hip rats  (Charles River Laboratories)

Journal: iScience

Article Title: Peripheral amylin modulation rebalances brain glycolysis and Tau-Ser214 phosphorylation via cAMP-PKA signaling

doi: 10.1016/j.isci.2026.115157

Figure Lengend Snippet: Impact of amylin deficiency and human vs. mouse amylin secretion on brain glucose regulation during prediabetes-like stress (A) Timeline of diet-induced metabolic stress for comparative analyses in mice expressing mouse amylin (wild-type; WT mice), human amylin (hA ON mice) and no amylin (hA OFF mice). Mice were switched to a high fat diet at 3 months of age or maintained on regular chow and investigated at 7 months of age. (B–E) Validation of pancreatic β-cell-specific expression of the human amylin transgene and confirmation of endogenous amylin gene deletion. (B) Amylin mRNA expression levels in pancreatic tissues from hA ON , hA OFF , and WT mice, heart tissue from hA ON and hA OFF mice and pancreatic tissue from HIP rats overexpressing human amylin (positive control). NTC stands for no template control. (C) Representative confocal microscopy images of immunostaining pancreatic islets for amylin and insulin in hA ON mice on chow vs. high-fat diets. (D and E) Four months of high-fat feeding induces pancreatic hypersecretion of amylin and insulin as indicated by immunofluorescence signal intensities of insulin (D) and amylin (E) staining in islets from hA ON , hA OFF , and WT mice on chow vs. high-fat diets. (F) Brain tissue amylin levels in high-fat-fed hA ON and WT male mice vs. littermates on chow diet. (G) Schematic describing the first intermediate of glucose metabolism (glucose-6-phosphate; G6P), metabolic pathways, glycolytic amino acids, and glycolytic kinases facilitating G6P use by cells. (H–J) Comparative analyses of brain tissue G6P levels (H), glycolytic amino acids serine (Ser), glycine (Gly), and alanine (Ala) (I) and cerebral glycolytic flux (J) in hA ON , hA OFF , and WT male mice. (K) Pairwise correlation between cerebral glycolytic flux and blood glucose level in all mice investigated. Data points in (D and E) represent the mean fluorescence intensity in islets from the same mouse, n = 5–10 islets/mouse. Data are shown as individual values and mean ± s.e.m. Statistical analyses were performed using two-tail t test (D–F) and one-way ANOVA followed by Tukey’s multiple-comparisons test (H and J). Schematic A was created using BioRender. See also .

Article Snippet: transgenic rats expressing pancreatic human amylin , Charles Rivers Laboratories , HIP rats, SD-Tg (Ins2-IAPP).

Techniques: Expressing, Biomarker Discovery, Positive Control, Control, Confocal Microscopy, Immunostaining, Immunofluorescence, Staining, Fluorescence

Journal: iScience

Article Title: Peripheral amylin modulation rebalances brain glycolysis and Tau-Ser214 phosphorylation via cAMP-PKA signaling

doi: 10.1016/j.isci.2026.115157

Figure Lengend Snippet: Cerebral glycolysis impairment and AD-like pathology in rats with genetically elevated pancreatic human amylin secretion (A) Schematic of the experimental approach for assessing cerebral glycolytic flux, Aβ 40 , Aβ 42 , pTau, and total tau levels in rats expressing WT rat amylin vs. pancreatic human amylin (HIP rats) vs. amylin knockout (AKO) rats. All rats were maintained on chow diet through the endpoint (16 months of age). (B) Endpoint blood glucose concentrations in HIP, WT, and AKO rats. (C) Brain tissue amylin levels in HIP and WT rats measured at the endpoint. (D–F) Comparative analyses of brain tissue G6P levels (D), glycolytic amino acids (Ser), glycine (Gly), and alanine (Ala) (E) and cerebral glycolytic flux (F) in the same rats as in (B). (G–J) Brain tissue levels of Aβ 40 , Aβ 42 , pTau, and total Tau in the same rats as in (B). (K and L) Representative images of immunohistochemistry analysis of pTau in HIP brain tissue (K) and confocal microscopy analysis of brain sections from the same rats stained with a combination of anti-amylin and anti-pTau antibodies (L). Three sections/brain. The diagram in (A) was created using BioRender. Data are mean ± s.e.m from 7 to 10 male mice/group. Statistical analyses were performed using One-way ANOVA followed by Dunnett’s multiple-comparisons test (B and D–J) and two-tail t test (C).

Article Snippet: transgenic rats expressing pancreatic human amylin , Charles Rivers Laboratories , HIP rats, SD-Tg (Ins2-IAPP).

Techniques: Expressing, Knock-Out, Immunohistochemistry, Confocal Microscopy, Staining

Journal: Pharmacological research

Article Title: Catechol-containing compounds are a broad class of protein aggregation inhibitors: Redox state is a key determinant of the inhibitory activities

doi: 10.1016/j.phrs.2022.106409

Figure Lengend Snippet: Animal studies demonstrated that RA strongly reduced amylin amyloid islet deposition and ameliorated diabetic pathology in transgenic diabetic HIP rats. Prediabetic HIP rats (6-month-old) were treated (HIP+RA) or untreated (HIP) with dietary supplementation of 0.5% (w/w) RA in regular chow diet for 4 months. Age-matched wild-type Sprague–Dawley rats with regular chow diet served as negative controls (WT). At the end of the treatments, rats were euthanized, and pancreatic tissues and sera were collected for immunohistochemistry and biochemical analysis. (A) Representative Congo red staining demonstrated strong amyloid staining in untreated HIP rat pancreatic tissue slices (orange-red color in the islets, middle panel). Congo red staining was significantly reduced in the islets of RA-treated HIP rats with only residue staining remaining (right panel). No Congo red staining was observed in islets in control wild-type SD rats (left panel). All pancreatic islets are marked by red asterisks. These qualitative results represent multiple samples from RA-treated or untreated HIP rats or WT Sprague–Dawley controls (n = 4), and at least 50 islets from pancreatic head, body, and tail for each group were examined. Scale bar in each panel is 100 μm. (B) Representative amylin deposition in the pancreatic tissue slice using amylin antibody staining from different rat groups. Pancreatic tissue slices were stained with amylin-specific antibody (T-4157) followed by secondary antibody and NovaRED substrate (Vector Lab) treatment. Stained islets are shown in dark brown color. Islets in the pancreatic slices from untreated HIP rats were intensely stained, whereas those from RA-treated and control SD rats were only weakly stained. At least 10 tissue slices were observed from each group. Scale bar in each panel as indicated is 1 mm. (C) Serum glucose levels were quantified for each group of rats. Significant reduction of serum glucose concentration was observed, indicated by asterisks (p < 0.05 or p < 0.01) comparing the untreated HIP rats with those of RA-treated HIP rats or control SD rats. (D) Insulin levels were measured for each group of rats. Statistically lower levels of insulin were observed and indicated by asterisks (p < 0.05) comparing the untreated HIP rats with those of RA-treated HIP rats or control SD rats (n = 4).

Article Snippet: Transgenic HIP rats (RIP-HAT) and wild-type Sprague–Dawley (SD) control rats were purchased from Charles River Laboratories (Wilmington, MA).

Techniques: Transgenic Assay, Immunohistochemistry, Staining, Residue, Control, Plasmid Preparation, Concentration Assay

Journal: Cells

Article Title: An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

doi: 10.3390/cells9112475

Figure Lengend Snippet: Metabolic syndrome, T2DM and COVID-19 are multisystem diseases. This image illustrates how metabolic syndrome (MetS)/type 2 diabetes mellitus (T2DM) and coronavirus disease 2019 (COVID-19) are two multisystem diseases that can have a tremendous interaction, with multiple crosstalk when they intersect. The central “X” in this figure honors Jerry Reaven who initially coined the term Syndrome X and championed the concept that resistance to insulin-mediated glucose disposal was a characteristic of patients with T2DM and cardiovascular disease (CVD), which was later termed MetS. There are four arms to this letter X and each arm has a designated condition to further illustrate the “H” phenomenon, representing a “hyper” state, i.e., hyperlipidemia, lower left; islet β-cell hyperinsulinemia/hyperamylinemia, lower right; hypertension, upper right; hyperglycemia, upper left. Note how insulin resistance (IR) is central to each of the four arms. While each arm is important, one can note that hyperinsulinemia and hyperamylinemia are of great importance to this review, in that this arm represents the hormonal secretion by the pancreatic β-cells that have the ACE2 on their outer surface that is necessary for SARS-CoV-2 (red spiked icon with CoV-2 labeling) to enter the cells. Further, ACE2 is present on the intra-islet microcirculation capillary endothelial cells/pericytes and the peri-islet capillaries. In addition to intra-islet amyloid deposition and fibrosis, there is also peri-islet amyloid and fibrosis, redox stress oxidative/nitrosative stress (RONS) and inflammation that are in a vicious cycle with one another. MetS and T2DM are known to be associated with the renin–angiotensin–aldosterone system (RAAS) within the islet and there exists the possibility that further activation of islet RAAS may be due to the diminished ACE2/Ang(1–7)/MasR as a result of viral virion binding and contribute to ongoing remodeling over time following the recovery from COVID-19. Additionally, due the overriding effect of Ang II excess due to ACE2 binding, there will be increased vasospasm and hypoxia to the islets that may compound the COVID-19 islet injury. Endothelial activation/dysfunction due MetS, T2DM and COVID-19 may be responsible for further islet damage. Importantly, there is the known cytokine storm that could initially play a damaging role to the islet and its contents with loss of β-cells. Further, cerebrocardiovascular disease (CVD) and chronic kidney disease (CKD) together comprise the brain–heart–kidney axis that is involved when there is vascular stiffness associated with MetS and T2DM. It is very important to note that only body mass index (BMI)/obesity (not morbid obesity) turned out to be independently associated with the primary outcome of need for ventilation and/or death at 7 days post-admission in the French CORONADO study and thus implicates obesity as a major predicting phenotype associated with the need for supportive ventilation and or death as obesity is also noted to be driving MetS (lower left-hand side of figure **) see reference 21. ACE = angiotensin-converting enzyme; ACE2 = angiotensin-converting enzyme 2; AGE = advanced glycation end products; ANGII/Ang II = angiotensin II; Ang(1–7) = angiotensin 1–7; CKD = chronic kidney disease; CVD = cerebrocardiovascular disease; D-dimer = a fibrin degradation product and is named after two D fragments of the fibrin protein joined by a crosslink upon fibrinolysis; eNOS = endothelial nitric oxide synthase; ER = endoplasmic reticulum; ESRD = end-stage renal disease; FFA = free fatty acids; HPA = hypothalamic–pituitary–adrenal axis; IAPP = islet amyloid polypeptide; MasR = MAS-related G protein-coupled receptor; Mt = mitochondria; NAFLD = non-alcoholic fatty liver disease; NASH = non-alcoholic steatohepatitis; PAI-1 = plasminogen activator-1; RAGE = receptor for AGE; RBC = red blood cell; RONS = reactive oxygen and nitrogen (nitrosative stress) species; SNS = sympathetic nervous system.

Article Snippet: The human islet amyloid polypeptide (HIP) rat model was created by the transfection of Sprague–Dawley rat with the human islet amyloid polypeptide (hIAPP)-amylin gene in 2004 and initially studied by Butler AE et al. [ ].

Techniques: Labeling, Activation Assay, Binding Assay

Journal: Cells

Article Title: An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

doi: 10.3390/cells9112475

Figure Lengend Snippet: Pancreatic islet β-cells undergo a multiple hit injury with MetS/T2DM and COVID-19. This illustration depicts the close relationship of the islet capillaries and the β-cells with transmission electronic microscopic (TEM) images of the pancreatic islet capillary Panel ( A ) and the β-cell Panel ( B ) in those infected by SARS-CoV-2. Panel ( A ) depicts an islet capillary in close proximity to an islet β-cell (preclinical HIP rodent model) and notes that CoV-2 may bind not only to the endothelial cell ACE2 protein of capillary endothelial cells but may also bind to pericytes, since ACE2 has recently been found to bind to pericytes in the brain and myocardial capillary specimens especially if the EC glycocalyx barrier function has been damaged allowing SARS-CoV-2 to enter the subendothelial space. Panel ( B ) illustrates the small electron dense dots that are the insulin secretory granules (ISG) within the β-cell cytoplasm (preclinical HIP rodent model). Additionally, amylin undergoes unfolding and misfolding to form islet amyloid polypeptide (IAPP) (panel ( B )—lower right hand) when exposed to toxic oxidative stress—reactive oxygen and nitrogen (nitrosative stress) species (RONS). The early more intermediate-sized toxic amyloid oligomers (TAO) of amylin have a propensity to form membrane permeant channels in the islet β-cell plasma membrane, which allow for the entrance of calcium transients to enter the β-cell and result in not only β-cell dysfunction but also β-cell loss via apoptosis see reference 63 and 64. There is approximately a 50% decrease in β-cell function of those with T2DM and a 40–50% loss of β-cells in individuals with impaired glucose tolerance or prediabetes. Therefore, one can deduce that if there is already this much β-cell loss why SARS-CoV-2 could significantly add to this loss via SARS-CoV-2 binding to the ACE2 on β-cells (+/−) with further β-cell dysfunction, apoptosis and possibly accelerate the natural history of T2DM. Note the (+/−) regarding the presence of the ACE2 enzyme receptor since there is currently some controversy regarding its presence in pancreatic islet β-cells; see reference [ , , , ]. Notably, systemic toxic cytokines liberated from pulmonary tissues and systemic immune cells can also be related to pancreatic islet injury mechanisms. Additionally, in preclinical T2DM rodent models, there is intra-islet capillary rarefaction that may contribute to β-cell dysfunction and death see reference 66. ACE2 = angiotensin-converting enzyme 2 (orange color); β = β-cell; β-C = β-cell; Ca++ = calcium; CoV-2 = SARS-CoV-2 (spiked red icon); CL = capillary lumen; EC = endothelial cell; ECM = extracellular matrix; IA = islet amyloid; IAPP = islet amyloid polypeptide deposition (blue fibril icon); IFN-γ = interferon gamma; Il-1β = interleukin 1 beta; ISG = insulin secretory granules; MetS = metabolic syndrome; N = nucleus; Pc = pericyte; PM = plasma membrane; RONS = reactive oxygen and nitrogen (nitrosative stress) species; TAO = toxic intermediate-sized amyloid oligomers; TNFα = tumor necrosis alpha; T2DM = type 2 diabetes mellitus.

Article Snippet: The human islet amyloid polypeptide (HIP) rat model was created by the transfection of Sprague–Dawley rat with the human islet amyloid polypeptide (hIAPP)-amylin gene in 2004 and initially studied by Butler AE et al. [ ].

Techniques: Transmission Assay, Infection, Membrane, Clinical Proteomics, Cell Function Assay, Binding Assay

Journal: Cells

Article Title: An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

doi: 10.3390/cells9112475

Figure Lengend Snippet: T2DM is a progressive disease consisting of five stages in the natural history of T2DM. T2DM implicates metabolic syndrome, redox stress, islet amyloid, islet fibrosis and RAAS. T2DM is the end stage of a process that involves a definite loss of pancreatic β-cell function and β-cell apoptosis that has multiple stages (I–V) during its development of this end-stage isletopathy. This figure represents a putative model of these five stages and how they are associated with islet amyloid, islet fibrosis and involves not only a systemic cRAAS but also a local tRAAS with excess islet Ang II production. Most often, insulin resistance is associated early on in this process and relates to a central role or state of hyperinsulinemia and hyperamylinemia as noted in metabolic syndrome in . Loss of β-cell function and/or loss via apoptosis eventually develops and blood glucose levels continue to rise. Stages I–V demonstrate that T2DM is a progressive disease as in , which involves islet amyloid and islet fibrosis remodeling. Thus, the late complication of T2DM development in previous non-diabetic patients may depend on the stage of development of the individual when they develop COVID-19 in relation to the type of T2DM during the development of late complications since SARS-CoV-2 may either involve the islet and its β-cells directly or indirectly. Further, an individual that is controlled on oral medication and lifestyle modifications may indeed develop an insulin-dependent type of T2DM due to the acceleration of the underlying stage at the time of infection due to loss of β-cells and possibly due to novel hybrid forms of diabetes such as latent autoimmune diabetes in adults following COVID-19. T2DM is a heterogeneous, multifactorial spectrum disease. Therefore, not all individuals who develop T2DM will strictly follow this 5-stage roadmap in a lock-step manner. Importantly, recent findings utilizing clustering analysis for the development of T2DM and its complications are being utilized and may relate to the personalized treatment of various clusters in addition to stages I–V. See , T2DM May Be Considered a Spectrum Disease. The novel clustering analysis that is currently being utilized will add a great deal of knowledge to stages I–V [ , , ]. ANG II/Ang II = angiotensin II; AGE = advanced glycation end products; ER = endoplasmic reticulum; IAPP = islet amyloid polypeptide; IGT = impaired glucose tolerance; IR = insulin resistance; RAAS = renin–angiotensin–aldosterone system; RAGE = receptor for AGE; RONS = reactive oxygen and nitrogen (nitrosative stress) species; UPR = unfolded protein response.

Article Snippet: The human islet amyloid polypeptide (HIP) rat model was created by the transfection of Sprague–Dawley rat with the human islet amyloid polypeptide (hIAPP)-amylin gene in 2004 and initially studied by Butler AE et al. [ ].

Techniques: Cell Function Assay, Infection

Journal: Cells

Article Title: An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

doi: 10.3390/cells9112475

Figure Lengend Snippet: Normal insulin secretory granule docking in control and impaired docking to the capillary endothelium in the HIP rat models. Panels ( A – D ) illustrate the close association of β-cells to the islet capillaries, which allow for proper docking of the insulin secretory granule (ISG) (white open arrows) for absorption of insulin in the 4-month-old control Sprague–Dawley control (SDC). Magnifications and scale bars are in each image. Panel ( E ) depicts the diffuse islet amyloid deposition (asterisks) in the 4-month-old HIP rat model. This image allows one to note the impairment of ISG docking with the islet capillary. Note only the small spaces (outlined by yellow dashed lines) that are able to allow for minimal docking of ISGs. Note how the ISGs come to the peri-capillary islet amyloid and appear to be abruptly quarantined without access to the islet capillaries. These findings would fall into stages II and III of in . Magnification ×4000; scale bar = 2 µm. Asterisks = islet amyloid; C= capillary; hIAPP = human islet amyloid polypeptide; ISG = insulin secretory granule; K = 1000; M = mitochondria; RBC = red blood cell.

Article Snippet: The human islet amyloid polypeptide (HIP) rat model was created by the transfection of Sprague–Dawley rat with the human islet amyloid polypeptide (hIAPP)-amylin gene in 2004 and initially studied by Butler AE et al. [ ].

Techniques: Control

Journal: Cells

Article Title: An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

doi: 10.3390/cells9112475

Figure Lengend Snippet: The 4- and 8-month-old HIP rat. (Panels ( A , B )) from the 4-month-old HIP rat models. Panel ( A ) illustrates endoplasmic reticulum (ER) stress with prominent widening of the ER in β-cells (yellow arrow) and also note the islet amyloid (asterisk) in left lower region. Panel ( B ) depicts a single β-cell embedded and totally isolated by islet amyloid/human islet amyloid polypeptide (hIAPP) amyloidosis in 4-month-old HIP rat models. Panels C and D are from the 8-month-old HIP rat model. (Panel ( C )) displays the marked decrease in β-cells, which are atrophic and represent changes of apoptosis. Note the islet capillary with its red blood cell (RBC) and its close association with an atrophic apoptotic β-cell with apoptotic bodies and loss of insulin secretory granules (black arrow). (Panel ( D )) depicts an apoptotic β-cell from boxed in area in panel ( C ) and note the apoptotic bodies (arrowheads), loss of cytoplasmic organelles (O) and cytoplasmic vacuoles (apoptotic bodies) along with its nucleus (N) depicting chromatin condensation (C). β = β-cell; K = 1000; N = nucleus; O = cytoplasmic organelle; RBC = red blood cell.

Article Snippet: The human islet amyloid polypeptide (HIP) rat model was created by the transfection of Sprague–Dawley rat with the human islet amyloid polypeptide (hIAPP)-amylin gene in 2004 and initially studied by Butler AE et al. [ ].

Techniques: Isolation

Journal: Cells

Article Title: An Immediate and Long-Term Complication of COVID-19 May Be Type 2 Diabetes Mellitus: The Central Role of β-Cell Dysfunction, Apoptosis and Exploration of Possible Mechanisms

doi: 10.3390/cells9112475

Figure Lengend Snippet: Pancreatic islet β-cell apoptosis in the HIP rat model of T2DM. This representative pseudo-colorized pancreatic islet β-cell in the preclinical 8-month-old HIP rat diabetic model ( D) depicts apoptosis characterized by β-cell atrophy, nuclear chromatin condensation (Cc with white arrows), loss of cytoplasmic organelles (CO), cytoplasmic vacuole formation and apoptotic bodies (arrowheads). Note how islet amyloid may insert into β-cells (arrows and asterisks). β-cell apoptosis in MetS, T2DM and COVID-19 may be due to a combination of a virus virion storm (SARS-CoV-2), redox storm and cytokine storm as they converge and interact with the multiple metabolic toxicities of MetS and prediabetes or overt T2DM, which may result in injury and a response to the injury wound healing mechanism within the islet and its microcirculation and encourage the acceleration of T2DM due to early dysfunction and later loss of β-cells via apoptosis. Nucleus (blue); cytoplasm (red); apoptotic bodies (yellow); extracellular matrix—hashtag islet amyloid (concrete grey color). CO = cytoplasmic organelles; hashtag = islet amyloid; hIAAP = human islet amyloid polypeptide; ISG = electron dense insulin secretory granules (open arrow and encircled by yellow lines of both immature haloed and more mature unhaloed ISG).

Article Snippet: The human islet amyloid polypeptide (HIP) rat model was created by the transfection of Sprague–Dawley rat with the human islet amyloid polypeptide (hIAPP)-amylin gene in 2004 and initially studied by Butler AE et al. [ ].

Techniques: Virus