Female Sex Hormones and Cardiac Pressure Overload Independently Contribute to the Cardiogenic Dementia Profile in Yucatan Miniature Swine

Inhibition of Extracellular Signal-Regulated Kinase Activity Improves Cognitive Function in Mice Subjected to Myocardial Infarction

Cognitive impairment is a commonly observed complication following myocardial infarction; however, the underlying mechanisms are still not well understood. The most recent research suggests that extracellular signal-regulated kinase (ERK) plays a critical role in the development and occurrence of cognitive dysfunction-related diseases. This study aims to explore whether the ERK inhibitor U0126 targets the ERK/Signal Transducer and Activator of Transcription 1 (STAT1) pathway to ameliorate cognitive impairment after myocardial infarction. To establish a mouse model of myocardial infarction, we utilized various techniques including Echocardiography, Hematoxylin-eosin (HE) staining, Elisa, Open field test, Elevated plus maze test, and Western blot analysis to assess mouse cardiac function, cognitive function, and signal transduction pathways. For further investigation into the mechanisms of cognitive function and signal transduction, we administered the ERK inhibitor U0126 via intraperitoneal injection. Reduced total distance and activity range were observed in mice subjected to myocardial infarction during the open field test, along with decreased exploration of the open arms in the elevated plus maze test. However, U0126 treatment exhibited a significant improvement in cognitive decline, indicating a protective effect through the inhibition of the ERK/STAT1 signaling pathway. Hence, this study highlights the involvement of the ERK/STAT1 pathway in regulating cognitive dysfunction following myocardial infarction and establishes U0126 as a promising therapeutic target.

CP55940-induced vasorelaxation is endothelial-dependent and mediated by the CB1R through NOS, COX and EDHF pathways in porcine cerebral arteries

Using swine as an experimental model, we chose to examine whether the cannabinoid receptors, e.g. CB1R and the CB2R, could affect vasomotor tone in isolated pial arteries. It was hypothesized that the CB1R would specifically mediate cerebral artery vasorelaxation in an endothelial-dependent manner. First-order pial arteries were isolated from female Landrace pigs (age = 2 months; N = 27) for wire and pressure myography. Arteries were pre-contracted with a thromboxane A₂ analogue (U-46619) and vasorelaxation in response to the CB1R and CB2R receptor mixed agonist CP55940 was examined in the following conditions: 1) untreated; 2) inhibition of the CB1R (AM251); or 3) inhibition of the CB2R receptor (AM630). The data revealed that CP55940 elicits a CB1R-dependent relaxation in pial arteries. CB1R expression was confirmed using immunoblot and immunohistochemical analyses. Subsequently, the role of different endothelial-dependent pathways in the CB1R-mediated vasorelaxation was examined using: 1) denudation (removal of the endothelium); 2) inhibition of cyclooxygenase (COX; Naproxen); 3) inhibition of nitric oxide synthase (NOS; L-NAME); 4) combined inhibition of COX + NOS. The data revealed CB1R-mediated vasorelaxation was endothelial-dependent, with contributions from COX-derived prostaglandins, NO, and endothelium-dependent hyperpolarizing factor (EDHF). Pressurized arteries underwent myogenic curves (20-100 mmHg) under the following conditions: 1) untreated; 2) inhibition of the CB1R. The data revealed CB1R inhibition increased basal myogenic tone, but not myogenic reactivity. As the vascular responses were assessed in isolated pial arteries, this work reveals that the CB1R modulates cerebrovascular tone independently of changes in brain metabolism.

Preclinical models of congestive heart failure, advantages, and limitations for application in clinical practice

Congestive heart failure (CHF) has increased over the years, in part because of recent progress in the management of chronic diseases, thus contributing to the maintenance of an increasingly aging population. CHF represents an unresolved health problem and therefore the establishment of animal models that recapitulates the complexity of CHF will become a critical element to be addressed, representing a serious challenge given the complexity of the pathogenesis of CHF itself, which is further compounded by methodological biases that depend on the animal species in use. Animal models of CHF have been developed in many different species, with different surgical procedures, all with promising results but, for the moment, unable to fully recapitulate the human disease. Large animal models often provide a more promising reality, with all the difficulties that their use entails, and which limit their performance to fewer laboratories, the costly of animal housing, animal handling, specialized facilities, skilled methodological training, and reproducibility as another important limiting factor when considering a valid animal model versus potentially better performing alternatives. In this review we will discuss the different animal models of CHF, their advantages and, above all, the limitations of each procedure with respect to effectiveness of results in terms of clinical application.

APOE4 genotype exacerbates the impact of menopause on cognition and synaptic plasticity in APOE-TR mice

The impact of sex and menopausal status in Alzheimer's disease remains understudied despite increasing evidence of greater female risk, particularly in APOE4 carriers. Utilizing female APOE-TR mice maintained on a high-fat diet background we induced ovarian failure through repeated VCD injections, to mimic human menopause. At 12 months of age, recognition memory and spatial memory were assessed using object recognition, Y-maze spontaneous alternation, and Barnes maze. A VCD*genotype interaction reduced the recognition memory (P < .05), with APOE4 VCD-treated animals unable to distinguish between novel and familiar objects. APOE4 mice displayed an additional 37% and 12% reduction in Barnes (P < .01) and Y-maze (P < .01) performance, indicative of genotype-specific spatial memory impairment. Molecular analysis indicated both VCD and genotype-related deficits in synaptic plasticity with BDNF, Akt, mTOR, and ERK signaling compromised. Subsequent reductions in the transcription factors Creb1 and Atf4 were also evident. Furthermore, the VCD*genotype interaction specifically diminished Ephb2 expression, while Fos, and Cnr1 expression reduced as a consequence of APOE4 genotype. Brain DHA levels were 13% lower in VCD-treated animals independent of genotype. Consistent with this, we detected alterations in the expression of the DHA transporters Acsl6 and Fatp4. Our results indicate that the combination of ovarian failure and APOE4 leads to an exacerbation of cognitive and neurological deficits.

The right ventricular transcriptome signature in Ossabaw swine with cardiometabolic heart failure: implications for the coronary vasculature

Heart failure (HF) patients with deteriorating right ventricular (RV) structure and function have a nearly twofold increased risk of death compared with those without. Despite the well-established clinical risk, few studies have examined the molecular signature associated with this HF condition. The purpose of this study was to integrate morphological, molecular, and functional data with the transcriptome data set in the RV of a preclinical model of cardiometabolic HF. Ossabaw swine were fed either normal diet without surgery (lean control, n = 5) or Western diet and aortic-banding (WD-AB; n = 4). Postmortem RV weight was increased and positively correlated with lung weight in the WD-AB group compared with CON. Total RNA-seq was performed and gene expression profiles were compared and analyzed using principal component analysis, weighted gene co-expression network analysis, module enrichment analysis, and ingenuity pathway analysis. Gene networks specifically associated with RV hypertrophic remodeling identified a hub gene in MAPK8 (or JNK1) that was associated with the selective induction of the extracellular matrix (ECM) component fibronectin. JNK1 and fibronectin protein were increased in the right coronary artery (RCA) of WD-AB animals and associated with a decrease in matrix metalloproteinase 14 protein, which specifically degrades fibronectin. RCA fibronectin content was correlated with increased vascular stiffness evident as a decreased elastin elastic modulus in WD-AB animals. In conclusion, this study establishes a molecular and transcriptome signature in the RV using Ossabaw swine with cardiometabolic HF. This signature was associated with altered ECM regulation and increased vascular stiffness in the RCA, with selective dysregulation of fibronectin.

The Aβ(1-38) peptide is a negative regulator of the Aβ(1-42) peptide implicated in Alzheimer disease progression

The pool of β-Amyloid (Aβ) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for Aβ peptides. We examined how a naturally occurring variant, e.g. Aβ(1-38), interacts with the AD-related variant, Aβ(1-42), and the predominant physiological variant, Aβ(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that Aβ(1-38) interacts differently with Aβ(1-40) and Aβ(1-42) and, in general, Aβ(1-38) interferes with the conversion of Aβ(1-42) to a β-sheet-rich aggregate. Functionally, Aβ(1-38) reverses the negative impact of Aβ(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an Aβ(1-42) phenotype in Caenorhabditis elegans. Aβ(1-38) also reverses any loss of MTT conversion induced by Aβ(1-40) and Aβ(1-42) in HT-22 hippocampal neurons and APOE ε4-positive human fibroblasts, although the combination of Aβ(1-38) and Aβ(1-42) inhibits MTT conversion in APOE ε4-negative fibroblasts. A greater ratio of soluble Aβ(1-42)/Aβ(1-38) [and Aβ(1-42)/Aβ(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that Aβ(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant Aβ(1-42).

Large Animal Models of Heart Failure: A Translational Bridge to Clinical Success

•

Preclinical large animal models play a critical and expanding role in translating basic science findings to the development and clinical approval of novel cardiovascular therapeutics.

•

This state-of-the-art review outlines existing methodologies and physiological phenotypes of several HF models developed in large animals. A comprehensive list of porcine, ovine, and canine models of disease are presented, and the translational importance of these studies to clinical success is highlighted through a brief overview of recent devices approved by the FDA alongside associated clinical trials and preclinical animal reports.

•

Increasing the use of large animal models of HF holds significant potential for identifying new mechanisms underlying this disease and providing valuable information regarding the safety and efficacy of new therapies, thus, improving physiological and economical translation of animal research to the successful treatment of human HF.

Preclinical large animal models of heart failure (HF) play a critical and expanding role in translating basic science findings to the development and clinical approval of novel therapeutics and devices. The complex combination of cardiovascular events and risk factors leading to HF has proved challenging for the development of new treatments for these patients. This state-of-the-art review presents historical and recent studies in porcine, ovine, and canine models of HF and outlines existing methodologies and physiological phenotypes. The translational importance of large animal studies to clinical success is also highlighted with an overview of recent devices approved by the Food and Drug Administration, together with preclinical HF animal studies used to aid both development and safety and/or efficacy testing. Increasing the use of large animal models of HF holds significant potential for identifying the novel mechanisms underlying the clinical condition and to improving physiological and economical translation of animal research to successfully treat human HF.

Healthy brain, healthy life: a review of diet and exercise interventions to promote brain health and reduce Alzheimer's disease risk

With the world's population aging at a rapid rate, the prevalence of Alzheimer's disease (AD) has significantly increased. These statistics are alarming given recent evidence that a third of dementia cases may be preventable. The role of lifestyle factors, such as diet and exercise, can directly alter the risk of disease development. However, an understanding of the effectiveness of dietary patterns and exercise strategies to reduce AD risk or improve brain function is not fully understood. The aim of this review is to discuss the effects of diet and exercise on AD risk. Key components of the Western and Mediterranean diets are discussed in relation to AD progression, as well as how physical activity promotes brain health. Components of the Western diet (saturated fatty acids and simple carbohydrates) are detrimental to the brain, impair cognition, and increase AD pathologies. While components of the Mediterranean diet (polyunsaturated fatty acids, polyphenols, and antioxidants) are considered to be neuroprotective. Exercise can significantly reduce the risk of AD; however, specific exercise recommendations for older adults are limited and optimal intensity, duration, and type remains unknown. This review highlights important modifiable risk factors for AD and points out potential avenues for future research. Novelty Diet and exercise are modifiable factors that can improve brain health and reduce the risk of AD. Polyunsaturated fatty acids, polyphenols, and antioxidants are neuroprotective. Exercise reduces neuroinflammation, improves brain insulin sensitivity, and increases brain derived neurotrophic factor.