that the Neuro2a cells possess immunoreactive forms of both the long and short forms of the receptor. PRL and CRF were effective as mitogens in Neuro2a cell cultures, where a 10(-7) M concentration of PRL or CRF elicited a two-fold increase in the numbers of cells after 72 h (p < 0.0001). Corticosterone, however, attenuated their proliferation. These data suggest that prolactin may act to increase the proliferation and regulation of neuroblastomas and that the effects of PRL may be modified by hypothalamo-pituitary-adrenal hormones.

The effects of exercise on mood changes: the moderating effect of depressed mood.

BACKGROUND: The present study examined the extent to which pre-exercise depressed mood moderated the influence of exercise on changes in other mood dimensions. The study was conducted in an ecologically valid setting using participants with previous experience of aerobic dance exercise. We hypothesized that (a) exercise will be associated with improved mood regardless of depressed mood, (b) the effect of exercise on mood changes would be significantly greater among individuals that reported symptoms of depressed mood before exercise, and (c) that pre-exercise depressed mood will be associated with a mood profile comprising high anger, confusion, fatigue, and tension, with low vigor. METHODS: Participants were 80 (M=27.90 years, SD=4.32 years) exercisers who had attended an exercise class on a regular basis for the previous three months. Participants completed the Profile of Mood States-A 15 minutes before exercise and then immediately after an aerobic dance exercise class. To examine the proposed moderating influence of depressed mood, participants were grouped into either a no-depression group, or a depressed mood group using pre-exercise depression scores. The exercise intervention was an aerobic dance session where participants followed the moves of the instructor. The session lasted for 60 minutes including a warm-up, main session, and cool-down. RESULTS: Repeated measures MANOVA (time x depression/no-depression group) results indicated that anger, confusion, fatigue, tension, and vigor reduced significantly. Thus supporting the notion that exercise reduces negative mood. Results indicated that the reduction in anger, confusion, fatigue, and tension, and increase in vigor was significantly greater in the depressed mood group, hence consistent with theoretical predictions. Results demonstrated that pre-exercise depressed mood was associated with a negative mood profile as hypothesized. CONCLUSIONS: Findings lend support to the notion that exercise is associated with improved mood. However, findings show that this effect was significantly greater among individuals reporting symptoms of depressed mood before exercise.

Structure and biological activity of gonadotropin-releasing hormone isoforms isolated from rat and hamster brains.

Rat and hamster brain tissues were used to investigate the possible existence of a follicle stimulating hormone (FSH)-releasing factor with similar characteristics to the lamprey gonadotropin-releasing hormone III (lGnRH-III) form proposed in previous reports. The present studies involved isolation and purification of the molecule by high-performance liquid chromatography (HPLC), identification by radioimmunoassay, sequence analysis by automated Edman degradation, mass spectrometry and examination of biological activity. Hypothalamic extracts from both species contained an HPLC fraction that was immunoreactive to GnRH and coeluted with lGnRH-III and 9-hydroxyproline mGnRH ([Hyp(9)]GnRH). Determination of primary structure from purified total brain material demonstrated that the isolated molecule was [Hyp(9)]GnRH. This is the first report showing the presence of the posttranslationally modified form already known as [Hyp(9)]GnRH by primary sequence analysis. The biological activity of distinct GnRH peptides was also tested in vitro for gonadotropin release using rat pituitary primary cell cultures. The results showed that [Hyp(9)]GnRH stimulated both luteinizing hormone and FSH release, as already reported, whereas lGnRH-III had no action on the secretion of either gonadotropin.

Longevity and heavy metal resistance in daf-2 and age-1 long-lived mutants of Caenorhabditis elegans.

In the nematode Caenorhabditis elegans, dauer formation, stress resistance, and longevity are determined in part by DAF-2 (insulin receptor-like protein), AGE-1 (phosphatidylinositol-3-OH kinase catalytic subunit), and DAF-16 (forkhead transcription factor). Mutations in daf-2 and age-1 result in increased resistance to heat, oxidants, and UV. We have discovered that daf-2 and age-1 mutations result in increased Cd and Cu ion resistance in a 24 h toxicity assay. Lethal concentration (LC50) values for Cd and Cu ions in daf-2 and age-1 mutants were significantly (P<0.001) higher than in wild-type nematodes. However, LC50 values in daf-16;age-1 mutants were not significantly different, implying that metal resistance is influenced by a DAF-16-related function. As metallothionein (MT) proteins play a major role in metal detoxification, we examined the expression of MT genes both under noninducing conditions and after exposure to sublethal and acute heavy metal stress. MT1 mRNA levels were significantly (P<0.05) higher in daf-2 mutants compared to age-1 mutants and wild-type C. elegans under basal conditions. After 10 mM Cd treatment, induction of MT1 and MT2 mRNA was three- and twofold higher, respectively, in daf-2 mutant worms than in wild-type. However, a sublethal concentration of Cd (0.1 mM) resulted in even higher (three- to sevenfold) levels of both MT mRNAs in all strains. Cu did not induce MT1 or MT2 mRNAs. These results are consistent with a model in which the insulin-signaling pathway determines life span through regulation of stress protein genes

Complexes of gallium(III) and other metal ions and their potential in the treatment of neoplasia.

The metal complexes of a variety of ligands show diverse pharmacological properties. The potential of these compounds as antineoplastic agents is underlined by the success of the clinically used platinum complex cisplatin (cis-[(NH(3))(2)PtCl(2)]). In the current review, specific examples of gallium, copper, ruthenium and titanium complexes are discussed with special relevance to their use in the treatment of cancer. Some of these complexes have demonstrated marked activity in a number of animal models and for some compounds, clinical trials are anticipated or have already begun. Collectively, the results in the literature indicate that the study of metal complexes as antineoplastic agents deserves continued intensive investigation.

Molecular integration of hypothalamo-pituitary-adrenal axis-related neurohormones on the GnRH neuron.

Gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus is pivotal to the regulation of reproductive physiology in vertebrates. GnRH and the reproductive axis, in general, can be inhibited during periods of stress or injury. Stress, in the form of mechanical, psychological or immunological insult to an organism results in the activation of the hypothalamo-pituitary-adrenal (HPA) axis initiated by the hypothalamic release of corticotropin-releasing factor (CRF). Recent studies indicate that CRF may act either directly on the GnRH neuron to down-regulate GnRH synthesis, or indirectly via a beta-endorphin-mediated pathway. Moreover, in vitro studies suggest that CRF-related peptides can increase the sensitivity of the GnRH neuron to prolactin by increasing the synthesis of the prolactin receptor.