Betty Exintaris

Novel drug targets for the pharmacotherapy of benign prostatic hyperplasia (BPH)

Benign prostatic hyperplasia (BPH) is the major cause of lower urinary tract symptoms in men aged 50 or older. Symptoms are not normally life threatening, but often drastically affect the quality of life. The number of men seeking treatment for BPH is expected to grow in the next few years as a result of the ageing male population. Estimates of annual pharmaceutical sales of BPH therapies range from

Male contraception via simultaneous knockout of α1A-adrenoceptors and P2X1-purinoceptors in mice

US 3 to 10 billion, yet this market is dominated by two drug classes. Current drugs are only effective in treating mild to moderate symptoms, yet despite this, no emerging contenders appear to be on the horizon. This is remarkable given the increasing number of patients with severe symptoms who are required to undergo invasive and unpleasant surgery. This review provides a brief background on prostate function and the pathophysiology of BPH, followed by a brief description of BPH epidemiology, the burden it places on society, and the current surgical and pharmaceutical therapies. The recent literature on emerging contenders to current therapies and novel drug targets is then reviewed, focusing on drug targets which are able to relax prostatic smooth muscle in a similar way to the α1‐adrenoceptor antagonists, as this appears to be the most effective mechanism of action. Other mechanisms which may be of benefit are also discussed. It is concluded that recent basic research has revealed a number of novel drug targets such as muscarinic receptor or P2X‐purinoceptor antagonists, which have the potential to produce more effective and safer drug treatments.

Inositol trisphosphate‐dependent Ca2+ stores and mitochondria modulate slow wave activity arising from the smooth muscle cells of the guinea pig prostate gland

Significance The search for a viable male contraceptive target has been a medical challenge for many years. Most strategies have focused on hormonal or germ-line strategies to produce dysfunctional sperm that are incapable of fertilization. The problem with such approaches is that they have intolerable side effects such as affecting male sexual activity or causing long-term irreversible effects on fertility. In addition, some strategies may transmit detrimental changes to future offspring. This manuscript describes a male contraceptive target within the autonomic nervous system, which would not affect the long-term viability of sperm nor the sexual or general health of males. In addition, due to the nature of the target, the contraceptive has the potential to be orally administered. Therapeutic targets for male contraception are associated with numerous problems due to their focus on disrupting spermatogenesis or hormonal mechanisms to produce dysfunctional sperm. Here we describe the dual genetic deletion of α1A-adrenergic G protein-coupled receptors (adrenoceptors) and P2X1-purinoceptor ligand gated ion channels in male mice, thereby blocking sympathetically mediated sperm transport through the vas deferens during the emission phase of ejaculation. This modification produced 100% infertility without effects on sexual behavior or function. Sperm taken from the cauda epididymides of double knockout mice were microscopically normal and motile. Furthermore, double knockout sperm were capable of producing normal offspring following intracytoplasmic sperm injection into wild-type ova and implantation of the fertilized eggs into foster mothers. Blood pressure and baroreflex function was reduced in double knockout mice, but no more than single knockout of α1A-adrenoceptors alone. These results suggest that this autonomic method of male contraception appears free of major physiological and behavioral side effects. In addition, they provide conclusive proof of concept that pharmacological antagonism of the P2X1-purinoceptor and α1A-adrenoceptor provides a safe and effective therapeutic target for a nonhormonal, readily reversible male contraceptive.

Spontaneous Ca2+ Signaling of Interstitial Cells in the Guinea Pig Prostate

Background and purpose:  Changes in smooth muscle tone of the prostate gland are involved in aetiology of symptomatic prostatic hyperplasia, however the control mechanisms of prostatic smooth muscle are not well understood. Here, we have examined the role of internal Ca2+ compartments in regulating slow wave activity in the guinea pig prostate.

Adopting an active learning approach to teaching in a research-intensive higher education context transformed staff teaching attitudes and behaviours

PURPOSE We investigated whether prostate interstitial cells generate spontaneous Ca(2+) oscillation, a proposed mechanism underlying pacemaker potentials to drive spontaneous activity in stromal smooth muscle cells. MATERIALS AND METHODS Intracellular free Ca(2+) in portions of guinea pig prostate and freshly isolated, single prostate interstitial cells were visualized using fluo-4 Ca(2+) fluorescence. Spontaneous electrical activity was recorded in situ with intracellular microelectrodes. RESULTS In whole tissue preparations spontaneous Ca(2+) flashes firing synchronously across all smooth muscle cells within the field of view resulted in muscle wall contractions. Nonpropagating Ca(2+) waves were also recorded in individual smooth muscle cells. Nifedipine (Sigma®) (1 μM) largely decreased or abolished these Ca(2+) flashes and suppressed slow wave discharge upon blockade of their superimposed action potentials. Isolated prostate interstitial cells were readily distinguished from smooth muscle cells by their spiky processes and lack of contraction during intracellular Ca(2+) increases. Prostate interstitial cells generated spontaneous Ca(2+) transients in the form of whole cell flashes, intracellular Ca(2+) waves or localized Ca(2+) sparks. All 3 Ca(2+) signals were abolished by nicardipine (1 μM), cyclopiazonic acid (10 μM), caffeine (Sigma) (10 mM) or extracellular Ca(2+) removal. CONCLUSIONS Prostate interstitial cells generate spontaneous Ca(2+) transients that occur at a frequency comparable to Ca(2+) flashes in situ or slow waves relying on functional internal Ca(2+) stores. However, unlike other interstitial cells in the urinary tract, Ca(2+) influx through L-type Ca(2+) channels is fundamental to Ca(2+) transient firings in prostate interstitial cells. Thus, it is not possible to conclude that prostate interstitial cells are responsible for pacemaker potential generation.

Role of connexin 43 in the maintenance of spontaneous activity in the guinea pig prostate gland

ABSTRACT The conventional lecture has significant limitations in the higher education context, often leading to a passive learning experience for students. This paper reports a process of transforming teaching and learning with active learning strategies in a research-intensive educational context across a faculty of 45 academic staff and more than 1000 students. A phased approach was used, involving nine staff in a pilot phase during which a common vision and principles were developed. In short, our approach was to mandate a move away from didactic lectures to classes that involved students interacting with content, with each other and with instructors in order to attain domain-specific learning outcomes and generic skills. After refinement, an implementation phase commenced within all first-year subjects, involving 12 staff including three from the pilot group. The staff use of active learning methods in classes increased by sixfold and sevenfold in the pilot and implementation phases, respectively. An analysis of implementation phase exam questions indicated that staff increased their use of questions addressing higher order cognitive skills by 51%. Results of a staff survey indicated that this change in practice was caused by the involvement of staff in the active learning approach. Fifty-six percent of staff respondents indicated that they had maintained constructive alignment as they introduced active learning. After the pilot, only three out of nine staff agreed that they understood what makes for an effective active learning exercise. This rose to seven out of nine staff at the completion of the implementation phase. The development of a common approach with explicit vision and principles and the evaluation and refinement of active learning were effective elements of our transformational change management strategy. Future efforts will focus on ensuring that all staff have the time, skills and pedagogical understanding required to embed constructively aligned active learning within the approach.

Nitric Oxide Signaling Pathways Involved in the Inhibition of Spontaneous Activity in the Guinea Pig Prostate

BACKGROUND AND PURPOSE To investigate the role of connexin 43 in the maintenance of spontaneous activity in prostate tissue from young and old guinea pigs.

Heterogeneity Amongst 5-HT3 Receptor Subunits: Is this Significant?

PURPOSE We investigated nitric oxide mediated inhibition of spontaneous activity recorded in young and aging guinea pig prostates. MATERIALS AND METHODS Conventional intracellular microelectrode and tension recording techniques were used. RESULTS The nitric oxide donor sodium nitroprusside (10 μM) abolished spontaneous contractions and slow wave activity in 5 young and 5 aging prostates. Upon adding the nitric oxide synthase inhibitor L-NAME (10 μM) the frequency of spontaneous contractile and electrical activity was significantly increased in each age group. This increase was significantly larger in 4 to 8 preparations of younger vs aging prostates (about 40% to 50% vs about 10% to 20%, 2-way ANOVA p<0.01). Other measured parameters, including the duration, amplitude and membrane potential of spontaneous electrical and contractile activity, were not altered from control values. The guanylate cyclase inhibitor ODQ (10 μM) significantly increased the frequency of spontaneous activity by 10% to 30% in 6 young guinea pig prostates (Student paired t test p<0.05). However, it had no effect on aging prostates. The cGMP analogue 8-Br-GMP (1 μM) and the PDE5 inhibitor dipyridamole (1 μM) significantly decreased the frequency of contractile activity by about 70% in 4 to 9 young and older prostates (Student paired t test p<0.05). CONCLUSIONS The decrease in the response to L-NAME in spontaneous contractile and slow wave activity in aging prostate tissue compared to that in young prostates suggests that with age there is a decrease in nitric oxide production. This may further explain the increase in prostatic smooth muscle tone observed in age related prostate specific conditions, such as benign prostatic hyperplasia.

Functional characterisation of hemokinin-1 in mouse uterus

The serotonin 3 (5-HT₃) receptor is a ligand gated ion channel unlike the other 5-HT receptors which are G protein coupled receptors. The functional 5-HT₃ receptor forms a pentamer of five symmetrically arranged subunits surrounding a central pore. The 5-HT(3A) subunit was first identified at a molecular level and can form functional homomers or heteromers with the 5-HT(3B) subunit. Recently, three new 5-HT₃ subunits have been discovered and these can also form functional heteromers with the 5-HT(3A) subunit. In addition, splice variants of the 5-HT₃ subunits have also been reported. These findings have markedly increased the complexity of the 5-HT₃ receptor and may form part of the explanation of unresolved differences between studies investigating 5-HT₃ receptor function in cell lines compared with native tissues. In this review we discuss the properties of the different subunits and their distribution to determine if they contribute to functional changes in the 5-HT₃ receptor. Several recent pharmacogenomic studies have revealed single nucleotide polymorphisms (SNPs) and other variations in the different 5-HT₃ receptor subunits that are associated with various clinical conditions. We discuss the implications of these findings with respect to drug design and tailored pharmacogenomic therapies.

Tamsulosin modulates, but does not abolish the spontaneous activity in the guinea pig prostate gland

The preprotachykinin gene Tac4 expressed in murine uterus and placenta is thought to encode a peptide RSRTRQFYGLM-NH(2), mouse hemokinin 1. We have examined the uterotonic effects of mouse hemokinin 1 and its N-terminally truncated analogue, mouse hemokinin 1(2-11) on mouse uterus. Mouse hemokinin 1(2-11) was equieffective with but slightly less potent than substance P in tissues from non-pregnant Swiss mice. On myometrium from Balb C mice primed with oestrogen the positions of concentration-response curves to substance P and the mouse hemokinins were similar to those of neurokinin A, but the maximum responses were lower. The tachykinin NK(1) receptor antagonist, 1-{2-(3, 4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl) piperidin-3-yl]ethyl}-4phenyl-1-azonia-bicyclo[2.2.2]octane (SR 140333), reduced the effects of the agonists in tissues from both groups of mice. In myometria from late pregnant (Days 17-18) Balb C mice the responses to mouse hemokinin 1(2-11) were less potent than in those from oestrogen-primed mice. Human hemokinin 1, the human orthologue of mouse hemokinin 1, was more effective than mouse hemokinin 1(2-11), while endokinin D was inactive. Mouse hemokinin 1 effects were blocked by SR 140333 alone and in combination with ((S)-N-methyl-N[4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophenyl)butyl]benzamide (SR 48968) but not by SR 48968 alone. Thus the mouse hemokinins are tachykinin NK(1) receptor-preferring uterotonic agonists in non-pregnant mice but lack action at the myometrial tachykinin NK(2) receptors present in late pregnant mice.