Treatment and Survival Among Patients With Colorectal Cancer in Sub-Saharan Africa: A Multicentric Population-Based Follow-Up Study.

BACKGROUND: The burden of colorectal cancer (CRC) is increasing in Sub-Saharan Africa (SSA). However, little is known about CRC treatment and survival in the region. METHODS: A random sample of 653 patients with CRC diagnosed from 2011 to 2015 was obtained from 11 population-based cancer registries in SSA. Information on clinical characteristics, treatment, and/or vital status was obtained from medical records in treating hospitals for 356 (54%) of the patients ("traced cohort"). Concordance of CRC treatment with NCCN Harmonized Guidelines for SSA was assessed. A Cox proportional hazards model was used to examine the association between survival and human development index (HDI). RESULTS: Of the 356 traced patients with CRC, 51.7% were male, 52.8% were from countries with a low HDI, 55.1% had colon cancer, and 73.6% were diagnosed with nonmetastatic (M0) disease. Among the patients with M0 disease, however, only 3.1% received guideline-concordant treatment, 20.6% received treatment with minor deviations, 31.7% received treatment with major deviations, and 35.1% received no treatment. The risk of death in patients who received no cancer-directed therapy was 3.49 (95% CI, 1.83-6.66) times higher than in patients who received standard treatment or treatment with minor deviations. Similarly, the risk of death in patients from countries with a low HDI was 1.67 (95% CI, 1.07-2.62) times higher than in those from countries with a medium HDI. Overall survival at 1 and 3 years was 70.9% (95% CI, 65.5%-76.3%) and 45.3% (95% CI, 38.9%-51.7%), respectively. CONCLUSIONS: Fewer than 1 in 20 patients diagnosed with potentially curable CRC received standard of care in SSA, reinforcing the need to improve healthcare infrastructure, including the oncology and surgical workforce.

Colorectal cancer survival in sub-Saharan Africa by age, stage at diagnosis and Human Development Index: A population-based registry study.

There are limited population-based survival data for colorectal cancer (CRC) in sub-Saharan Africa. Here, 1707 persons diagnosed with CRC from 2005 to 2015 were randomly selected from 13 population-based cancer registries operating in 11 countries in sub-Saharan Africa. Vital status was ascertained from medical charts or through next of kin. 1-, 3- and 5-year overall and relative survival rates for all registries and for each registry were calculated using the Kaplan-Meier estimator. Multivariable analysis was used to examine the associations of 5-year relative survival with age at diagnosis, stage and country-level Human Development Index (HDI). Observed survival for 1448 patients with CRC across all registries combined was 72.0% (95% CI 69.5-74.4%) at 1 year, 50.4% (95% CI 47.6-53.2%) at 3 years and 43.5% (95% CI 40.6-46.3%) at 5 years. We estimate that relative survival at 5 years in these registry populations is 48.2%. Factors associated with poorer survival included living in a country with lower HDI, late stage at diagnosis and younger or older age at diagnosis (<50 or ≥70 years). For example, the risk of death was 1.6 (95% CI 1.2-2.1) times higher for patients residing in medium-HDI and 2.7 (95% CI 2.2-3.4) times higher for patients residing in low-HDI compared to those residing in high-HDI countries. Survival for CRC remains low in sub-Saharan African countries, though estimates vary considerably by HDI. Strengthening health systems to ensure access to prevention, early diagnosis and appropriate treatment is critical in improving outcomes of CRC in the region.

Presentation, patterns of care, and outcomes of patients with prostate cancer in sub-Saharan Africa: A population-based registry study.

BACKGROUND: Although prostate cancer (PCa) is the most commonly diagnosed cancer in men of sub-Saharan Africa (SSA), little is known about its management and survival. The objective of the current study was to describe the presentation, patterns of diagnosis, treatment, and survival of patients with PCa in 10 countries of SSA. METHODS: In this observational registry study with data collection from 2010 to 2018, the authors drew a random sample of 738 patients with PCa who were registered in 11 population-based cancer registries. They described proportions of patients receiving recommended care and presented survival estimates. Multivariable Cox regression was used to calculate hazard ratios comparing the survival of patients with and without cancer-directed therapies (CDTs). RESULTS: The study included 693 patients, and tumor characteristics and treatment information were available for 365 patients, 37.3% of whom had metastatic disease. Only 11.2% had a complete diagnostic workup for risk stratification. Among the nonmetastatic patients, 17.5% received curative-intent therapy, and 27.5% received no CDT. Among the metastatic patients, 59.6% received androgen deprivation therapy. The 3- and 5-year age-standardized relative survival for 491 patients with survival time information was 58.8% (95% confidence interval [CI], 48.5%-67.7%) and 56.9% (95% CI, 39.8%-70.9%), respectively. In a multivariable analysis, survival was considerably poorer among patients without CDT versus those with therapy. CONCLUSIONS: This study shows that a large proportion of patients with PCa in SSA are not staged or are insufficiently staged and undertreated, and this results in unfavorable survival. These findings reemphasize the need for improving diagnostic workup and access to care in SSA in order to mitigate the heavy burden of the disease in the region.

Prostate cancer survival in sub-Saharan Africa by age, stage at diagnosis, and human development index: a population-based registry study.

OBJECTIVES: To estimate observed and relative survival of prostate cancer patients in sub-Saharan Africa (SSA) and to examine the influence of age, stage at diagnosis and the Human Development Index (HDI). PATIENTS AND METHODS: In this comparative registry study, we selected a random sample of 1752 incident cases of malign prostatic neoplasm from 12 population-based cancer registries from 10 SSA countries, registered between 2005 and 2015. We analyzed the data using Kaplan-Meier and Ederer II methods to obtain outcome estimates and flexible Poisson regression modeling to calculate the excess hazards of death RESULTS: For the 1406 patients included in the survival analyses, 763 deaths occurred during 3614 person-years of observation. Of patients with known stage, 45.2% had stage IV disease, 31.2% stage III and only 23.6% stage I and II. The 1 and 5-year relative survival for the entire cohort was 78.0% (75.4-80.7) and 60.0% (55.7-64.6), while varying between the registries. Late presentation was associated with increased excess hazards and a 0.1 increase in the HDI was associated with a 20% lower excess hazard of death, while for age at diagnosis no association was found. CONCLUSIONS: We found poor survival of SSA prostatic tumor patients, as well as high proportions of late stage presentation, which are associated with inferior outcome. This calls for investment in health-care systems and action regarding projects to raise awareness among the population to achieve earlier diagnosis and improve survival.

Breast cancer survival in sub-Saharan Africa by age, stage at diagnosis and human development index: A population-based registry study.

Breast cancer is the leading cancer diagnosis and second most common cause of cancer deaths in sub-Saharan Africa (SSA). Yet, there are few population-level survival data from Africa and none on the survival differences by stage at diagnosis. Here, we estimate breast cancer survival within SSA by area, stage and country-level human development index (HDI). We obtained data on a random sample of 2,588 breast cancer incident cases, diagnosed in 2008-2015 from 14 population-based cancer registries in 12 countries (Benin, Cote d'Ivoire, Ethiopia, Kenya, Mali, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Uganda and Zimbabwe) through the African Cancer Registry Network. Of these, 2,311 were included for survival analyses. The 1-, 3- and 5-year observed and relative survival (RS) were estimated by registry, stage and country-level HDI. We equally estimated the excess hazards adjusting for potential confounders. Among patients with known stage, 64.9% were diagnosed in late stages, with 18.4% being metastatic at diagnosis. The RS varied by registry, ranging from 21.6%(8.2-39.8) at Year 3 in Bulawayo to 84.5% (70.6-93.5) in Namibia. Patients diagnosed at early stages had a 3-year RS of 78% (71.6-83.3) in contrast to 40.3% (34.9-45.7) at advanced stages (III and IV). The overall RS at Year 1 was 86.1% (84.4-87.6), 65.8% (63.5-68.1) at Year 3 and 59.0% (56.3-61.6) at Year 5. Age at diagnosis was not independently associated with increased mortality risk after adjusting for the effect of stage and country-level HDI. In conclusion, downstaging breast cancer at diagnosis and improving access to quality care could be pivotal in improving breast cancer survival outcomes in Africa.

Cervical cancer survival in sub-Saharan Africa by age, stage at diagnosis and Human Development Index: A population-based registry study.

Cervical cancer is the leading cause of cancer death in African women. We sought to estimate population-based survival and evaluate excess hazards for mortality in African women with cervical cancer, examining the effects of country-level Human Development Index (HDI), age and stage at diagnosis. We selected a random sample of 2760 incident cervical cancer cases, diagnosed in 2005 to 2015 from 13 population-based cancer registries in 11 countries (Benin, Cote d'Ivoire, Ethiopia, Kenya, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Uganda and Zimbabwe) through the African Cancer Registry Network. Of these, 2735 were included for survival analyses. The 1-, 3- and 5-year observed and relative survival were estimated by registry, stage and country-level HDI. We used flexible Poisson regression models to estimate the excess hazards for death adjusting for age, stage and HDI. Among patients with known stage, 65.8% were diagnosed with Stage III-IV disease. The 5-year relative survival for Stage I-II cervical cancer in high HDI registry areas was 67.5% (42.1-83.6) while it was much lower (42.2% [30.6-53.2]) for low HDI registry areas. Independent predictors of mortality were Stage III-IV disease, medium to low country-level HDI and age >65 years at cervical cancer diagnosis. The average relative survival from cervix cancer in the 11 countries was 69.8%, 44.5% and 33.1% at 1, 3 and 5 years, respectively. Factors contributing to the HDI (such as education and a country's financial resources) are critical for cervical cancer control in SSA and there is need to strengthen health systems with timely and appropriate prevention and treatment programmes.

Compartmentalized PDE4A5 Signaling Impairs Hippocampal Synaptic Plasticity and Long-Term Memory.

UNLABELLED: Alterations in cAMP signaling are thought to contribute to neurocognitive and neuropsychiatric disorders. Members of the cAMP-specific phosphodiesterase 4 (PDE4) family, which contains >25 different isoforms, play a key role in determining spatial cAMP degradation so as to orchestrate compartmentalized cAMP signaling in cells. Each isoform binds to a different set of protein complexes through its unique N-terminal domain, thereby leading to targeted degradation of cAMP in specific intracellular compartments. However, the functional role of specific compartmentalized PDE4 isoforms has not been examined in vivo Here, we show that increasing protein levels of the PDE4A5 isoform in mouse hippocampal excitatory neurons impairs a long-lasting form of hippocampal synaptic plasticity and attenuates hippocampus-dependent long-term memories without affecting anxiety. In contrast, viral expression of a truncated version of PDE4A5, which lacks the unique N-terminal targeting domain, does not affect long-term memory. Further, overexpression of the PDE4A1 isoform, which targets a different subset of signalosomes, leaves memory undisturbed. Fluorescence resonance energy transfer sensor-based cAMP measurements reveal that the full-length PDE4A5, in contrast to the truncated form, hampers forskolin-mediated increases in neuronal cAMP levels. Our study indicates that the unique N-terminal localization domain of PDE4A5 is essential for the targeting of specific cAMP-dependent signaling underlying synaptic plasticity and memory. The development of compounds to disrupt the compartmentalization of individual PDE4 isoforms by targeting their unique N-terminal domains may provide a fruitful approach to prevent cognitive deficits in neuropsychiatric and neurocognitive disorders that are associated with alterations in cAMP signaling. SIGNIFICANCE STATEMENT: Neurons exhibit localized signaling processes that enable biochemical cascades to be activated selectively in specific subcellular compartments. The phosphodiesterase 4 (PDE4) family coordinates the degradation of cAMP, leading to the local attenuation of cAMP-dependent signaling pathways. Sleep deprivation leads to increased hippocampal expression of the PDE4A5 isoform. Here, we explored whether PDE4A5 overexpression mimics behavioral and synaptic plasticity phenotypes associated with sleep deprivation. Viral expression of PDE4A5 in hippocampal neurons impairs long-term potentiation and attenuates the formation of hippocampus-dependent long-term memories. Our findings suggest that PDE4A5 is a molecular constraint on cognitive processes and may contribute to the development of novel therapeutic approaches to prevent cognitive deficits in neuropsychiatric and neurocognitive disorders that are associated with alterations in cAMP signaling.

Cancer survival in sub-Saharan Africa (SURVCAN-3): a population-based study.

BACKGROUND: The Cancer Survival in Africa, Asia, and South America project (SURVCAN-3) of the International Agency for Research on Cancer aims to fill gaps in the availability of population-level cancer survival estimates from countries in these regions. Here, we analysed survival for 18 cancers using data from member registries of the African Cancer Registry Network across 11 countries in sub-Saharan Africa. METHODS: We included data on patients diagnosed with 18 cancer types between Jan 1, 2005, and Dec 31, 2014, from 13 population-based cancer registries in Cotonou (Benin), Abidjan (CÔte d'Ivoire), Addis Ababa (Ethiopia), Eldoret and Nairobi (Kenya), Bamako (Mali), Mauritius, Namibia, Seychelles, Eastern Cape (South Africa), Kampala (Uganda), and Bulawayo and Harare (Zimbabwe). Patients were followed up until Dec 31, 2018. Patient-level data including cancer topography and morphology, age and date at diagnosis, vital status, and date of death (if applicable) were collected. The follow-up (survival) time was measured from the date of incidence until the date of last contact, the date of death, or until the end of the study, whichever occurred first. We estimated the 1-year, 3-year, and 5-year survival (observed, net, and age-standardised net survival) by sex, cancer type, registry, country, and human development index (HDI). 1-year and 3-year survival data were available for all registries and all cancer sites, whereas availability of 5-year survival data was slightly more variable; thus to provide medium-term survival prospects, we have focused on 3-year survival in the Results section. FINDINGS: 10 500 individuals from 13 population-based cancer registries in 11 countries were included in the survival analyses. 9177 (87·4%) of 10 500 cases were morphologically verified. Survival from cancers with a high burden and amenable to prevention was poor: the 3-year age-standardised net survival was 52·3% (95% CI 49·4-55·0) for cervical cancer, 18·1% (11·5-25·9) for liver cancer, and 32·4% (27·5-37·3) for lung cancer. Less than half of the included patients were alive 3 years after a cancer diagnosis for eight cancer types (oral cavity, oesophagus, stomach, larynx, lung, liver, non-Hodgkin lymphoma, and leukaemia). There were differences in survival for some cancers by sex: survival was longer for females with stomach or lung cancer than males with stomach or lung cancer, and longer for males with non-Hodgkin lymphomas than females with non-Hodgkin lymphomas. Survival did not differ by country-level HDI for cancers of the oral cavity, oesophagus, liver, thyroid, and for Hodgkin lymphoma. INTERPRETATION: For cancers for which population-level prevention strategies exist, and with relatively poor prognosis, these estimates highlight the urgent need to upscale population-level prevention activities in sub-Saharan Africa. These data are vital for providing the knowledge base for advocacy to improve access to prevention, diagnosis, and care for patients with cancers in sub-Saharan Africa. FUNDING: Vital Strategies, the Martin-Luther-University Halle-Wittenberg, and the International Agency for Research on Cancer. TRANSLATIONS: For the French and Portuguese translations of the abstract see Supplementary Materials section.

The evaluation of AZ66, an optimized sigma receptor antagonist, against methamphetamine-induced dopaminergic neurotoxicity and memory impairment in mice.

Sigma (σ) receptors have recently been identified as potential targets for the development of novel therapeutics aimed at mitigating the effects of methamphetamine. Particularly, σ receptors are believed to mitigate some of the neurotoxic effects of methamphetamine through modulation of dopamine, dopamine transporters and body temperature. Furthermore, recent evidence suggests that targeting σ receptors may prevent cognitive impairments produced by methamphetamine. In the present study, an optimized σ receptor antagonist, AZ66, was evaluated against methamphetamine-induced neurotoxicity and cognitive dysfunction. AZ66 was found to be highly selective for σ receptors compared to 64 other sites tested. Pretreatment of male, Swiss Webster mice with i.p. dosing of AZ66 significantly attenuated methamphetamine-induced striatal dopamine depletions, striatal dopamine transporter reductions and hyperthermia. Additionally, neurotoxic dosing with methamphetamine caused significant memory impairment in the object recognition test, which was attenuated when animals were pretreated with AZ66; similar trends were observed in the step-through passive avoidance test. Taken together, these results suggest that targeting σ receptors may provide neuroprotection against the neurotoxicity and cognitive impairments produced by methamphetamine.

Analysis of the Breast Cancer Journey in Namibia.

Importance: Breast cancer (BC) is the leading cancer among women in Namibia. Examining the BC journey in this multiracial country where inequalities remain large is needed to inform effective interventions to reduce BC mortality. Objective: To describe the entire BC journey of Namibian women by race, utilizing the World Health Organization Global Breast Cancer Initiative (GBCI) framework. Design, Setting, and Participants: This cohort study used the Namibian subset of the African Breast Cancer-Disparities in Outcomes prospective cohort. Participants were all Namibian residents with confirmed incident BC who presented at the main national public oncology center of the Windhoek Central Hospital (WCH). Follow-up started from recruitment (September 8, 2014, to October 5, 2016) and ended up to 3 years after diagnosis (December 13, 2014, to September 27, 2019). Data analysis was conducted from June 2022 to August 2023. Exposures: Participants' self-reported ethnicities were aggregated into 3 population groups: Black, mixed ancestry, and White. Main Outcomes and Measures: Three-year overall survival (OS) was examined using Cox models, and summary statistics were used to describe women's BC journey, including GBCI pillar key performance indicators: (1) early stage (TNM I or II) diagnosis (population benchmark ≥60%), (2) prompt diagnosis, ie, 60 days or less to first health care practitioner visit (population benchmark 100%), and (3) completion of recommended multimodal treatment (MT, ie, surgery plus chemotherapy) (population benchmark ≥80%). Results: Of 405 women, there were 300 (74%) Black (mean [SD] age, 53 [15] years), 49 (12%) mixed ancestry (mean [SD] age, 53 [7] years), and 56 (14%) White (mean [SD] age, 59 [12] years) patients. Three-year OS was lowest in Black women (60% [95% CI, 54%-66%]; mixed ancestry: 80% [95% CI, 65%-89%]; White: 89% [95% CI, 77%-95%]), who had lower prevalence of early stage diagnosis (Black: 37% [95% CI, 31%-42%]; mixed ancestry and White: 75% [95% CI, 66%-83%]) and timely diagnosis (Black: 60% [95% CI, 54%-66%]; mixed ancestry and White: 77% [95% CI, 69%-85%]), while MT completion (Black: 53% [95% CI, 46%-59%]; mixed ancestry and White: 63% [95% CI, 50%-73%]) was low in all women. Conclusions and Relevance: In this cohort study of 405 Namibian residents with BC, marked racial disparities in survival were paralleled by inequities all along the BC journey. To improve BC survival, interventions are needed to promote earlier diagnosis in Black Namibian women and to increase MT initiation and completion in all women.

Plasma radiofrequency preceded by pressure recording enhances success for treating sleep-related breathing disorders.

OBJECTIVES: Sleep-related breathing disorders (SRBD) that cannot be treated conservatively are commonly treated using uvulopalatopharyngoplasty, although success rates are generally less than 70%. The purpose of this study was to assess a plasma-mediated radiofrequency (RF)-based coblation assisted upper airway procedure (CAUP) to treat SRBD patients determined to have obstruction localized to the upper (mid)-pharyngeal region. STUDY DESIGN: Prospective case series (n = 40). METHODS: Six patients had socially bothersome snoring, and 34 patients had mild to moderate sleep apnea (apnea/hypopnea index [AHI] <20), with the primary level of obstruction (>50%) within the upper pharyngeal region as determined using whole night recordings, including airway pressure fluctuation monitoring (ApneaGraph, MRA-Medical Ltd, Gloucestershire, UK). CAUP consisted of making a lateral palatal incision, ablating three upward channels on each side of the midline (fan-shaped) into the soft palate using a plasma mediated RF-based device (ArthroCare Corporation, Austin, TX), and performing a partial uvulectomy. Clinical outcomes included the Epworth Sleepiness Scale (ESS), partner rating of snoring using a visual analogue scale (VAS), and night-time apnea and hypopnea events (AHI, hypopnea index [HI], apnea index [AI]). RESULTS: Patients were 28 to 68 (46 +/- 12) years old; 28 (70%) were male. Preoperatively, clinical assessment scores (median +/- interquartile range) were as follows: ESS (11.0 +/- 3.0), VAS (8.15 +/- 1.00), AHI (9.58 +/- 5.58), HI (9.00 +/- 5.29), AI (0.333 +/- 0.625). After CAUP, no postoperative scarring, fibrosis, or any other clinically significant side effects were observed. Postoperatively (9.1 +/- 1.5; 7-15 mo), ESS (4.0 +/- 1.0), VAS (2.70 +/- 1.38), AHI (3.75 +/- 2.92), HI (3.58 +/- 2.50), and AI (0.167 +/- 0.167) were significantly improved (P < .001). CONCLUSION: CAUP preceded by site-specific obstruction diagnosis using pressure recording is a well-tolerated outpatient treatment that is well suited for treating SRBD.

The Past, Present, and Future of Phosphodiesterase-4 Modulation for Age-Induced Memory Loss.

The purpose of this chapter is to highlight the state of progress for phosphodiesterase-4 (PDE4) modulation as a potential therapeutic for psychiatric illness, and to draw attention to particular hurdles and obstacles that must be overcome in future studies to develop PDE4-mediated therapeutics. Pathological and non-pathological related memory loss will be the focus of the chapter; however, we will at times also touch upon other psychiatric illnesses like anxiety and depression. First, we will provide a brief background of PDE4, and the rationale for its extensive study in cognition. Second, we will explore fundamental differences in individual PDE4 subtypes, and then begin to address differences between pathological and non-pathological aging. Alterations of cAMP/PDE4 signaling that occur within normal vs. pathological aging, and the potential for PDE4 modulation to combat these alterations within each context will be described. Finally, we will finish the chapter with obstacles that have hindered the field, and future studies and alternative viewpoints that need to be addressed. Overall, we hope this chapter will demonstrate the incredible complexity of PDE4 signaling in the brain, and will be useful in forming a strategy to develop future PDE4-mediated therapeutics for psychiatric illnesses.

Learning induces the translin/trax RNase complex to express activin receptors for persistent memory.

Long-lasting forms of synaptic plasticity and memory require de novo protein synthesis. Yet, how learning triggers this process to form memory is unclear. Translin/trax is a candidate to drive this learning-induced memory mechanism by suppressing microRNA-mediated translational silencing at activated synapses. We find that mice lacking translin/trax display defects in synaptic tagging, which requires protein synthesis at activated synapses, and long-term memory. Hippocampal samples harvested from these mice following learning show increases in several disease-related microRNAs targeting the activin A receptor type 1C (ACVR1C), a component of the transforming growth factor-ß receptor superfamily. Furthermore, the absence of translin/trax abolishes synaptic upregulation of ACVR1C protein after learning. Finally, synaptic tagging and long-term memory deficits in mice lacking translin/trax are mimicked by ACVR1C inhibition. Thus, we define a new memory mechanism by which learning reverses microRNA-mediated silencing of the novel plasticity protein ACVR1C via translin/trax.

Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1.

Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density.

Phosphodiesterase-4 modulation as a potential therapeutic for cognitive loss in pathological and non-pathological aging: possibilities and pitfalls.

Phosphodiesterases (PDEs) are a super family of 11 enzyme families responsible for the hydrolysis of the intracellular secondary messengers cyclic AMP (cAMP) and cyclic GMP (cGMP). PDE4, in particular, is highly expressed in brain regions involved with regulation of memory, anxiety, and depression, including the hippocampus, amygdala, and nucleus accumbens. Senescence has been shown to result in extreme dysregulation of the cAMP pathway in various brain regions. Thus, as a critical controller of intracellular cAMP levels, PDE4 may be a potential target for the treatment of senescence-related cognitive disorders, which could be pathological and/or non-pathological in origin. While there is great potential in the development of novel PDE4 inhibitors for treatment of senescent-cognition impairment, there are also currently many pitfalls that need to be overcome. PDE4 has four subfamilies (PDE4A, B, C, and D) that are differentially expressed throughout the brain and body, as well as at least 25 splice variants derived from alternative splicing and multiple promoter sites. PDE4 subtypes have been shown to have differential effects on behavior, and cAMP itself has also been shown to play a contrasting role in behavior in different brain regions. This review will focus on what is currently understood about PDE4 in aging, the potential for PDE4 modulation as a cognitive therapy, and current pitfalls and limitations that need to be overcome in the PDE4 field. Overall, furthering our understanding of this incredibly complex pathway may one day assist with the development of novel therapeutics for both pathological and non-pathological cognitive disorders associated with senescence.

Mice deficient in phosphodiesterase-4A display anxiogenic-like behavior.

RATIONALE: Phosphodiesterases (PDEs) are a super family of enzymes responsible for the halting of intracellular cyclic nucleotide signaling and may represent novel therapeutic targets for treatment of cognitive disorders. PDE4 is of considerable interest to cognitive research because it is highly expressed in the brain, particularly in the cognition-related brain regions. Recently, the functional role of PDE4B and PDE4D, two of the four PDE4 subtypes (PDE4A, B, C, and D), in behavior has begun to be identified; however, the role of PDE4A in the regulation of behavior is still unknown. OBJECTIVES: The purpose of this study was to characterize the functional role of PDE4A in behavior. METHODS: The role of PDE4A in behavior was evaluated through a battery of behavioral tests using PDE4A knockout (KO) mice; urine corticosterone levels were also measured. RESULTS: PDE4A KO mice exhibited improved memory in the step-through-passive-avoidance test. They also displayed anxiogenic-like behavior in elevated-plus maze, holeboard, light-dark transition, and novelty suppressed feeding tests. Consistent with the anxiety profile, PDE4A KO mice had elevated corticosterone levels compared with wild-type controls post-stress. Interestingly, PDE4A KO mice displayed no change in object recognition, Morris water maze, forced swim, tail suspension, and duration of anesthesia induced by co-administration of xylazine and ketamine (suggesting that PDE4A KO may not be emetic). CONCLUSIONS: These results suggest that PDE4A may be important in the regulation of emotional memory and anxiety-like behavior, but not emesis. PDE4A could possibly represent a novel therapeutic target in the future for anxiety or disorders affecting memory.

Senescent-induced dysregulation of cAMP/CREB signaling and correlations with cognitive decline.

It is well known that alongside senescence there is a gradual decline in cognitive ability, most noticeably certain kinds of memory such as working, episodic, spatial, and long term memory. However, until recently, not much has been known regarding the specific mechanisms responsible for the decline in cognitive ability with age. Over the past decades, researchers have become more interested in cAMP signaling, and its downstream transcription factor cAMP response element binding protein (CREB) in the context of senescence. However, there is still a lack of understanding on what ultimately causes the cognitive deficits observed with senescence. This review will focus on the changes in intracellular signaling in the brain, more specifically, alterations in cAMP/CREB signaling in aging. In addition, the downstream effects of altered cAMP signaling on cognitive ability with age will be further discussed. Overall, understanding the senescent-related changes that occur in cAMP/CREB signaling could be important for the development of novel drug targets for both healthy aging, and pathological aging such as Alzheimer's disease.

Inhibition of phosphodiesterase-4 decreases ethanol intake in mice.

RATIONALE: Cyclic AMP (cAMP)-protein kinase A signaling has been implicated in the regulation of ethanol consumption. Phosphodiesterase-4 (PDE4) specifically hydrolyzes cAMP and plays a critical role in controlling intracellular cAMP levels in the brain. However, the role of PDE4 in ethanol consumption remains unknown. OBJECTIVE: The objective of this study is to examine whether PDE4 was involved in regulating ethanol intake. METHODS: The two-bottle choice paradigm was used to assess intake of ethanol, sucrose, and quinine in C57BL/6J mice treated with the selective PDE4 inhibitor rolipram or Ro 20-1724; locomotor activity was also monitored using the open-field test in mice treated with rolipram. RESULTS: Administration (i.p.) of either rolipram (0.25 and 0.5 mg/kg) or Ro 20-1724 (10 mg/kg) reduced ethanol intake and preference by 60-80%, but did not alter total fluid intake. In contrast, rolipram even at the higher dose of 0.5 mg/kg was not able to affect intake of sucrose or quinine, alcohol-induced sedation, or blood ethanol elimination. At 0.5 mg/kg, rolipram did decrease locomotor activity, but the effect only lasted for approximately 40 min, which did not likely affect behavior of ethanol drinking. CONCLUSIONS: These results suggest that PDE4 is a novel target for drugs that reduce ethanol intake; PDE4 inhibitors may be used for treatment of alcohol dependence.