Amphetamine antagonizes the presynaptic inhibitory effect of clonidine through an interaction at the level of the alpha 2-adrenoceptors

Acetazolamide increases locomotion, exploratory behavior, and weight loss following social stress: A treatment for emotional eating?

Sympathomimetics are effective, centrally acting drugs that induce weight loss through their potent anorexic and locomotor properties. We reported that sympathomimetics antagonize catecholamine-dependent, alpha-2 adrenergic receptor-dependent signal transduction mediated by chloride/bicarbonate transport. We posit that other drugs that target cellular chloride/bicarbonate antiport would similarly demonstrate anorectic properties, induce locomotion, and diminish weight gain. Male and female inbred mice were housed in groups or stressed by prolonged social isolation. Mice consumed either normal chow or a high fat, high fructose corn syrup, (i.e. "Western") diet. To inhibit chloride/bicarbonate transport, acetazolamide (ACT, 3 mM) was added to the drinking water. Rodents underwent evaluations of exploratory locomotion and learning with the object recognition test. Mice consuming a "Western" diet gain more weight compared to mice given a normal diet. When placed on a "Western" diet, stressed mice gained weight more rapidly than unstressed. The body weight of mice fed a normal diet with ACT was significantly reduced compared to control mice not given ACT (weight, g ± SEM), 23.7 ± 0.8 v. 21.0 ± 0.5, p = 0.02. ACT did not reduce weight gain in animals chronically maintained on a "Western" diet. Compared to unstressed mice, living in social isolation reduced spontaneous exploratory locomotion time, an indicator of anxiety, in male mice (sec +SEM) from 22.8 ± 3.5 to 12.2 ± 2.1 (p < 0.001), and in female mice, from 47 ± 5.7 to 19.6 ± 2.3 (p < 0.001). ACT had no effect on exploration time in unstressed mice, but ACT completely restored the diminished exploratory locomotion time found in stressed mice compared to unstressed mice. The ratio of time spent exploring new objects compared to familiar items (discrimination ratio [DR]) was reduced following social isolation in males from 2.6 ± 0.5 to 1.2 ± 0.2 (p < 0.05) and in females from 3.8 ± 0.6 to 1.5 ± 0.2 (p < 0.01). ACT normalized the DR ratio of the stressed mice. Decreased food consumption and greater locomotor activity induced by ACT may contribute to acute weight loss; this effect is diminished when rodents were maintained on an unhealthful Western diet. Inhibition of chloride/bicarbonate transport through agents such as acetazolamide could offer a safe, new approach to achieving weight loss.

Chromosomal instability in untreated primary prostate cancer as an indicator of metastatic potential

Background

Metastatic prostate cancer (PC) is highly lethal. The ability to identify primary tumors capable of dissemination is an unmet need in the quest to understand lethal biology and improve patient outcomes. Previous studies have linked chromosomal instability (CIN), which generates aneuploidy following chromosomal missegregation during mitosis, to PC progression. Evidence of CIN includes broad copy number alterations (CNAs) spanning > 300 base pairs of DNA, which may also be measured via RNA expression signatures associated with CNA frequency. Signatures of CIN in metastatic PC, however, have not been interrogated or well defined. We examined a published 70-gene CIN signature (CIN70) in untreated and castration-resistant prostate cancer (CRPC) cohorts from The Cancer Genome Atlas (TCGA) and previously published reports. We also performed transcriptome and CNA analysis in a unique cohort of untreated primary tumors collected from diagnostic prostate needle biopsies (PNBX) of localized (M0) and metastatic (M1) cases to determine if CIN was linked to clinical stage and outcome.

Methods

PNBX were collected from 99 patients treated in the VA Greater Los Angeles (GLA-VA) Healthcare System between 2000 and 2016. Total RNA was extracted from high-grade cancer areas in PNBX cores, followed by RNA sequencing and/or copy number analysis using OncoScan. Multivariate logistic regression analyses permitted calculation of odds ratios for CIN status (high versus low) in an expanded GLA-VA PNBX cohort (n = 121).

Results

The CIN70 signature was significantly enriched in primary tumors and CRPC metastases from M1 PC cases. An intersection of gene signatures comprised of differentially expressed genes (DEGs) generated through comparison of M1 versus M0 PNBX and primary CRPC tumors versus metastases revealed a 157-gene “metastasis” signature that was further distilled to 7-genes (PC-CIN) regulating centrosomes, chromosomal segregation, and mitotic spindle assembly. High PC-CIN scores correlated with CRPC, PC-death and all-cause mortality in the expanded GLA-VA PNBX cohort. Interestingly, approximately 1/3 of M1 PNBX cases exhibited low CIN, illuminating differential pathways of lethal PC progression.

Conclusions

Measuring CIN in PNBX by transcriptome profiling is feasible, and the PC-CIN signature may identify patients with a high risk of lethal progression at the time of diagnosis.

Effects of muscarinic toxins MT1 and MT2 from green mamba on different muscarinic cholinoceptors

MT1 and MT2, polypeptides from green mamba venom, known to bind to muscarinic cholinoceptors, behave like muscarinic agonists in an inhibitory avoidance task in rats. We have further characterised their functional effects using different preparations. MT1 and MT2 behaved like relatively selective muscarinic M1 receptor agonists in rabbit vas deferens, but their effects were not reversed by washing or prevented by muscarinic antagonists, although allosteric modulators altered responses to MT1. Radioligand binding experiments indicated that both toxins irreversibly inhibited [3H]N-methylscopolamine binding to cloned muscarinic M1 and M4 receptors, and reduced binding to M5 subtype with lower affinity, while they reversibly inhibited the binding of [3H]prazosin to rat cerebral cortex and vas deferens, with 20 fold lower affinity. High concentrations of MT1 reversibly blocked responses of vas deferens to noradrenaline. MT1 and MT2 appear to irreversibly activate muscarinic M1 receptors at a site distinct from the classical one, and to have affinity for some alpha-adrenoceptors.

I1-imidazoline receptors. Definition, characterization, distribution, and transmembrane signaling

Data were presented showing that I1-imidazoline sites show a unique ligand specificity that differs markedly from that of any of the alpha 2-adrenergic subtypes or the I2-imidazoline sites labeled by [3H]idazoxan. On the other hand, the ligand specificity of I1-imidazoline sites is maintained across mammalian species (cow, rat, dog, and human) and between different tissues and cell types. I1-Imidazoline sites can be further distinguished from I2 sites because the latter, unlike I1 sites, were not present in RVLM membranes from bovine brain stem. Furthermore, I1-imidazoline sites were modulated by guanine nucleotides with a specificity appropriate for a receptor coupled to G-protein and were mainly localized to plasma membranes. I1-Imidazoline sites show a unique pattern of distribution between diverse tissues and cell types and appear to be a neuroepithelial marker as well as being present in secretory cells of the pancreatic islets. The widespread distribution of I1-imidazoline sites implies that the functional significance of this putative receptor may have been underestimated. The signaling pathway associated with the I1-imidazoline receptor remains to be fully elucidated, but is likely that activation of phospholipase A2 leading to release of arachidonic acid and subsequent generation of prostaglandins plays a major role.

N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) impairs neurotransmission in the vas deferens of the rat

1. The in vitro effects of N-(2-chloroethyl)-N-ethyl-bromobenzylamine (DSP4) were studied in the rat vas deferens. 2. DSP4 inhibited the biphasic motor response induced by field stimulation in a concentration-dependent manner. The concentration of DSP4 that elicited 50% of the maximal inhibition of the twitch response induced by 3 Hz was 10 microM. 3. DSP4 10 microM abolished the motor response induced by exogenously applied noradrenaline and 0.1 mM ATP. Phentolamine (an alpha-adrenoceptor blocker) prevented DSP4 inhibitory effect. 4. DSP4 inhibitory effect was no due to the activation of alpha 2-presynaptic adrenoceptor mechanisms. 5. DSP4 impairs neurotransmission in the rat vas deferens by a postsynaptic alpha 1-adrenoceptor blockade and by an inhibition of the purinergic response.