Conscious Animals Research Articles

Effects of acute stress, general anesthetics, tonometry, and temperature on intraocular pressure in rats

Intraocular pressure (IOP) is important for eye health as abnormal levels can led to ocular tissue damage. IOP is typically estimated by tonometry, which only provides snapshots of pressure history. Tonometry also requires subject cooperation and corneal contact that may influence IOP readings. The aim of this research was to investigate IOP dynamics of conscious animals in response to stressors, common anesthetics, tonometry, and temperature manipulations. An eye of male Brown-Norway rats was implanted with a fluid-filled cannula connected to a wireless telemetry system that records IOP continuously. Stress effects were examined by restricting animal movements. Anesthetic effects were examined by varying isoflurane concentration or injecting a bolus of ketamine. Tonometry effects were examined using applanation and rebound tonometers. Temperature effects were examined by exposing anesthetized and conscious animals to warm or cool surfaces. Telemetry recordings revealed that IOP fluctuates spontaneously by several mmHg, even in idle and anesthetized animals. Environmental disturbances also caused transient IOP fluctuations that were synchronous in recorded animals and could last over a half hour. Animal immobilization produced a rapid sustained elevation of IOP that was blocked by anesthetics, whereas little-to-no IOP change was detected in isoflurane- or ketamine-anesthetized animals if body temperature (BT) was maintained. IOP and BT decreased precipitously when heat support was not provided and were highly correlated during surface temperature manipulations. Surface temperature had no impact on IOP of conscious animals. IOP increased slightly during applanation tonometry but not rebound tonometry. The results show that IOP is dynamically modulated by internal and external factors that can activate rapidly and last long beyond the initiating event. Wireless telemetry indicates that animal interaction induces startle and stress responses that raise IOP. Anesthesia blocks these responses, which allows for better tonometry estimates of resting IOP provided that BT is controlled.

Myogenic autoregulation in bone marrow arterioles and in vivo intramedullary pressure in femora of conscious, female Long Evans rats.

The ability to regulate skeletal blood flow is critical for the maintenance of bone. The myogenic response is essential for regulating tissue blood flow. Myogenic responsiveness in bone marrow arterioles has not yet been determined. Furthermore, the literature is disparate regarding intramedullary pressures (IMP) within bone. The purposes of this study were to (1) determine whether bone marrow arterioles have myogenic activity and (2) assess if the autoregulatory zone corresponds with IMP. Also, this study provides detailed methodology on dissecting and isolating bone marrow arterioles for functional assessment. Experiment 1: Femoral shafts of female Long Evans rats were catheterized to assess in vivo IMP. Experiment 2: Bone marrow arterioles from female Long Evans rats were cannulated. Active and passive myogenic responses were determined. In vivo intramedullary pressure averaged 32±3mmHg, intramedullary pulse pressure averaged 5.28±0.03mmHg, and the mean maximal diameter and wall thickness of the bone marrow arterioles were 96±7µm and 18±2µm, respectively. An active myogenic response was observed and differed (p<.001) from the passive curve. Bone marrow arterioles have myogenic responsiveness and the autoregulatory zone corresponded with the range of IMP (15-51mmHg) within the femoral diaphysis of conscious animals.

The World of Animals and Birds: Their Feelings, Thoughts, Consciousness, and Their Language

We have our world, but most people think that we are alone. Are we really alone? Did nature forget to create a whole world for animals and birds like humans or we are just not able to discover their world and their life? Most birds and animals have feelings and thoughts like us, they are able to know their friends are, and who their enemies are. The world of animals and birds is really big and complicated. There are many documented stories for conscious animals. You like birds’ songs right? Well, these beautiful songs are birds’ language, their own way to communicate, understand, and deal with nature. Scientists think that discovering the language of birds, their way of communicating will help a lot in discovering the origins of humans language. They discovered that FOXP2 is the gene that is responsible for language creating, and it’s found in both humans and birds. So, simply, the world is not restricted to humans..!

Molecular and Electrophysiological Role of Diabetes-Associated Circulating Inflammatory Factors in Cardiac Arrhythmia Remodeling in a Metabolic-Induced Model of Type 2 Diabetic Rat.

Background: Diabetic patients have prolonged cardiac repolarization and higher risk of arrhythmia. Besides, diabetes activates the innate immune system, resulting in higher levels of plasmatic cytokines, which are described to prolong ventricular repolarization. Methods: We characterize a metabolic model of type 2 diabetes (T2D) with prolonged cardiac repolarization. Sprague-Dawley rats were fed on a high-fat diet (45% Kcal from fat) for 6 weeks, and a low dose of streptozotozin intraperitoneally injected at week 2. Body weight and fasting blood glucose were measured and electrocardiograms of conscious animals were recorded weekly. Plasmatic lipid profile, insulin, cytokines, and arrhythmia susceptibility were determined at the end of the experimental period. Outward K+ currents and action potentials were recorded in isolated ventricular myocytes by patch-clamp. Results: T2D animals showed insulin resistance, hyperglycemia, and elevated levels of plasma cholesterol, triglycerides, TNFα, and IL-1b. They also developed bradycardia and prolonged QTc-interval duration that resulted in increased susceptibility to severe ventricular tachycardia under cardiac challenge. Action potential duration (APD) was prolonged in control cardiomyocytes incubated 24 h with plasma isolated from diabetic rats. However, adding TNFα and IL-1b receptor blockers to the serum of diabetic animals prevented the increased APD. Conclusions: The elevation of the circulating levels of TNFα and IL-1b are responsible for impaired ventricular repolarization and higher susceptibility to cardiac arrhythmia in our metabolic model of T2D.

Chymase Dependent Pathway of Angiotensin II Generation and Rapeseed Derived Peptides for Antihypertensive Treatment of Spontaneously Hypertensive Rats.

The contribution of chymase, one of the enzymes responsible for angiotensin II generation in non-ACE pathway, remains unclear in the development of hypertension. The aim of the study was to investigate chymase inhibition as potential antihypertensive therapy in spontaneously hypertensive rats (SHR). To block chymase we employed chymostatin, a commercial inhibitor, and new analogues of rapeseed-derived peptides, VWIS and RIY. These simple and easy to obtain peptides not only block chymase, but also possess weak activity to inhibit ACE. This is a first attempt to evaluate the impact of chronic administration of selected inhibitors on blood pressure of SHR in two phases of hypertension. Male SHR (6 or 16 weeks old) were treated daily for two weeks with chymostatin (CH; 2 mg/kg/day), the peptides VWIS (12.5 mg/kg/day) or RIY (7.5 mg/kg/day); control groups received chymostatin solvent (0.15% DMSO in saline) or peptide solvent (saline). The substances were administered intravenously to conscious animals via a chronically cannulated femoral vein. Systolic blood pressure (SBP) was measured by telemetry. Metabolic parameters were measured weekly, and tissue samples were harvested after two weeks of treatment. None of the administered chymase inhibitors affected the development of hypertension in young rats. Only RIY exhibited beneficial properties when administered in the established phase of hypertension: SBP decreased from 165 ± 10 to 157 ± 7 mmHg while the excretion of nitric oxide metabolites increased significantly. The glomerulosclerosis index was lower after RIY treatment in both age groups (significant only in young rats 0.29 ± 0.05 vs 0.48 ± 0.04 in the control group; p < 0.05). Hence, it seems that peptide RIY exhibits some positive effect on renal morphology. The results obtained suggest that the peptide RIY may be a useful tool in the treatment of hypertension, especially in cases when ACE inhibitors are not effective.

The world of animals and birds: Their feelings, thoughts, consciousness, and their language.

We have our world, but most people think that we are alone. Are we really alone? Did nature forget to create a whole world for animals and birds like humans or we are just not able to discover their world and their life? Most birds and animals have feelings and thoughts like us, they are able to know their friends are, and who their enemies are. The world of animals and birds is really big and complicated. There are many documented stories for conscious animals. You like birds’ songs right? Well, these beautiful songs are birds’ language, their own way to communicate, understand, and deal with nature. Scientists think that discovering the language of birds, their way of communicating will help a lot in discovering the origins of humans language. They discovered that FOXP2 is the gene that is responsible for language creating, and it’s found in both humans and birds. So, simply, the world is not restricted to humans..!

Respiratory Modulated Pacing Improves Outcomes in Heart Failure

Heart failure is a leading cause of mortality and morbidity globally. Current cardiac pacemakers pace the heart rate at regular monotonic intervals. However, heart rate is dynamic, with greater heart rate variability (HRV) being a positive prognostic indicator of cardio-vascular health. HRV changes rhythmically with breathing, termed respiratory sinus arrythmia (RSA). This is an evolutionary conserved phenomenon thought to be controlled by the parasympathetic nervous system. RSA is prominent in children and healthy adults but absent in many cardiovascular diseases, including heart failure. We hypothesised that pacing the heart with novel respiratory modulated pacing would improve outcomes in heart failure with reduced ejection fraction compared to conventional monotonic pacing. Heart failure was induced in adult Romney sheep by a microembolisation technique. Eight to ten weeks post embolization sheep were implanted with an arterial pressure probe, diaphragmatic electrodes, aortic flow probe, coronary artery flow probe, a pacing lead on the left atria, and split into three groups. RSA paced (n = 5), monotonically paced (n = 5), and time control (n = 5). One week baseline recording was followed by four weeks of pacing, and one week off-pace, before terminal experiments and tissue collection. All recordings were in conscious animals. Respiratory modulated pacing was generated by a proprietary device (Ceryx medical) which receives input from the diaphragmatic electrodes to pace the heart with real time respiratory modulation. RSA pacing resulted in a significant increase in cardiac output (4 weeks of pacing: Δ RSA: 1.4 ± 0.5, Δ Mono: -1.2 ± 1.0, Δ TC: -0.2 ± 1.2 L/min), and ejection fraction (4 weeks of pacing: ΔRSA: 10.6 ± 9.2, Δ Mono: -4.8 ± 4.5, ΔTC: -3.0 ± 3.4 %) compared to monotonic pacing, with no difference in heart rate between groups. The increase in cardiac output was not associated with a change in MAP, indicating total peripheral resistance was reduced. RSA also caused a significant reduction in apnea incidence, suggesting improvement in respiratory instabilities. Reinstalling RSA may be a novel therapeutic target for improving outcomes in heart failure and opens the possibility of new device-based therapies in other diseases of cardiac inefficiency. We propose that the next generation of pacemakers should incorporate respiratory modulation.

The Influence of Anesthesia on the Cardiovascular Effects of Centrally Administered Clonidine

The α2 adrenergic receptor (α2AR) agonists are known to induce hypotensive responses when administered via intracerebroventricular (icv) route in normotensive rats anesthetized with either pentobarbital or urethane. However, the icv injection of α2AR agonists such as clonidine (CLO) produces hypertensive responses in normotensive conscious rats. To date, the effects icv administration of CLO in normotensive rats under ketamine/xylazine anesthesia, a commonly used anesthetic combination in experimental studies, is still unknown. We hypothesized that anesthetic drugs differentially modulate cardiovascular responses to centrally administered CLO. To evaluate this hypothesis, we assessed blood pressure (BP) and heart rate (HR) of normotensive male rats anesthetized with pentobarbital or ketamine/xylazine, both under mechanical ventilation. These animals received CLO (10 μg/5 μL) or dexmedetomidine (DEX; 0.6 μg/5 μL) by icv route. In additional experiments, yohimbine (5 μg/5 μL), a selective α2AR antagonist, was given by icv route 15 min before a second injection of CLO or DEX in ketamine/xylazine anesthetized rats. As widely described, the icv microinjection of CLO decreased the mean arterial pressure (MAP) and HR by 40.73 ± 6.3 mmHg and 134 ± 15 bpm in pentobarbital anesthetized rats (n = 5). On the other hand, in ketamine/xylazine anesthetized rats (n = 6) CLO increased MAP by 29.4 ± 5.1 mmHg and decreased HR by 34 ± 5 bpm, a less pronounced effect when compared with the pentobarbital group (p < 0.0001). Similarly, the icv microinjection of DEX in ketamine/xylazine anesthetized rats (n = 6) increased MAP by 20.8 ± 3.2 mmHg and decreased HR by 51 ± 16 bpm. Notably, yohimbine generated a pattern of hypotensive responses comparable to CLO and DEX. Additionally, after yohimbine administration, both CLO- and DEX-increased MAP were reduced to 9.9 ± 2.3 mmHg and 6.7 ± 1.1 mmHg, respectively (n = 6, p < 0.05), despite the lack of influence of yohimbine in the bradycardia induced by these α2AR agonists in ketamine/xylazine anesthetized rats. This study discloses that in normotensive rats under ketamine/xylazine anesthesia, central administration of CLO produces a hypertensive effect, opposing the findings obtained in pentobarbital-anesthetized rats and resembling the vascular responses described in conscious animals. This data was reproduced by DEX and reduced by yohimbine, suggesting that stimulation of central α2AR takes a preponderant role in this effect. Our results reinforce the relevance regarding the influence of anesthetic choice for studies involving cardiovascular parameters.

Which QT Correction Method is Most Consistent?

An important aspect of the drug development is the preclinical determination of the effect a drug candidate has on the ECG QT-interval. The QT-interval is the period between the start of the Q-wave and end of the T-wave. This represents the time from the start of ventricular depolarization to the end of ventricular repolarization. A prolonged QT-interval is linked to the arrhythmia risk Torsade de Pointes and is used as a biomarker in preclinical safety pharmacology studies. Determining a compound's arrhythmia risk based on QT-interval prolongation is insufficient as the drug effect can be obscured by the physiological inverse relationship between heart rate and QT-interval. To better elucidate the drug-induced effect on QT-interval, it is standard practice to correct the QT-interval for changes in heart rate. The majority of safety pharmacology studies use telemetry techniques in conscious ambulatory animals. In these studies, a wide range of heart rates occur and correction methods are required regardless of test drug effects on heart rate. Many correction methods have been designed to account for the heart rate effect on QT. Adequacy of QT correction is dependent on the correction method, the species, sex, age, and even on environmental conditions. Historically fixed population QT correction methods are used, such as Bazett's and Fridericia's which rely on set formulas with effectiveness that varies by species. Individual animal correction methods are gaining popularity and are theoretically better to deal with variations in the individual relationship between heart rate and QT-interval. We aim to identify which correction methods are most broadly applicable and introduce the least variability in the corrected QT values. We hypothesize that an individual correction method, that accounts for multiple variables that affect the RR/QT relationship will be the most consistent across individuals, days, and species. To test this hypothesis, we utilized baseline data collected during numerous safety pharmacology assessments and calculated corrected QT values using various methods. The relationship between the corrected QT and heart rate were then compared. For each ECG recording, the correction method resulting in the lowest correlation between the corrected QT and heart rate was identified. A chi-squared test was used to determine which method was the best at reducing the correlation between heart rate and QT interval. We also determined which method produced the lowest variability in the corrected QT values. To do this, the corrected QT values were averaged for the entire recording for each method, and the resulting variabilities were compared. For each ECG recording, the correction method resulting in the lowest variability was determined and a chi-squared test was applied to determine which is most consistent. In conclusion our results demonstrate that individual correction methods are the most consistent, allowing for more accurate comparisons between subjects, species, and dose groups.

5‐HT1A Receptor Activation by Buspirone Facilitates Post‐Inflammatory Intestinal Hypersensitivity in a Rat Model

Intestinal hypersensitivity is the most common symptom and cause of pain in patients with post-inflammatory irritable bowel syndrome (PI-IBS). Several lines of evidence suggest that central serotonin (5-HT) and its receptors significantly contribute to the phenomenon and therefore may be prospective therapeutic targets for relieving abdominal pain and discomfort in PI-IBS. We demonstrated previously that buspirone, a partial agonist of the 5-HT1A receptors, dose-dependently inhibited visceromotor reactions and medullary neuronal responses to noxious colorectal distension in healthy awake dogs and anesthetized rats, indicating the drug's antinociceptive properties in normal conditions. However, whether the 5-HT1A agonist can be beneficial for post-inflammatory intestinal hypersensitivity and hyperalgesia, which are thought to be associated with altered central 5-HT signaling, is still unknown. In the presented study, the effect of systemic buspirone (Sigma-Aldrich, USA) on intestinal hypersensitivity and its underlying neuronal mechanisms were evaluated in Wistar rats recovered from trinitrobenzene sulfonic acid (TNBS)-induced colitis. To assess gut sensitivity, the electromyography recordings of visceromotor reaction to colorectal distension (CRD) and extracellular microelectrode recordings of CRD-evoked caudal medulla neuronal responses were performed in conscious and urethane-anesthetized animals respectively. The results showed that in intestinal hypersensitive rats the visceromotor reaction and medullary neuronal responses to CRD in 40-60 days after TNBS treatment, despite the absence of obvious gut damage by this time, were increased compared with those in norm. Subcutaneous injection of buspirone (2 mg/kg), which exerted antinociceptive effect in healthy control group, further enhanced visceromotor reaction to CRD in post-colitis animals. In neurophysiological experiments on intestinal hypersensitivity rats, activation of the 5-HT1A receptors by intravenously administered buspirone (2 and 4 mg/kg) resulted in a dose-dependent increase of the CRD-evoked activity in the majority of the caudal medullary neurons, suggesting that the pro-algesic effect of the drug can at least partially be mediated by its excitatory action at the supraspinal level. These data demonstrate that the 5-HT1A agonist buspirone loses its antinociceptive properties in post-colitis conditions and thus may not be useful for reliving visceral hypersensitivity and hyperalgesia in PI-IBS.

Hypertension due to loss of water

In the current issue of Acta Physiologica, two papers are published investigating the development of arterial hypertension under conditions of pathological loss of free water in two disease models. Kovaric et al 1 studied rats with chronic renal failure, shedding excessive free water via their remnant kidney due to a hypostenuric concentrating defect. Wild et al. 2 investigated a transgenic mouse model for psoriasis, losing free water via the psoriatic skin lesions. In both cases the animals displayed hypertension, cutaneous vasoconstriction, and metabolic adaptations towards enhanced production of urea and organic osmolytes typical for a phylogenetically ancient water conservation response termed aestivation 3 . The international consortia of investigators spearheaded by Titze, Karbach, and Kitada therefore conclude that in both cases the hypertension was due to cutaneous vasoconstriction in an attempt to limit epidermal water loss. Because in either case the hypertension was associated with loss of water, and thus with hypo- rather than hypervolemia, the authors argue, that this concept of pathogenesis of hypertension is antipodal to the classic view that relies on hypervolemia due to sodium retention.

Ritual Slaughter: The Tradition of Pilot Whale Hunting on the Faroe Islands.

Faroese people consider grindadráp, the hunting of pilot whales, as a part of their cultural heritage, but from the point of view of veterinary sciences and biology, the method of killing pilot whales is a form of a ritual slaughter performed on fully conscious animals that are aware of their circumstances. Pilot whales are social, intelligent, and communicative animals that demonstrate complex social behaviors. Therefore, this traditional whaling method should be considered as a procedure in which animals are exposed to high levels of distress. In the context of contemporary civilizational development and material welfare, the practice of whaling may appear to be an inadequate and cruel relic of the past. This text explores social and cultural issues caused by pilot whale hunts and presents an understanding of the term tradition and some perspectives of how traditions change. The specificity of pilot whales as a species is presented, setting a foundation for a discussion about hunting itself. The conclusion of the text discusses different social perceptions of grindadráp by presenting arguments for and against the hunting. This analysis includes a presentation of actions undertaken bywhale hunting opponents.

Developments in Understanding Diffuse Noxious Inhibitory Controls: Pharmacological Evidence from Pre-Clinical Research.

Bulbospinal pathways regulate nociceptive processing, and inhibitory modulation of nociception can be achieved via the activity of diffuse noxious inhibitory controls (DNIC), a unique descending pathway activated upon application of a conditioning stimulus (CS). Numerous studies have investigated the effects of varied pharmacological systems on the expression status of a) DNIC (as measured in anaesthetised animals) and b) the descending control of nociception (DCN), a surrogate measure of DNIC-like effects in conscious animals. However, the complexity of the underlying circuitry that governs initiation of a top-down inhibitory response in reaction to a CS, coupled with the methodological limitations associated with using pharmacological tools for its study, has often obscured the exact role(s) of a given drug. In this literature review, we discuss the pharmacological manipulation interrogation strategies that have hitherto been used to examine the functionality of DNIC and DCN. Discreet administration of a substance in the spinal cord or brain is considered in the context of action on one of four hypothetical systems that underlie the functionality of DNIC/DCN, where interpreting the outcome is often complicated by overlapping qualities. Systemic pharmacological modulation of DNIC/DCN is also discussed despite the fact that the precise location of drug action(s) cannot be pinpointed. Chiefly, modulation of the noradrenergic, serotonergic and opioidergic transmission systems impacts DNIC/DCN in a manner that relates to drug class, route of administration and health/disease state implicated. The advent of increasingly sophisticated interrogation tools will expedite our full understanding of the circuitries that modulate naturally occurring pain-inhibiting pathways.

Modulation of the initial stages of systemic inflammation by intervention in the NFkB signalling pathway

Sepsis is a systemic inflammatory state mediated by the innate immune system resulting in an excessive cellular response to severe infection, with high levels of morbidity and mortality. Furthermore, patients who survive sepsis, have long-term cognitive and functional impairment. Animal models are essential to clarify the pathophysiological mechanisms of sepsis. Herein, we characterise an animal model of lipopolysaccharide (LPS)-induced inflammation, evaluating neural and cardiac function, during the initial stages of infection. Male Wistar rats (12–20 wks, n = 24) were injected with LPS (E. coli serotype O127:B8; tail vein) and divided into 3 groups: LPS6 (6 mg/kg), LPS12 (12 mg/kg) and Sham (NaCl 0.9%; 0.1 ml/100g). At 6 and 24 h after LPS injection, an autonomic evaluation was performed in both conscious animals, with continuous radio-telemetry recording of blood pressure (BP) and heart rate (HR), and in anaesthetised animals (induction: sodium pentobarbital, 60 mg/kg, ip; maintenance: 20% solution, v/v) with BP, ECG, HR, tracheal pressure, respiratory frequency (RF) and body temperature continuously monitored. Baro and chemoreflex were evaluated with phenylephrine (0.2 ml, 25 µg/ml; iv) and lobeline (0.2 ml, 25 μg/ml; iv), respectively. Behavioural changes were also evaluated through the elevated-plus maze, open-field and Y-maze tests. Immunohistochemistry and RT-PCR were executed to determine heart and brain inflammatory state. Serum biomarkers levels for organ disfunction were also measured. Overall our results show a rise in BP and HR, and elevated RF due to increased chemoreflex sensitivity. 24 h following LPS injection, all groups have a significantly decreased baroreflex (p < 0.05), however, 6 h post-injection, LPS12 show a statistically significant increase in baroreceptor reflex (p < 0.05). At both time-points, the two LPS groups present an anxiety-like behaviour, associated with less locomotor/exploratory activity and highly significant cognitive impairment (p < .0001). The autonomic evaluation of the anaesthetised LPS12 group results in an increase of the autonomic tone at 6 h post-LPS followed by a decrease at 24 h. The LPS6 group shows the opposite profile. Interestingly, conscious animals reveal a slightly different profile in both groups, with a continuous increase in autonomic tone for LPS12 and a decrease 24 h post-LPS in LPS6 group. The molecular studies show reactive astrogliosis and microgliosis, due to inflammatory processes in the hippocampus, as well as, an upregulation of pro-inflammatory factors in the heart and brain. Serum analysis yielded higher levels of biomarkers for renal and liver dysfunction (p < .05) and pancreatic and neuromuscular injury (p < .05), in the LPS12 group. Concluding, LPS administration induces strong modifications in both cardiac and neurological systems, during the early stages of the systemic inflammatory response. Being a good model for further pathophysiological and pharmacological studies related to Sepsis.

Pharmacological characterization of MT-1207, a novel multitarget antihypertensive agent.

Hypertension is a serious public health problem worldwide. MT-1207, chemically named 3-(4-(4-(1H-benzotriazole-1-yl)butyl)piperazine-1-yl) benzisothiazole hydrochloride, is a new chemical entity that has entered into clinical trial as antihypertensive agent in China. In this paper we report the pharmacological profile of MT-1207 regarding its acute, subacute, and long-term effects on hypertensive animal models, and its actions on isolated organs in vitro as well as its molecular targets. Blood pressure (BP) was measured in conscious animals; amlodipine was taken as a positive control drug. We showed that both single dose of MT-1207 (1.25-20 mg/kg, ig) in spontaneously hypertensive rats (SHR) and MT-1207 (0.25-6 mg/kg, ig) in two-kidney one-clip (2K1C) dogs dose-dependently decreased BP. MT-1207 quickly decreased BP within 5 min after administration; the hypotensive effect lasted for 8 and 12 h, respectively, in SHR and 2K1C dogs without reflex increase in heart rate. Multiple doses of MT-1207 (5 mg · kg-1 · d-1 in SHR; 2 mg · kg-1 · d-1 in 2K1C dogs, for 7 days) significantly decreased BP, slightly reduced heart rate, and both of them recovered after withdrawal. Long-term administration of MT-1207 (10 mg · kg-1 · d-1 for 4 months or more time) produced a stable BP reduction, improved baroreflex sensitivity, reduced renal and cardiovascular damage in SHR, and delayed stroke occurrence and death in stroke-prone SHR. In isolated rat aortic rings precontracted by adrenaline, KCl, noradrenaline or 5-hydroxytryptamine (5-HT), MT-1207 (10-9-10-4 M) caused concentration-dependent relaxation. In a panel of enzyme activity or radioligand binding assays of 87 molecular targets, MT-1207 potently inhibited adrenergic α1A, α1B, α1D, and 5-HT2A receptors with Ki < 1 nM. The antagonism of MT-1207 against these receptors was confirmed in isolated rabbit arteries. We conclude that MT-1207 is a novel and promising single-molecule multitarget agent for hypertension treatment to reduce hypertensive organ damage and stroke mortality.

A mouse model of endometriosis that displays vaginal, colon, cutaneous, and bladder sensory comorbidities.

Endometriosis is a painful inflammatory disorder affecting ~10% of women of reproductive age. Although chronic pelvic pain (CPP) remains the main symptom of endometriosis patients, adequate treatments for CPP are lacking. Animal models that recapitulate the features and symptoms experienced by women with endometriosis are essential for investigating the etiology of endometriosis, as well as developing new treatments. In this study, we used an autologous mouse model of endometriosis to examine a combination of disease features and symptoms including: a 10week time course of endometriotic lesion development; the chronic inflammatory environment and development of neuroangiogenesis within lesions; sensory hypersensitivity and altered pain responses to vaginal, colon, bladder, and skin stimulation in conscious animals; and spontaneous animal behavior. We found significant increases in lesion size from week 6 posttransplant. Lesions displayed endometrial glands, stroma, and underwent neuroangiogenesis. Additionally, peritoneal fluid of mice with endometriosis contained known inflammatory mediators and angiogenic factors. Compared to Sham, mice with endometriosis displayed: enhanced sensitivity to pain evoked by (i) vaginal and (ii) colorectal distension, (iii) altered bladder function and increased sensitivity to cutaneous (iv) thermal and (v) mechanical stimuli. The development of endometriosis had no effect on spontaneous behavior. This study describes a comprehensive characterization of a mouse model of endometriosis, recapitulating the clinical features and symptoms experienced by women with endometriosis. Moreover, it delivers the groundwork to investigate the etiology of endometriosis and provides a platform for the development of therapeutical interventions to manage endometriosis-associated CPP.

Unlimited associative learning and consciousness: further support and some caveats about a link to stress

Birch, Ginsburg, and Jablonka, in an article in this issue of Biology and Philosophy, provided a much-needed condensation of their well-reasoned theory of Unlimited Associative Learning (UAL). This theory compellingly identifies the conscious animals (vertebrates, arthropods, and cephalopod molluscs) and the time when the evolutionary transition to consciousness was completed (Cambrian Period). The authors convincingly explained their use of UAL as a “transition marker,” identified two more features by which UAL can be recognized, showed how UAL’s learning features relate to consciousness, and how investigating consciousness is analogous to investigating life. My constructive criticisms are that I wish they had taken a stand on which organisms and entities are not conscious, and I feel they made too many predictions by which to test the UAL theory. That is, some of the proposed tests are unnecessary because parts of UAL are already supported by enough evidence, and other proposed tests are so ambitious as to be nearly impossible to complete. Finally, UAL has a major, detailed, sub-hypothesis that says such learning led to stress and to the evolution of mechanisms to cope with this stress; but this idea is speculative and requires the most basic testing to judge whether it could be valid.

Trans-illumination intestine projection imaging of intestinal motility in mice

Functional intestinal imaging holds importance for the diagnosis and evaluation of treatment of gastrointestinal diseases. Currently, preclinical imaging of intestinal motility in animal models is performed either invasively with excised intestines or noninvasively under anesthesia, and cannot reveal intestinal dynamics in the awake condition. Capitalizing on near-infrared optics and a high-absorbing contrast agent, we report the Trans-illumination Intestine Projection (TIP) imaging system for free-moving mice. After a complete system evaluation, we performed in vivo studies, and obtained peristalsis and segmentation motor patterns of free-moving mice. We show the in vivo typical segmentation motor pattern, that was previously shown in ex vivo studies to be controlled by intestinal pacemaker cells. We also show the effects of anesthesia on motor patterns, highlighting the possibility to study the role of the extrinsic nervous system in controlling motor patterns, which requires unanesthetized live animals. Combining with light-field technologies, we further demonstrated 3D imaging of intestine in vivo (3D-TIP). Importantly, the added depth information allows us to extract intestines located away from the abdominal wall, and to quantify intestinal motor patterns along different directions. The TIP system should open up avenues for functional imaging of the GI tract in conscious animals in natural physiological states.

Noninvasive assessment of radiation-induced renal injury in mice

Purpose The kidney is a radiosensitive late-responding normal tissue. Injury is characterized by radiation nephropathy and decline of glomerular filtration rate (GFR). The current study aimed to compare two rapid and cost-effective methodologies of assessing GFR against more conventional biomarker measurements. Methods C57BL/6 mice were treated with bilateral focal X-irradiation (1x14Gy or 5x6Gy). Functional measurements of kidney injury were assessed 20 weeks post-treatment. GFR was estimated using a transcutaneous measurement of fluorescein-isothiocyanate conjugated (FITC)-sinistrin renal excretion and also dynamic contrast-enhanced CT imaging with a contrast agent (ISOVUE-300 Iopamidol). Results Hematoxylin and eosin (H&E) and Periodic acid-Schiff staining identified comparable radiation-induced glomerular atrophy and mesangial matrix accumulation after both radiation schedules, respectively, although the fractionated regimen resulted in less diffuse tubulointerstitial fibrosis. Albumin-to-creatinine ratios (ACR) increased after irradiation (1x14Gy: 100.4 ± 12.2 µg/mg; 6x5Gy: 80.4 ± 3.02 µg/mg) and were double that of nontreated controls (44.9 ± 3.64 µg/mg). GFR defined by both techniques was negatively correlated with BUN, mesangial expansion score, and serum creatinine. The FITC-sinistrin transcutaneous method was more rapid and can be used to assess GFR in conscious animals, dynamic contrast-enhanced CT imaging technique was equally safe and effective. Conclusion This study demonstrated that GFR measured by dynamic contrast-enhanced CT imaging is safe and effective compared to transcutaneous methodology to estimate kidney function.

The ability of baroreflex activation to improve blood pressure and resistance vessel function in spontaneously hypertensive rats is dependent on stimulation parameters.

Baroreflex activation by electric stimulation of the carotid sinus (CS) effectively lowers blood pressure. However, the degree to which differences between stimulation protocols impinge on cardiovascular outcomes has not been defined. To address this, we examined the effects of short- and long-duration (SD and LD) CS stimulation on hemodynamic and vascular function in spontaneously hypertensive rats (SHRs). We fit animals with miniature electrical stimulators coupled to electrodes positioned around the left CS nerve that delivered intermittent 5/25 s ON/OFF (SD) or 20/20 s ON/OFF (LD) square pulses (1 ms, 3 V, 30 Hz) continuously applied for 48 h in conscious animals. A sham-operated control group was also studied. We measured mean arterial pressure (MAP), systolic blood pressure variability (SBPV), heart rate (HR), and heart rate variability (HRV) for 60 min before stimulation, 24 h into the protocol, and 60 min after stimulation had stopped. SD stimulation reversibly lowered MAP and HR during stimulation. LD stimulation evoked a decrease in MAP that was sustained even after stimulation was stopped. Neither SD nor LD had any effect on SBPV or HRV when recorded after stimulation, indicating no adaptation in autonomic activity. Both the contractile response to phenylephrine and the relaxation response to acetylcholine were increased in mesenteric resistance vessels isolated from LD-stimulated rats only. In conclusion, the ability of baroreflex activation to modulate hemodynamics and induce lasting vascular adaptation is critically dependent on the electrical parameters and duration of CS stimulation.