Influence of acetazolamide on AQP1 gene expression in testis and on sperm count/motility in epididymis of rats

Aquaporins and (in)fertility: More than just water transport

Aquaporins (AQPs) are a family of channel proteins that facilitate the transport of water and small solutes across biological membranes. They are widely distributed throughout the organism, having a number of key functions, some of them unexpected, both in health and disease. Among the various diseases in which AQPs are involved, infertility has been overlooked. According to the World Health Organization (WHO) infertility is a global public health problem with one third of the couples suffering from subfertility or even infertility due to male or female factors alone or combined. Thus, there is an urgent need to unveil the molecular mechanisms that control gametes production, maturation and fertilization-related events, to more specifically determine infertility causes. In addition, as more couples seek for fertility treatment through assisted reproductive technologies (ART), it is pivotal to understand how these techniques can be improved. AQPs are heterogeneously expressed throughout the male and female reproductive tracts, highlighting a possible regulatory role for these proteins in conception. In fact, their function, far beyond water transport, highlights potential intervention points to enhance ART. In this review we discuss AQPs distribution and structural organization, functions, and modulation throughout the male and female reproductive tracts and their relevance to the reproductive success. We also highlight the most recent advances and research trends regarding how the different AQPs are involved and regulated in specific mechanisms underlying (in)fertility. Finally, we discuss the involvement of AQPs in ART-related processes and how their handling can lead to improvement of infertility treatment.

Psychotropics and Male Reproduction

Psychotropic drugs, including antidepressants, antipsychotics, and anticonvulsants, all have negative effects on sexual function and semen quality. These adverse events vary among men and are less pronounced for some medications, allowing their effects to be managed to some extent. Use of specific serotonin reuptake inhibitors (SSRIs) is prevalent in men of reproductive age; and application to treat premature ejaculation increases the number of young men on SSRI therapy. Oxidative damage to sperm can result from prolonged residence in the male reproductive tract. The increase in ejaculatory latency seen with SSRIs likely underlies some of their negative effects on semen quality, including higher sperm DNA fragmentation, seen in all SSRIs evaluated thus far. These medications increase prolactin (PRL) levels in some men, and this is often credited with inhibitory effects on male reproduction; however, testosterone levels are generally normal, reducing the likelihood of direct HPG axis inhibition by PRL. The tricyclic antidepressants have also been shown to increase PRL levels in some studies but not in others. The exception is the tricyclic antidepressant clomipramine, which profoundly increases PRL levels and may depress semen quality. Other antidepressants modulating synaptic levels of serotonin, norepinephrine, and/or dopamine may have toxicity similar to SSRIs, but most have not been evaluated. In limited studies, norepinephrine-dopamine reuptake inhibitors (NDRIs) and serotonin agonist/reuptake inhibitors (SARIs) have had minimal effects on PRL levels and on sexual side effects. Antipsychotic medications increase PRL, decrease testosterone, and increase sexual side effects, including ejaculatory dysfunction. The greatest evidence is for chlorpromazine, haloperidol, reserpine, risperidone, and thioridazine, with less effects seen with aripiprazole and clozapine. Remarkably few studies have looked at antipsychotic effects on semen quality, and this is an important knowledge gap in reproductive pharmacology. Lithium increases PRL and LH levels and decreases testosterone although this is informed by few studies. The anticonvulsants, many used for other indications, generally decrease free or bioavailable testosterone with variable effects on the other reproductive hormones. Valproate, carbamazepine, oxcarbazepine, and levetiracetam decrease semen quality; other anticonvulsants have not been investigated for this adverse reaction. Studies are required evaluating endpoints of pregnancy and offspring health for psychotropic medications.

Multiplicity of cerebrospinal fluid functions: New challenges in health and disease

This review integrates eight aspects of cerebrospinal fluid (CSF) circulatory dynamics: formation rate, pressure, flow, volume, turnover rate, composition, recycling and reabsorption. Novel ways to modulate CSF formation emanate from recent analyses of choroid plexus transcription factors (E2F5), ion transporters (NaHCO3 cotransport), transport enzymes (isoforms of carbonic anhydrase), aquaporin 1 regulation, and plasticity of receptors for fluid-regulating neuropeptides. A greater appreciation of CSF pressure (CSFP) is being generated by fresh insights on peptidergic regulatory servomechanisms, the role of dysfunctional ependyma and circumventricular organs in causing congenital hydrocephalus, and the clinical use of algorithms to delineate CSFP waveforms for diagnostic and prognostic utility. Increasing attention focuses on CSF flow: how it impacts cerebral metabolism and hemodynamics, neural stem cell progression in the subventricular zone, and catabolite/peptide clearance from the CNS. The pathophysiological significance of changes in CSF volume is assessed from the respective viewpoints of hemodynamics (choroid plexus blood flow and pulsatility), hydrodynamics (choroidal hypo- and hypersecretion) and neuroendocrine factors (i.e., coordinated regulation by atrial natriuretic peptide, arginine vasopressin and basic fibroblast growth factor). In aging, normal pressure hydrocephalus and Alzheimer's disease, the expanding CSF space reduces the CSF turnover rate, thus compromising the CSF sink action to clear harmful metabolites (e.g., amyloid) from the CNS. Dwindling CSF dynamics greatly harms the interstitial environment of neurons. Accordingly the altered CSF composition in neurodegenerative diseases and senescence, because of adverse effects on neural processes and cognition, needs more effective clinical management. CSF recycling between subarachnoid space, brain and ventricles promotes interstitial fluid (ISF) convection with both trophic and excretory benefits. Finally, CSF reabsorption via multiple pathways (olfactory and spinal arachnoidal bulk flow) is likely complemented by fluid clearance across capillary walls (aquaporin 4) and arachnoid villi when CSFP and fluid retention are markedly elevated. A model is presented that links CSF and ISF homeostasis to coordinated fluxes of water and solutes at both the blood-CSF and blood-brain transport interfaces.

OUTLINE

1 Overview2 CSF formation2.1 Transcription factors2.2 Ion transporters2.3 Enzymes that modulate transport2.4 Aquaporins or water channels2.5 Receptors for neuropeptides3 CSF pressure3.1 Servomechanism regulatory hypothesis3.2 Ontogeny of CSF pressure generation3.3 Congenital hydrocephalus and periventricular regions3.4 Brain response to elevated CSF pressure3.5 Advances in measuring CSF waveforms4 CSF flow4.1 CSF flow and brain metabolism4.2 Flow effects on fetal germinal matrix4.3 Decreasing CSF flow in aging CNS4.4 Refinement of non-invasive flow measurements5 CSF volume5.1 Hemodynamic factors5.2 Hydrodynamic factors5.3 Neuroendocrine factors6 CSF turnover rate6.1 Adverse effect of ventriculomegaly6.2 Attenuated CSF sink action7 CSF composition7.1 Kidney-like action of CP-CSF system7.2 Altered CSF biochemistry in aging and disease7.3 Importance of clearance transport7.4 Therapeutic manipulation of composition8 CSF recycling in relation to ISF dynamics8.1 CSF exchange with brain interstitium8.2 Components of ISF movement in brain8.3 Compromised ISF/CSF dynamics and amyloid retention9 CSF reabsorption9.1 Arachnoidal outflow resistance9.2 Arachnoid villi vs. olfactory drainage routes9.3 Fluid reabsorption along spinal nerves9.4 Reabsorption across capillary aquaporin channels10 Developing translationally effective models for restoring CSF balance11 Conclusion.

Carbonic Anhydrase Regulate Endometrial Gland Development in the Neonatal Uterus1

Carbonic anhydrases (CAs) are zinc metalloenyzmes that catalyze the reversible conversion of carbon dioxide to carbonic acid and are involved in respiration, calcification, acid-base balance, and formation of fluids. Transcriptional profiling of the developing neonatal mouse uterus detected expression of Car1, Car2, Car11, and Car13 between Postnatal Days (PNDs) 3 and 18. In the neonatal mouse uterus, Car2 and Car11 mRNAs were predominantly localized in endometrial epithelial and stromal cells, respectively, whereas Car13 mRNA was detected in both epithelia and stroma. CAR2 protein was detected primarily in the endometrial epithelia and from PND 3 to PND 18 in the uteri of neonatal mice. To determine whether CA regulated uterine development, neonatal mice were treated s.c. with acetazolamide, a CA inhibitor, from PND 3 to PND 18. Treatment with acetazolamide decreased CA activity in the uterus and the number of endometrial glands without apparent effects on differentiation of the stroma or myometrium. In the neonatal sheep uterus, CA2 mRNA was initially expressed at birth (PND 0) in the endometrial luminal epithelium and was predominantly expressed in the developing glandular epithelium from PND 7 to PND 56. These results support the hypothesis that CA has a functional role in endometrial gland development during postnatal uterine morphogenesis.

Immunoexpression of aquaporin-1 in adolescent varicocele testes: Possible significance for fluid reabsorption

OBJECTIVES

To investigate the immunoexpression of aquaporin-1 (AQP-1), a major transmembrane water channel, in high-grade varicocele testes, which are known to imply an unbalanced transmembrane water flow, in both tubular and extratubular compartments.

METHODS

Light microscopy and AQP-1 immunohistologic examination were carried out on incisional testicular biopsies from 20 adolescent boys, aged 13 to 18 years, with grade 2 or 3 idiopathic varicocele. Testicular tissue from 4 autopsied subjects of matched age were also investigated as parallel controls.

RESULTS

At microscopic examination, the tubular lumina and extracellular matrix were expanded and venular profiles dilated. Cytoplasmic vacuoles were frequent in the Sertoli cells, spermatogonia, and spermatocytes, together with premature sloughing of germ cells and residual cytoplasmic droplets inside the spermatozoa, if present. Diffuse AQP-1 positivity occurred at venular endothelial cell membranes and, unexpectedly, at the cell membranes of the Sertoli cells, diploid germ cells, and haploid cells. In the control testes, focal AQP-1 immunolabeling was confined to the microvessel endothelial cells, without any positive reaction in the tubular or extratubular compartments.

CONCLUSIONS

This is the first report showing AQP-1 cell expression in adolescent varicocele testes in both tubular and extratubular compartments. It was associated with the main histologic features of unbalanced water flow in the tubular and interstitial compartments of the testis. Immunocytochemical patterns revealed AQP-1 as a possible critical reabsorption factor, acting to reduce abnormal fluid retention in endotubular cells and the extracellular matrix and, to a lesser extent, in Leydig cells.

LOCALIZATION OF AQUAPORIN-7 IN HUMAN TESTIS AND EJACULATED SPERM: POSSIBLE INVOLVEMENT IN MAINTENANCE OF SPERM QUALITY

PURPOSE

We have previously reported the expression of aquaporin-7 (AQP7) in the rat testis and cloned human AQP7 from the testicular cDNA library. However, to our knowledge the spatial expression pattern and biological roles of AQP7 remain to be elucidated in humans.

MATERIALS AND METHODS

We investigated AQP7 expression in the human testis and ejaculated sperm from fertile men and from infertile patients.

RESULTS

AQP7 was expressed at the tail of spermatids and spermatozoa in the human testis. AQP7 protein was also detected at the middle piece and the anterior tale portion of ejaculated sperm. However, some infertile patients lacked AQP7 expression in ejaculated sperm, although all fertile men expressed AQP7 protein. The motility rate of AQP7 negative sperm was significantly lower than that of AQP7 positive sperm, while the sperm concentration was not different between AQP7 positive and negative subjects.

CONCLUSIONS

AQP7 shows a spatial expression pattern in the human testis. AQP7 may be involved in the maintenance of sperm motility. Furthermore, a lack of AQP7 expression in sperm may be an underlying mechanism of male infertility.

Toxicogenomic difference between diethylstilbestrol and 17?-estradiol in mouse testicular gene expression by neonatal exposure

In this study, we investigated the effects of neonatal exposure to exogenous estrogen (diethylstilbestrol: DES, 17beta-estradiol: E2) on testicular gene expressions. Male C57BL/6J mice, 1 day after birth, were subcutaneously injected with DES or E2 (3 micrograms/mouse/day) for 5 days, and then they were raised for 8 weeks. In morphological observation of 8-week-old mice testes, spermatozoa were absent from many seminiferous tubules in DES-treated mice testes, but there was no change in E2-treated mice testes. Analysis of in-house cDNA microarray (mouse cDNA 889 genes) revealed that 17 genes were altered in DES-treated mice testes at 8 weeks of age, compared to each control. Real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) analysis of these genes revealed that some genes, which were changed in E2-treated testis, were the same as in DES-treated testis, whereas in other cases there was a difference between DES-treated and E2-treated testis. The present results suggest that each exogenous estrogenic compound has both a common gene expression change pattern and its own testicular gene expression change pattern. Mol. Reprod. Dev. 67: 19-25, 2004.