Disturbed Fatty Acid Oxidation, Endoplasmic Reticulum Stress, and Apoptosis in Left Ventricle of Patients With Type 2 Diabetes.

Chronic heart failure is a common complication in patients with type 2 diabetes mellitus (T2DM). T2DM is associated with disturbed metabolism of fat, which can result in excessive accumulation of lipids in cardiac muscle. In the current study, we assessed mitochondrial oxidation of carbohydrates and fatty acids, lipid accumulation, endoplasmic reticulum (ER) stress, and apoptosis in diabetic left ventricle. Left ventricular myocardium from 37 patients (a group of patients with diabetes and a group of patients without diabetes [ejection fraction >50%]) undergoing coronary artery bypass graft surgery was obtained by subepicardial needle biopsy. The group with diabetes had a significantly decreased rate of mitochondrial respiration fueled by palmitoyl-carnitine that correlated with blood glucose dysregulation, while there was no difference in oxidation of pyruvate. Diabetic myocardium also had significantly decreased activity of hydroxyacyl-CoA dehydrogenase (HADHA) and accumulated more lipid droplets and ceramide. Also, markers of ER stress response (GRP78 and CHOP) and apoptosis (cleaved caspase-3) were elevated in diabetic myocardium. These results show that, even in the absence of contractile failure, diabetic heart exhibits a decreased mitochondrial capacity for ß-oxidation, increased accumulation of intracellular lipids, ER stress, and greater degree of apoptosis. Lower efficiency of mitochondrial fatty acid oxidation may represent a potential target in combating negative effects of diabetes on the heart.

Expression of Leukocytes Following Myocardial Infarction in Rats is Modulated by Moderate White Wine Consumption.

How moderate white wine consumption modulates inflammatory cells infiltration of the ischemic myocardium following permanent coronary ligation was the key question addressed in this study. Male Sprague-Dawley rats were given either a combination of different white wines or water only for 28 days. Three peri-infarct/border zones and a control/nonischemic zone were analysed to determine the expression of myeloperoxidase (MPO) and cluster of differentiation 68 (CD68). Smaller expressions for both MPO and CD68 were found in all three peri-infarct zones of wine drinking animals (p < 0.001). There was no difference in the expression of leukocyte markers between animals drinking standard and polyphenol-rich white wine, although for CD68, a nonsignificant attenuation was noticed. In sham animals, a subepicardial MPO/CD68 immunoreactive "inflammatory ring" is described. Standard white wine consumption caused attenuation of the expression of MPO but not of CD68 in these animals. We conclude that white wine consumption positively modulates peri-infarct inflammatory infiltration.

The Medical School of the Catholic University of Croatia: Principles, Goals, Standards and Organization.

The aim of the study was to present the concept on which the School of Medicine at the Catholic University of Croatia (CUC) will be established. The new School will alleviate the shortage of physicians in Croatia and introduce an innovative form of medical education focused on principles of patient-centered care and social accountability. At the same time, the students will acquire all relevant competencies and levels of knowledge, skills and attitudes that are required by current evidence in medical education, European standards and guidelines for quality assurance at higher education institutions. The four pillars of the CUC Medical School are: 1) distributed medical education that involves health institutions outside major medical centers, 2) the concept of transformative learning, 3) teaching and practicing evidence-based medicine, and 4) implementation of quality management principles supported by information technology solutions for effective management of learning, research and practice. The overall aim of the CUC School of Medicine is to educate and train physicians capable of using best available medical evidence to deliver economically sustainable healthcare that can improve equity and health outcomes in the communities they serve, particularly those that are currently underserved. CONCLUSION: The proposed programme is introducing an original system of modern medical education that insists on developing humanistic aspects of medicine, patient-centred care and social accountability, while maintaining all competencies and knowledge levels that a physician should have according to the current understanding of medical education.

Expression of adhesion molecules on granulocytes and monocytes following myocardial infarction in rats drinking white wine.

Neutrophils and monocytes through their CD15s, CD11b and CD44 adhesion molecules are implicated in the initiation and resolution of cardiac inflammation as well as in healing processes after the myocardial infarction (MI). The aim of this study was to determine the effect of white wine consumption on granulocyte and monocyte CD15s, CD11b, and CD44 expression 24h after the surgically inflicted MI. Granulocytes and monocytes were analyzed by flow cytometry, using whole blood of male Sprague-Dawley rats that consumed white wine for 4 weeks. This group was compared with water only drinking controls, sham animals (subject to surgery without myocardial infarction) and baseline group (intact animals that received no intervention prior to being sacrificed). Sham animals did not differ from baseline animals in CD11b+CD44+ percentage and CD44+ median fluorescence intensity. Wine drinking was associated with striking increase in CD44 expression on monocyte subpopulations. Its expression was three and fourfold increased on monocytes and large monocytes, respectively, relative to the water only drinking controls. Because of known role of CD44 on suppression of post-infarction inflammation, its upregulation on granulocytes and monocytes may significantly contribute to the microenvironment favourable for the cardiac regeneration.

Effects of White Wine Consumption on Weight in Rats: Do Polyphenols Matter?

INTRODUCTION: Effects of white wine and the role of wine polyphenols on weight gain in rats of different age were examined in the 4-week-voluntary-consumption trial. METHODS AND MATERIALS: Biochemically characterized standard (low polyphenols, W) and macerated (high polyphenolic content, PW) white wines were compared. One- and three-month-old Sprague-Dawley male rats (n = 78) were used. Each age group was subdivided into water-only-drinking controls (C), W, and PW-drinking animals. Daily wine and total liquid consumption, food intake, and body weight were measured, and energy intake and feed efficiency index were calculated. RESULTS: In both age categories, wine-drinking animals consumed less food and gained less weight in comparison to C (181 ± 2, 179 ± 6, and 201 ± 5 in younger animals and 32 ± 5, 28 ± 6, and 47 ± 4 grams in older animals, resp.), regardless of wine type. Total energy intake was the lowest in PW-drinking animals. CONCLUSION: Wine-drinking animals gained less weight in comparison to C, regardless of the wines' polyphenol content. Although our results are indicative of the major role of nonphenolic constituents of the wines (probably ethanol), the modifying role of wine phenolics on weight gain cannot be excluded as the group consuming PW had lower total energy intake than other groups.

White Wine Consumption Influences Inflammatory Phase of Repair After Myocardial Infarction in Rats.

Effects of white wine (WW) consumption on the expression of inflammatory markers/mediators (MMP-2, MMP-9, NF-ĸB p65 and TGF-ß1) in myocardial tissue after experimentally induced permanent myocardial ischemia was investigated. Male Sprague-Dawley rats were given either a combination of WW and water or only water, for 28 days. After coronary ligation, animals were left to survive for 24 hours. Three representative areas: infarct/ischemic, peri-infarct/border zone, and control/non-ischemic zones were analyzed for expression of immunoreactivity by measuring the threshold area % of signal density. For MMP-9, significantly smaller expression was found in all 3 zones of wine drinking animals (P < 0.001). There was no difference in MMP-2 immunoreactivity between the 2 groups, except in peri-infarct zones, where the signal was significantly decreased (P < 0.001). The same pattern of expression was found for the NF-κB p65 signal, although no differences between experimental groups were observed for TGF-ß1. White wine consumption decreases the expression of the 3 investigated inflammatory markers/mediators in the peri-infarct zone, suggesting its significant modulatory effect. For MMP-9 and MMP-2, expression was similar to the effect of postischemic reperfusion. No effect on TGF-ß1 was observed, highlighting its role in being the master-switch, changing from the inflammatory to the proliferative stage of infarct healing.

The business process management software for successful quality management and organization: A case study from the University of Split School of Medicine.

OBJECTIVE: Our aim was to describe a comprehensive model of internal quality management (QM) at a medical school founded on the business process analysis (BPA) software tool. METHODS: BPA software tool was used as the core element for description of all working processes in our medical school, and subsequently the system served as the comprehensive model of internal QM. RESULTS: The quality management system at the University of Split School of Medicine included the documentation and analysis of all business processes within the School. The analysis revealed 80 weak points related to one or several business processes. CONCLUSION: A precise analysis of medical school business processes allows identification of unfinished, unclear and inadequate points in these processes, and subsequently the respective improvements and increase of the QM level and ultimately a rationalization of the institution's work. Our approach offers a potential reference model for development of common QM framework allowing a continuous quality control, i.e. the adjustments and adaptation to contemporary educational needs of medical students.

Management of teaching processes using the Share point platform: A case study from the University of Split School of Medicine.

OBJECTIVE: To develop a software tool that will combine teaching timetables with the generation of reports on teaching load. METHODS: The University of Split School of Medicine project team and the external experts from the company LAMA, LLC. determined necessary functionalities and developed the software platform as an extension of the existing software solutions already in use by the Croatian academic community. RESULTS: By combining comprehensive scheduling functionality with planned and performed teaching activities we determined the teaching load and realized automatic generation of payments for adjunct lecturers. The implementation required perfecting of the human resources services, brought about a manifold alleviation of the work of the entire school's administration and substantially increased the effectiveness of the quality management. The software is currently managing 54,676 teaching hours, 841 teaching staff member, 111 teaching rooms, 8 study programs, and 645 courses. CONCLUSION: The program resolved several administrative problems of the school and is an example of successful implementation of IT technology in medical school management.

Expression pattern of CYP24 in liver during ageing in long-term diabetes.

Association of liver calcitriol (active vitamin D metabolite) catabolism with osteomalacia during prolonged use of certain drugs was reported in several recent studies. To examine whether the increased calcitriol catabolism could be a potential link between ageing/diabetes mellitus (DM) and bone loss, we studied the dynamic of expression of CYP24, the main calcitriol catabolising enzyme in the liver of rats during ageing and a long-term experimental DM1. DM1 model was induced with intraperitoneally injected streptozotocin (STZ) (55mg/kg). Sprague-Dawley rats were sacrificed 6 and 12 months after the DM1 induction. The immunohistochemical analyses of CYP24 and transforming growth factor ß 1 (TGF-ß1) expression in the liver were performed. We found that ageing and long-term DM1 resulted in a significantly increased expression of CYP24 in hepatocytes, as well as in non-hepatocyte liver cells (Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells). Ageing and long-term DM1 resulted in an increased expression of TGF-ß1 as well. Expression of CYP24 coexisted with the expression of TGF-ß1 in all types of hepatic cells. We concluded that liver has the capacity for an active vitamin D catabolism in different populations of liver cells, especially in sinusoidal endothelial cells, through an expression of CYP24. That capacity is substantially increased during ageing and long-term diabetes mellitus. Increased liver calcitriol catabolism could be one of the mechanisms of the bone metabolism impairment related to ageing and diabetes.

Aging and a long-term diabetes mellitus increase expression of 1 α-hydroxylase and vitamin D receptors in the rat liver.

Diabetes mellitus (DM) is a metabolic disorder associated with serious liver complications. As a metabolic chronic disease, DM is very common in the elderly. Recent studies suggest ameliorating effects of vitamin D on metabolic and oxidative stress in the liver tissue in an experimental model of DM. The aim of this study was to investigate the expression of vitamin D receptors (VDRs) and 1α-hydroxylase, the key enzyme for the production of active vitamin D form (calcitriol) in the liver during long-term diabetes mellitus type 1 (DM1) in aging rats. We performed immunohistochemical analysis of liver expression of 1α-hydroxylase and VDRs during aging in long-term streptozotocin-induced DM1. 1α-Hydroxylase was identified in the monocyte/macrophage system of the liver. In addition to the nuclear expression, we also observed the expression of VDR in membranes of lipid droplets within hepatocytes. Aging and long-term DM1 resulted in significant increases in the number of 1α-hydroxylase immunoreactive cells, as well as the percentage of strongly positive VDR hepatocytes. In conclusion, the liver has the capacity for active vitamin D synthesis in its monocyte/macrophage system that is substantially increased in aging and long-term diabetes mellitus. These conditions are also characterized by significant increases in vitamin D receptor expression in hepatocytes. The present study suggests that VDR signaling system could be a potential target in prevention of liver complications caused by diabetes and aging.

Diabetes mellitus affects activity of calcium/calmodulin-dependent protein kinase II alpha in rat trigeminal ganglia.

The activity of calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα) may play a critical role in the modulation of nociceptor activity and plasticity of primary sensory trigeminal neurons. The aim of this study was to investigate the immunoreactivity of phosphorylated CaMKIIα (pCaMKIIα) in subpopulations of trigeminal ganglion (TG) neurons in rat models of early diabetes type 1 (dm1) and 2 (dm2). DM1 model was induced with intraperitoneally (i.p.) injected streptozotocin (STZ) (55mg/kg). DM2 rats were fed with the high fat diet (HFD) for 2 weeks and then received 35mg/kg of STZ i.p. Two weeks and 2 months after the STZ-diabetes induction, rats were sacrificed and immunohistochemical analysis for detection of pCaMKIIα immunoreactivity and double immunofluorescence labelling with isolectin (IB4) was performed. Increased intensity of pCaMKIIα immunofluorescence, restricted to IB4-negative small-diameter neurons, was seen in TG neurons two months after STZ-DM1 induction. DM1 model, as well as the obesity (control dm2 groups) resulted in neuronal impaired growth while dm2 model led to neuron hypertrophy in TG. Observed changes may play a critical role in the modulation of nociceptor activity and plasticity of primary sensory trigeminal neurons. In future, innovative strategies for modulation of CaMKIIα activity in specific subpopulations of neurons could be a novel approach in therapy of diabetic trigeminal neuropathy.

Effects of isoflurane postconditioning on chronic phase of ischemia-reperfusion heart injury in rats.

INTRODUCTION: The application of isoflurane in a postconditioning manner, during early reperfusion of ischemic myocardium, reduces the infarct size. Its favorable effect on highly vascularized granulation tissue formation is very important considering the fact that increased genesis of blood vessels in peri-infarct zone reduces the infarct size and improves cardiac function. Taking into consideration the influence of isoflurane on the subacute phase of infarct healing, by using different immunohistochemical markers, we wanted to explore whether isoflurane postconditioning influences the chronic phase of healing. METHODS: The size of infarcted region was measured, and comparisons between isoflurane-treated and control animals were made. Quality of infarcted area was assessed by detecting vascular endothelial growth factor (VEGF), platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) as a marker of angiogenesis, and nestin as a marker of immature progenitor cells, and de novo formed blood vessels (vasculogenesis). RESULTS: There was no difference between the control and isoflurane-treated groups in VEGF and PECAM-1/CD31 expression. However, a large reduction in infarct size was found (68.1% of control). Also, a marked decrease of nestin expression in immature progenitor cells, along with a marked increase of the same marker in cardiomyocytes, (signs of myocardium regeneration), was found in experimental animals when compared to control animals that did not receive isoflurane treatment. CONCLUSIONS: Based on our results, we can emphasize two morphologically detectable benefits of isoflurane postconditioning: a marked reduction in infarct size along with a more mature-looking infarct area in the chronic phase of infarct healing.

Expression of nestin in superior cervical ganglia of rats is influenced by gender and gonadectomy.

Neurons and glia arise from neural progenitor cells that express nestin. Although substantial changes in neuronal development were observed during the postnatal period, data concerning dynamics of nestin expression in the superior cervical ganglia (SCG) of rat during that period are lacking. It is known that gonadectomy and steroid hormones influence the development of neurons in the SCG during the postnatal period, but there are no data on how they influence the persistence of nestin expression in the SCG cells. The dynamics of nestin expression in the SCG in rats of three age groups, as well as the influence of gender and gonadectomy, was investigated. Three groups of male rats were sacrificed at 2, 3 and 6 months of age. Additional groups of male and female Sprague-Dawley rats were gonadectomized at the age of 2 months. After 30 days, they were sacrificed and SCGs were harvested and processed immunohistochemically. Immunoreactivity for nestin in the SCG was observed in satellite glia, based on their expression of s100. The proportion of neurons that were encircled with nestin-immunoreactive satellite cells (nestin encircled neurons, NEN) decreased between second and third month of age (p<0.05). The proportion of NEN was greater in the NPY+ than in the NPY- subpopulation. The proportion of NEN in the SCG of female rats was significantly higher (p<0.05) than that of both, the male rats and ovariectomised groups. The percentage of these neurons was significantly higher (p<0.05) in orchidectomised, in comparison to male rats. Results show the existence of nestin-immunoreactive satellite cells in the SCG of adult rats. A substantial decrease of nestin expression in SCG cells of rats, after the onset of sexual maturation, was observed. This decrease showed significant sex-dependence and was dramatically influenced by gonadal activity.

Expression of PTHrP and PTH/PTHrP receptor 1 in the superior cervical ganglia of rats.

PTHrP and its receptor PTHR1 are found in the CNS and peripheral nervous system. The presence of PTHrP mRNA has been detected in the superior cervical ganglion (SCG), but there are no data on the cellular distribution of PTHrP and PTHR1 in the SCG. Although it is known that ovarian activity and reproductive status influence sympathetic activity, and the PTHrP/PTHR1 system is influenced by estrogens in different tissues, it is not known whether these factors have a similar effect on expression of PTHrP and PTHR1 in the nervous system. Hence, we investigated the presence and distribution of PTHrP and PTHR1 in neurons and glia of the SCG of rats, as well as the influence of ovariectomy on their expression, by using immunohistochemistry. PTHrP and PTHR1 immunoreactivity was observed in cytoplasm as well as in nuclei of almost all neurons in the SCG. In male rats, intensity of PTHrP fluorescence was significantly higher in cytoplasm of NPY-, in comparison to NPY+ neurons (p < 0.05). In female rats, 2 months post-ovariectomy, significantly lower intensity of PTHrP fluorescence in cytoplasm of the SCG neurons was observed in comparison to sham operated animals (p < 0.05). In addition to neurons, PTHrP and PTHR1 immunoreactivity was observed in most of the glia and was not influenced by ovariectomy. Results show the expression of PTHrP and its receptor, PTHR1, in the majority of neurons and glial cells in the SCG of rats. Expression of PTHrP, but not PTHR1 in the cytoplasm of SCG neurons is influenced by ovarian activity.

Behavioral changes following experimentally-induced acute myocardial infarction in rats.

Rats with experimentally-induced acute myocardial infarction (AMI) have proven to be a clinically relevant model for visceral pain. As there are no behavioral data available on rats in the postinfarction period, we aimed to identify specific pain-related behavioral changes following AMI to increase the validity of the model. AMI was induced by left coronary artery ligation and pain-related behavior was analyzed using the open field test (OFT) and elevated plus maze (EPM). Morphine was applied following AMI induction to differentiate pain-related changes from those related to nonspecific global changes in responsiveness. AMI was histologically confirmed. Hypolocomotion was consistently evident in all behavioral tests for both the infarcted group and sham group. In the OFT, both AMI and sham rats exhibited less exploratory behavior and less activity. A similar pattern of behavior was observed in EPM, where both surgical groups showed fewer entries to the open arms and spent less time in the open arms. The sham group with an intact pericardium showed the same pattern of activity as control rats. The reduction in activity and rearing observed following AMI was successfully reversed following morphine injection. This effect was abolished after naloxone application allowing us to attribute observed changes specifically to pain.This study demonstrates that pain-related behavior in the acute postinfarction period is generally characterized by reduced mobility and explorative behavior. Our results showed that cardiac ischemia as a consequence of experimentally-induced infarction is a less important source of pain behavior than manipulation of the pericardium.

Gender and gonadectomy influence on neurons in superior cervical ganglia of sexually mature rats.

Gonadal hormones have a significant influence on both the number of neurons and the density of synapses in the superior cervical ganglion (SCG) during the early postnatal period. There are no studies reporting influence of the absence of these factors in sexually mature animals, although changes in SCG-neurons of the rat were observed up to 6 months of age. Hence, we investigated whether gonadectomy of sexually mature rats influences morphological properties of neurons in the SCG of the rat and if so, would it have a specific effect on neurochemically distinct subpopulations. Male and female Sprague-Dawley rats were gonadectomized at the age of two months. After 30 days, they were sacrificed and SCGs were harvested and processed immunohistochemically. The mean diameter of NPY- neurons was greater in male rats, in comparison to all other groups (p<0.05). The number of NPY+, NPY- and total neurons per section area was significantly higher in female than in male, orchidectomized or the ovariectomized animals (p<0.05). The share of the different neuronal populations in the SCG that were encircled with calretinin-positive baskets (c.b+) or c.b.- (NPY+ or NPY-) was significantly influenced by the gender of the animals and gonadectomy, with significantly more c.b.+ in male animals (p<0.05). Results of the present study indicate that substantial changes in the SCG neurons of the rat occur after reaching sexual maturity, and are influenced by the gonadectomy.

Isoflurane post-conditioning stimulates the proliferative phase of myocardial recovery in an ischemia-reperfusion model of heart injury in rats.

The application of isoflurane in a post-conditioning manner, during early reperfusion following a period of coronary occlusion, has numerous beneficial effects on the ischemic myocardium, including reduction of infarct size. It does so by stimulating a sequence of well studied anti-apoptotic pro-survival mechanisms in a similar manner to various 'ischemic' pre-/post-conditioning approaches which achieve their cardio protective effects in both laboratory and clinical situations. Proliferation of newly formed blood vessels, resulting in formation of highly vascularized granulation tissue, is an essential stage of infarct healing. It can be evaluated by detecting various angiogenic factors, including vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) or by quantification of expression of vascular smooth muscle progenitors, such as Nestin. Expression of these three markers was used to evaluate the effect of early isoflurane post-conditioning in ischemia-reperfusion type cardiac injury. A large reduction in infarct size (59.3% of control), and marked increase of expression of VEGF (43.4%), PECAM-1/CD31 (136%) and Nestin (77.9%) was found in experimental animals when compared to control animals that did not receive isoflurane treatment. Hence, based on our results, we can emphasize two morphologically detectable benefits of isoflurane post-conditioning: a marked reduction in infarct size and much better organization/vascularization of necrotic tissue.

Changes in cardiac innervation during maturation in long-term diabetes.

Diabetic autonomic neuropathy being a common complication of diabetes mellitus (DM) is related to an increased risk of cardiovascular mortality. However, mechanisms underlying changes of innervation density in affected hearts remain insufficiently understood. Hence, the aim of this study was to describe quantitative changes of intra-myocardial nerve terminals in hearts of diabetic rats of various ages. Male Sprague-Dawley rats were injected with 55mg/kg streptozotocin (STZ) (DM group) or with citrate buffer (control). After 2weeks, 2months, 6months and 12months, sections of their hearts were analyzed in five areas-left ventricle, interventricular septum, right ventricle, anterior and posterior wall. Nerve fibers were visualized immunohistochemically, using antibody against a general neuronal marker, protein gene product 9.5 (PGP 9.5). Significant increase in total nerve fibers from all heart areas was observed 2weeks and 2months after diabetes induction, followed by a decrease at 6months and again increase at 12months was observed in both control and diabetic rats. Significant difference between control and diabetic rats was visible after 2weeks and 2months, with diabetic rats exhibiting significantly more nerve fibers. There were no consistent differences in quantity of nerve fibers in different areas of the heart within a particular age-related group of animals. In conclusion, cardiac innervation undergoes dynamic changes both in control and in diabetic rats, with a time-dependent significant increase in neuronal fiber density in diabetic animals. This novel information may contribute to our understanding of pathophysiological changes associated with diabetic cardiac neuropathy.

Increased vitamin D receptor expression in dorsal root ganglia neurons of diabetic rats.

The effects of vitamin D on the nervous system have been studied extensively. In spite of accumulating data about the substantial changes in the vitamin D receptor (VDR) signaling system, during different types of neuroinflammatory diseases, its role in diabetic neuropathy has not been investigated in detail. To assess the role of VDR signaling in diabetic neuropathy, we examined expression of VDRs in dorsal root ganglia (DRG) neurons in a rat model of streptozotocin-induced diabetes mellitus type 1. Diabetes mellitus (DM) type 1 was induced with streptozotocin in male Sprague-Dawley rats. After two months, expression of VDRs was analyzed immunohistochemically in the cytoplasm of L4 and L5 DRG neurons of diabetic rats. Semi-quantitative analysis for the determination of staining in nuclei and plasma-membranes of DRG neurons was performed. A significant increase in VDR expression was observed in DRG neurons of diabetic rats. Expression of VDRs was increased in the cytoplasm, nuclei and in cell membranes of neurons. An increase in VDR expression occurred in all neurons, but the greatest increase of fluorescence intensity in cytoplasm was observed in neurons of small diameter. Results of the present study indicate that the VDR signaling system could be a potential therapeutic target for diabetic neuropathy.

Age-related changes of neurochemically different subpopulations of cardiac spinal afferent neurons in rats.

This study investigated the effect of aging on cardiac spinal afferent neurons in the rat. A patch loaded with retrograde tracer Fast Blue (FB) was applied to all chambers of the rat heart. Morphological and neurochemical characteristics of labeled cardiac spinal afferent neurons were assessed in young (2 months) and old (2 years) rats using markers for likely unmyelinated (isolectin B4; IB4) and myelinated (neurofilament 200; N52) neurons. The number of cardiac spinal afferent neurons decreased in senescence to 15% of that found in young rats (1604 vs. 248). The size of neuronal soma as well as proportion of IB4+ neurons increased significantly, whereas the proportion of N52+ neurons decreased significantly in senescence. Unlike somatic spinal afferents, neurochemically different populations of cardiac spinal afferent neurons experience morphological and neurochemical changes related to aging. A major decrease in total number of cardiac spinal afferent neurons occurs in senescence. The proportion of N52+ neurons decreased in senescence, but it seems that nociceptive innervation is preserved due to increased proportion and size of IB4+ unmyelinated neurons.