1
|
Roy RK, Yao Y, Green IK, Aitken AV, Biancardi VC, Silver R, Stern JE. Blood flows from the SCN toward the OVLT within a new brain vascular portal pathway. SCIENCE ADVANCES 2024; 10:eadn8350. [PMID: 38905332 PMCID: PMC11192075 DOI: 10.1126/sciadv.adn8350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 05/16/2024] [Indexed: 06/23/2024]
Abstract
The suprachiasmatic nucleus (SCN) sets the phase of oscillation throughout the brain and body. Anatomical evidence reveals a portal system linking the SCN and the organum vasculosum of the lamina terminalis (OVLT), begging the question of the direction of blood flow and the nature of diffusible signals that flow in this specialized vasculature. Using a combination of anatomical and in vivo two-photon imaging approaches, we unequivocally show that blood flows unidirectionally from the SCN to the OVLT, that blood flow rate displays daily oscillations with a higher rate at night than in the day, and that circulating vasopressin can access portal vessels. These findings highlight a previously unknown central nervous system communication pathway, which, like that of the pituitary portal system, could allow neurosecretions to reach nearby target sites in OVLT, avoiding dilution in the systemic blood. In both of these brain portal pathways, the target sites relay signals broadly to both the brain and the rest of the body.
Collapse
|
2
|
Najjar RS, Roy RK, Stern JE, Feresin RG. Raspberry polyphenols target molecular pathways of heart failure. J Nutr Biochem 2024; 124:109535. [PMID: 37984734 DOI: 10.1016/j.jnutbio.2023.109535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 11/03/2023] [Accepted: 11/15/2023] [Indexed: 11/22/2023]
Abstract
Approximately 650,000 new cases of heart failure (HF) are diagnosed annually with a 50% five-year mortality rate. HF is characterized by reduced left ventricular (LV) ejection fraction and hypertrophy of the LV wall. The pathophysiological remodeling of the heart is mediated by increased oxidative stress and inflammation. Raspberries are rich in polyphenols which may favorably impact enzymes involved in redox homeostasis while also targeting inflammatory signaling. Thus, the objective of this study was to investigate whether raspberry polyphenols could attenuate HF. Sprague Dawley rats consumed a 10% (w/w) raspberry diet for 7 weeks. At week 3, HF was surgically induced via coronary artery ligation. Hemodynamics and morphology of the heart were assessed. Expression of cardiac proteins involved in oxidative stress, inflammation, apoptosis, and remodeling were examined, and histological analysis was conducted. Additionally, human cardiomyocytes were treated with raspberry polyphenol extract (RBPE) followed by CoCl2 to chemically induce hypoxia. Redox status, apoptosis, and mitochondrial dysfunction were measured. Raspberries attenuated reductions in cardiac function and reduced morphological changes which coincided with reduced toll-like receptor (TLR)4 signaling. Reductions in oxidative stress, apoptosis, and remodeling occurred in vivo. Incubation of cardiomyocytes with RBPE attenuated CoCl2-induced oxidative stress and apoptosis despite pronounced hypoxia-inducible factor (HIF)-1α expression. These data indicate that consumption of raspberries can reduce the underlying molecular drivers of HF; thus, leading to the observed improvements in cardiac functional capacity and morphology. This dietary strategy may be an effective alternative strategy for treating HF. However, further investigation into alternative models of HF is warranted.
Collapse
|
3
|
Althammer F, Roy RK, Kirchner MK, McGrath S, Lira EC, Stern JE. Angiotensin-II drives changes in microglia-vascular interactions in rats with heart failure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.22.573045. [PMID: 38187537 PMCID: PMC10769361 DOI: 10.1101/2023.12.22.573045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Activation of microglia, the resident immune cells of the central nervous system, leading to the subsequent release of pro-inflammatory cytokines, has been linked to cardiac remodeling, autonomic disbalance, and cognitive deficits in heart failure (HF). While previous studies emphasized the role of hippocampal Angiotensin II (AngII) signaling in HF-induced microglial activation, unanswered mechanistic questions persist. Evidence suggests significant interactions between microglia and local microvasculature, potentially affecting blood-brain barrier integrity and cerebral blood flow regulation. Still, whether the microglial-vascular interface is affected in the brain during HF remains unknow. Using a well-established ischemic HF rat model, we demonstrate increased vessel-associated microglia (VAM) in HF rat hippocampi, which showed heightened expression of AngII AT1a receptors. Acute AngII administration to sham rats induced microglia recruitment to the perivascular space, along with increased expression of TNFa. Conversely, administering an AT1aR blocker to HF rats prevented the recruitment of microglia to the perivascular space, normalizing their levels to those in healthy rats. These results highlight the critical importance of a rather understudied phenomenon (i.e., microglia-vascular interactions in the brain) in the context of the pathophysiology of a highly prevalent cardiovascular disease, and unveil novel potential therapeutic avenues aimed at mitigating neuroinflammation in cardiovascular diseases.
Collapse
|
4
|
Althammer F, Roy RK, Kirchner MK, Lira EC, Schimmer S, Charlet A, Grinevich V, Stern JE. Impaired oxytocin signaling in the central amygdala in rats with chronic heart failure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568271. [PMID: 38045233 PMCID: PMC10690294 DOI: 10.1101/2023.11.22.568271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Aims Heart failure (HF) patients often suffer from cognitive decline, depression, and mood impairments, but the molecular signals and brain circuits underlying these effects remain elusive. The hypothalamic neuropeptide oxytocin (OT) is critically involved in the regulation of mood, and OTergic signaling in the central amygdala (CeA) is a key mechanism controlling emotional responses including anxiety-like behaviors. Based on this, we used in this study a well-established ischemic rat HF model and aimed to study alterations in the hypothalamus-to-CeA OTergic circuit. Methods and Results To study potential HF-induced changes in the hypothalamus-to-CeA OTertic circuit, we combined patch-clamp electrophysiology, immunohistochemical analysis, RNAScope assessment of OTR mRNA, brain region-specific stereotaxic injections of viral vectors and retrograde tracing, optogenetic stimulation and OT biosensors in the ischemic HF model. We found that most of OTergic innervation of the central amygdala (CeA) originated from the hypothalamic supraoptic nucleus (SON). While no differences in the numbers of SON→CeA OTertic neurons (or their OT content) was observed between sham and HF rats, we did observe a blunted content and release of OT from axonal terminals within the CeA. Moreover, we report downregulation of neuronal and astrocytic OT receptors, and impaired OTR-driven GABAergic synaptic activity within the CeA microcircuit of rats with HF. Conclusions Our study provides first evidence that HF rats display various perturbations in the hypothalamus-to-amygdala OTergic circuit, and lays the foundation for future translational studies targeting either the OT system or GABAergic amygdala GABA microcircuit to ameliorate depression or mood impairments in rats or patients with chronic HF.
Collapse
|
5
|
Silver R, Yao Y, Roy RK, Stern JE. Parallel trajectories in the discovery of the SCN-OVLT and pituitary portal pathways: Legacies of Geoffrey Harris. J Neuroendocrinol 2023; 35:e13245. [PMID: 36880566 PMCID: PMC10423749 DOI: 10.1111/jne.13245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 02/16/2023]
Abstract
A map of central nervous system organization based on vascular networks provides a layer of organization distinct from familiar neural networks or connectomes. As a well-established example, the capillary networks of the pituitary portal system enable a route for small amounts of neurochemical signals to reach local targets by traveling along specialized pathways, thereby avoiding dilution in the systemic circulation. The first evidence of such a pathway in the brain came from anatomical studies identifying a portal pathway linking the hypothalamus and the pituitary gland. Almost a century later, we demonstrated a vascular portal pathway that joined the capillary beds of the suprachiasmatic nucleus and a circumventricular organ, the organum vasculosum of the lamina terminalis, in a mouse brain. For each of these portal pathways, the anatomical findings opened many new lines of inquiry, including the determination of the direction of flow of information, the identity of the signal that flowed along this pathway, and the function of the signals that linked the two regions. Here, we review landmark steps to these discoveries and highlight the experiments that reveal the significance of portal pathways and more generally, the implications of morphologically distinct nuclei sharing capillary beds.
Collapse
|
6
|
Althammer F, Roy RK, Kirchner MK, Campos-Lira E, Whitley KE, Davis S, Montanez J, Ferreira-Neto HC, Danh J, Feresin R, Biancardi VC, Zafar U, Parent MB, Stern JE. Angiotensin II-Mediated Neuroinflammation in the Hippocampus Contributes to Neuronal Deficits and Cognitive Impairment in Heart Failure Rats. Hypertension 2023; 80:1258-1273. [PMID: 37035922 PMCID: PMC10192104 DOI: 10.1161/hypertensionaha.123.21070] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/22/2023] [Indexed: 04/11/2023]
Abstract
BACKGROUND Heart failure (HF) is a debilitating disease affecting >64 million people worldwide. In addition to impaired cardiovascular performance and associated systemic complications, most patients with HF suffer from depression and substantial cognitive decline. Although neuroinflammation and brain hypoperfusion occur in humans and rodents with HF, the underlying neuronal substrates, mechanisms, and their relative contribution to cognitive deficits in HF remains unknown. METHODS To address this critical gap in our knowledge, we used a well-established HF rat model that mimics clinical outcomes observed in the human population, along with a multidisciplinary approach combining behavioral, electrophysiological, neuroanatomical, molecular and systemic physiological approaches. RESULTS Our studies support neuroinflammation, hypoperfusion/hypoxia, and neuronal deficits in the hippocampus of HF rats, which correlated with the progression and severity of the disease. An increased expression of AT1aRs (Ang II [angiotensin II] receptor type 1a) in hippocampal microglia preceded the onset of neuroinflammation. Importantly, blockade of AT1Rs with a clinically used therapeutic drug (Losartan), and delivered in a clinically relevant manner, efficiently reversed neuroinflammatory end points (but not hypoxia ones), resulting in turn in improved cognitive performance in HF rats. Finally, we show than circulating Ang II can leak and access the hippocampal parenchyma in HF rats, constituting a possible source of Ang II initiating the neuroinflammatory signaling cascade in HF. CONCLUSIONS In this study, we identified a neuronal substrate (hippocampus), a mechanism (Ang II-driven neuroinflammation) and a potential neuroprotective therapeutic target (AT1aRs) for the treatment of cognitive deficits in HF.
Collapse
|
7
|
Althammer F, Roy RK, Lefevre A, Najjar RS, Schoenig K, Bartsch D, Eliava M, Feresin RG, Hammock EA, Murphy AZ, Charlet A, Grinevich V, Stern JE. Altered PVN-to-CA2 hippocampal oxytocin pathway and reduced number of oxytocin-receptor expressing astrocytes in heart failure rats. J Neuroendocrinol 2022; 34:e13166. [PMID: 35657290 PMCID: PMC9495289 DOI: 10.1111/jne.13166] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 11/28/2022]
Abstract
Oxytocinergic actions within the hippocampal CA2 are important for neuromodulation, memory processing and social recognition. However, the source of the OTergic innervation, the cellular targets expressing the OT receptors (OTRs) and whether the PVN-to-CA2 OTergic system is altered during heart failure (HF), a condition recently associated with cognitive and mood decline, remains unknown. Using immunohistochemistry along with retrograde monosynaptic tracing, RNAscope and a novel OTR-Cre rat line, we show that the PVN (but not the supraoptic nucleus) is an important source of OTergic innervation to the CA2. These OTergic fibers were found in many instances in close apposition to OTR expressing cells within the CA2. Interestingly, while only a small proportion of neurons were found to express OTRs (~15%), this expression was much more abundant in CA2 astrocytes (~40%), an even higher proportion that was recently reported for astrocytes in the central amygdala. Using an established ischemic rat heart failure (HF) model, we found that HF resulted in robust changes in the PVN-to-CA2 OTergic system, both at the source and target levels. Within the PVN, we found an increased OT immunoreactivity, along with a diminished OTR expression in PVN neurons. Within the CA2 of HF rats, we observed a blunted OTergic innervation, along with a diminished OTR expression, which appeared to be restricted to CA2 astrocytes. Taken together, our studies highlight astrocytes as key cellular targets mediating OTergic PVN inputs to the CA2 hippocampal region. Moreover, they provide the first evidence for an altered PVN-to-CA2 OTergic system in HF rats, which could potentially contribute to previously reported cognitive and mood impairments in this animal model.
Collapse
|
8
|
Roy RK, Ferreira-Neto HC, Felder RB, Stern JE. Angiotensin II inhibits the A-type K + current of hypothalamic paraventricular nucleus neurons in rats with heart failure: role of MAPK-ERK1/2 signaling. Am J Physiol Regul Integr Comp Physiol 2022; 322:R526-R534. [PMID: 35319903 PMCID: PMC9076419 DOI: 10.1152/ajpregu.00308.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/03/2022] [Accepted: 03/18/2022] [Indexed: 11/22/2022]
Abstract
Angiotensin II (ANG II)-mediated sympathohumoral activation constitutes a pathophysiological mechanism in heart failure (HF). Although the hypothalamic paraventricular nucleus (PVN) is a major site mediating ANG II effects in HF, the precise mechanisms by which ANG II influences sympathohumoral outflow from the PVN remain unknown. ANG II activates the ubiquitous intracellular MAPK signaling cascades, and recent studies revealed a key role for ERK1/2 MAPK signaling in ANG II-mediated sympathoexcitation in HF rats. Importantly, ERK1/2 was reported to inhibit the transient outward potassium current (IA) in hippocampal neurons. Given that IA is a critical determinant of the PVN neuronal excitability, and that downregulation of IA in the brain has been reported in cardiovascular disease states, including HF, we investigated here whether ANG II modulates IA in PVN neurons via the MAPK-ERK pathway, and, whether these effects are altered in HF rats. Patch-clamp recordings from identified magnocellular neurosecretory neurons (MNNs) and presympathetic (PS) PVN neurons revealed that ANG II inhibited IA in both PVN neuronal types, both in sham and HF rats. Importantly, ANG II effects were blocked by inhibiting MAPK-ERK signaling as well as by inhibiting epidermal growth factor receptor (EGFR), a gateway to MAPK-ERK signaling. Although no differences in basal IA magnitude were found between sham and HF rats under normal conditions, MAPK-ERK blockade resulted in significantly larger IA in both PVN neuronal types in HF rats. Taken together, our studies show that ANG II-induced ERK1/2 activity inhibits IA, an effect expected to increase the excitability of presympathetic and neuroendocrine PVN neurons, contributing in turn to the neurohumoral overactivity that promotes progression of the HF syndrome.
Collapse
|
9
|
Roy RK, Althammer F, Seymour AJ, Du W, Biancardi VC, Hamm JP, Filosa JA, Brown CH, Stern JE. Inverse neurovascular coupling contributes to positive feedback excitation of vasopressin neurons during a systemic homeostatic challenge. Cell Rep 2021; 37:109925. [PMID: 34731601 PMCID: PMC9488983 DOI: 10.1016/j.celrep.2021.109925] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 08/09/2021] [Accepted: 10/12/2021] [Indexed: 01/03/2023] Open
Abstract
Neurovascular coupling (NVC), the process that links neuronal activity to cerebral blood flow changes, has been mainly studied in superficial brain areas, namely the neocortex. Whether the conventional, rapid, and spatially restricted NVC response can be generalized to deeper and functionally diverse brain regions remains unknown. Implementing an approach for in vivo two-photon imaging from the ventral surface of the brain, we show that a systemic homeostatic challenge, acute salt loading, progressively increases hypothalamic vasopressin (VP) neuronal firing and evokes a vasoconstriction that reduces local blood flow. Vasoconstrictions are blocked by topical application of a VP receptor antagonist or tetrodotoxin, supporting mediation by activity-dependent, dendritically released VP. Salt-induced inverse NVC results in a local hypoxic microenvironment, which evokes positive feedback excitation of VP neurons. Our results reveal a physiological mechanism by which inverse NVC responses regulate systemic homeostasis, further supporting the notion of brain heterogeneity in NVC responses.
Collapse
|
10
|
Althammer F, Ferreira-Neto HC, Rubaharan M, Roy RK, Patel AA, Murphy A, Cox DN, Stern JE. Correction to: Three-dimensional morphometric analysisreveals time-dependent structural changesin microglia and astrocytes in the centralamygdala and hypothalamicparaventricular nucleus of heart failure rats. J Neuroinflammation 2020; 17:348. [PMID: 33222695 PMCID: PMC7680589 DOI: 10.1186/s12974-020-02035-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
An amendment to this paper has been published and can be accessed via the original article.
Collapse
|
11
|
Althammer F, Ferreira-Neto HC, Rubaharan M, Roy RK, Patel AA, Murphy A, Cox DN, Stern JE. Three-dimensional morphometric analysis reveals time-dependent structural changes in microglia and astrocytes in the central amygdala and hypothalamic paraventricular nucleus of heart failure rats. J Neuroinflammation 2020; 17:221. [PMID: 32703230 PMCID: PMC7379770 DOI: 10.1186/s12974-020-01892-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/08/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Cardiovascular diseases, including heart failure, are the most common cause of death globally. Recent studies support a high degree of comorbidity between heart failure and cognitive and mood disorders resulting in memory loss, depression, and anxiety. While neuroinflammation in the hypothalamic paraventricular nucleus contributes to autonomic and cardiovascular dysregulation in heart failure, mechanisms underlying cognitive and mood disorders in this disease remain elusive. The goal of this study was to quantitatively assess markers of neuroinflammation (glial morphology, cytokines, and A1 astrocyte markers) in the central amygdala, a critical forebrain region involved in emotion and cognition, and to determine its time course and correlation to disease severity during the progression of heart failure. METHODS We developed and implemented a comprehensive microglial/astrocyte profiler for precise three-dimensional morphometric analysis of individual microglia and astrocytes in specific brain nuclei at different time points during the progression of heart failure. To this end, we used a well-established ischemic heart failure rat model. Morphometric studies were complemented with quantification of various pro-inflammatory cytokines and A1/A2 astrocyte markers via qPCR. RESULTS We report structural remodeling of central amygdala microglia and astrocytes during heart failure that affected cell volume, surface area, filament length, and glial branches, resulting overall in somatic swelling and deramification, indicative of a change in glial state. These changes occurred in a time-dependent manner, correlated with the severity of heart failure, and were delayed compared to changes in the hypothalamic paraventricular nucleus. Morphometric changes correlated with elevated mRNA levels of pro-inflammatory cytokines and markers of reactive A1-type astrocytes in the paraventricular nucleus and central amygdala during heart failure. CONCLUSION We provide evidence that in addition to the previously described hypothalamic neuroinflammation implicated in sympathohumoral activation during heart failure, microglia, and astrocytes within the central amygdala also undergo structural remodeling indicative of glial shifts towards pro-inflammatory phenotypes. Thus, our studies suggest that neuroinflammation in the amygdala stands as a novel pathophysiological mechanism and potential therapeutic target that could be associated with emotional and cognitive deficits commonly observed at later stages during the course of heart failure.
Collapse
|
12
|
Brown CH, Roy RK, Hamm JP, Stern JE. Development of a Novel Approach for Real‐Time Two‐Photon Imaging of the Rat Hypothalamus In Vivo. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.04797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
13
|
Roy RK, Augustine RA, Brown CH, Schwenke DO. Acute myocardial infarction activates magnocellular vasopressin and oxytocin neurones. J Neuroendocrinol 2019; 31:e12808. [PMID: 31715034 DOI: 10.1111/jne.12808] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 12/31/2022]
Abstract
Myocardial infarction (MI) is a leading cause of death worldwide. For those who survive the acute insult, the progressive dilation of the ventricle associated with chronic heart failure is driven by an adverse increase in circulating levels of the antidiuretic hormone, vasopressin, which is secreted from hypothalamic supraoptic (SON) and paraventricular nuclei (PVN) nerve terminals. Although increased vasopressin neuronal activity has been demonstrated in the latter stages of chronic heart failure, we hypothesised that vasopressin neurones become activated immediately following an acute MI. Male Sprague-Dawley rats were anaesthetised and an acute MI was induced by ligation of the left anterior descending coronary artery. After 90 minutes of myocardial ischaemia, brains were collected. Dual-label immunohistochemistry was used to quantify the expression of Fos protein, a marker of neuronal activation, within vasopressin- or oxytocin-labelled neurones of the hypothalamic PVN and SON. Fos protein and tyrosine hydroxylase within the brainstem were also quantified. The results obtained show that the expression of Fos in both vasopressin and oxytocin neurones of the PVN and SON was significantly elevated as soon as 90 minutes post-MI compared to sham rats. Moreover, Fos protein was also elevated in tyrosine hydroxylase neurones in the nucleus tractus solitarius and rostral ventrolateral medulla of MI rats than sham rats. We conclude that magnocellular vasopressin and oxytocin neuronal activation occurs immediately following acute MI, rather than in the later stages of chronic heart failure. Therefore, prompt vasopressin antagonist therapy as an adjunct treatment for acute MI may impede the progression of ventricular dilatation, which remains a key adverse hallmark of chronic heart failure.
Collapse
|
14
|
Roy RK, Augustine RA, Brown CH, Schwenke DO. Activation of oxytocin neurons in the paraventricular nucleus drives cardiac sympathetic nerve activation following myocardial infarction in rats. Commun Biol 2018; 1:160. [PMID: 30320228 PMCID: PMC6172223 DOI: 10.1038/s42003-018-0169-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 09/10/2018] [Indexed: 01/16/2023] Open
Abstract
Myocardial infarction (MI) initiates an increase in cardiac sympathetic nerve activity (SNA) that facilitates potentially fatal arrhythmias. The mechanism(s) underpinning sympathetic activation remain unclear. Some neuronal populations within the hypothalamic paraventricular nucleus (PVN) have been implicated in SNA. This study elucidated the role of the PVN in triggering cardiac SNA following MI (left anterior descending coronary artery ligation). By means of c-Fos, oxytocin, and vasopressin immunohistochemistry accompanied by retrograde tracing we showed that MI activates parvocellular oxytocin neurons projecting to the rostral ventral lateral medulla. Central inhibition of oxytocin receptors using atosiban (4.5 µg in 5 µl, i.c.v.), or retosiban (3 mg/kg, i.v.), prevented the MI-induced increase in SNA and reduced the incidence of ventricular arrhythmias and mortality. In conclusion, pre-autonomic oxytocin neurons can drive the increase in cardiac SNA following MI and peripheral administration of an oxytocin receptor blocker could be a plausible therapeutic strategy to improve outcomes for MI patients. Roy et al. showed that activation of parvocellular pre-autonomic oxytocin neurons increased sympathetic nerve activity following myocardial infarction. This and other aberrant physiological changes induced by acute myocardial infarction were decreased by oxytocin receptor antagonists, hinting to their potential therapeutic role.
Collapse
|
15
|
Singh N, Pal AK, Roy RK, Tewari SK, Tamta S, Rana TS. Characterization of Gladiolus Germplasm Using Morphological, Physiological, and Molecular Markers. Biochem Genet 2017; 56:128-148. [PMID: 29260377 DOI: 10.1007/s10528-017-9835-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 12/13/2017] [Indexed: 11/28/2022]
Abstract
Estimation of variability and genetic relationships among breeding materials is one of the important strategies in crop improvement programs. Morphological (plant height, spike length, a number of florets/spike), physiological (chlorophyll content, chlorophyll fluorescence, and rapid light curve parameters) and Directed amplification of minisatellite DNA (DAMD) markers were used to investigate the relationships among 50 Gladiolus cultivars. Cluster analysis based on morphological data, physiological characteristics, molecular markers, and cumulative data discriminated all cultivars into seven, five, seven, and six clusters in the unweighted pair-group method using arithmetic mean (UPGMA) dendrogram, respectively. The results of the principal coordinate analysis (PCoA) also supported UPGMA clustering. Variations among the Gladiolus cultivars at phenotypic level could be due to the changes in physiology, environmental conditions, and genetic variability. DAMD analysis using 10 primers produced 120 polymorphic bands with 80% polymorphism showing polymorphic information content (PIC = 0.28), Marker index (MI = 3.37), Nei's gene diversity (h = 0.267), and Shannon's information index (I = 0.407). Plant height showed a positive significant correlation with Spike length and Number of florets/spike (r = 0.729, p < 0.001 and r = 0.448, p = 0.001 respectively). Whereas, Spike length showed positive significant correlation with Number of florets/spike (r = 0.688, p < 0.001) and Chlorophyll content showed positive significant correlation with Electron transport rate (r = 0.863, p < 0.001). Based on significant morphological variations, high physiological performance, high genetic variability, and genetic distances between cultivars, we have been able to identify diverse cultivars of Gladiolus that could be the potential source as breeding material for further genetic improvement in this ornamental crop.
Collapse
|
16
|
Kumar R, Sirohi TS, Singh H, Yadav R, Roy RK, Chaudhary A, Pandeya SN. 1,2,4-triazine analogs as novel class of therapeutic agents. Mini Rev Med Chem 2014; 14:168-207. [PMID: 24479860 DOI: 10.2174/1389557514666140131111837] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 12/10/2013] [Accepted: 12/18/2013] [Indexed: 11/22/2022]
Abstract
1,2,4-Triazine nucleus is a prominent structural core system present in numerous pharmacologically active compounds. Till date, various 1,2,4-triazine analogs, possesing a wide range of potent pharmacological activities, have been reported. This review is an attempt to compile the medicinal chemistry aspects of various synthesized 1,2,4-triazine analogs reported so far.
Collapse
|
17
|
Nayak C, Siddqui VA, Rajpal R, Singh VK, Singh H, Pal R, Singh V, Roy RK. Saraca Indica: A Multicentric Double Blind Homoeopathic Pathogenetic Trial. INDIAN JOURNAL OF RESEARCH IN HOMOEOPATHY 2009. [DOI: 10.53945/2320-7094.1852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
|
18
|
Rauniyar GP, Roy RK, Das BP, Bhandari G, Bhattacharya SK. Prescription Writing Skills of Pre-Clinical Medical and Dental Undergraduate Students. JNMA J Nepal Med Assoc 2008. [DOI: 10.31729/jnma.157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Objective of this prospective study was to assess the acquisition of prescribing skill of preclinicalmedical and dental undergraduate students. Prescription writing skills of 258 students of both firstand second year of MBBS and BDS students were analyzed through an objective structured practicalexamination. MBBS student of second year scored 85.01% and 92.82% respectively in physician anddrug related component whereas first year MBBS students scored 89.9% and 83.4%. BDS studentof first year scored 91.96% and 86.33% in physician and drug related components which is betterthan second year that scored 83.33% and 77.94% respectively. This study revealed that the studentsof both courses acquire prescribing skills to a limited extent during preclinical phase. Prescribingerrors were found both in physician and drug related components. To minimize the different form ofprescribing errors vigorous training in the internship period will help to minimize prescribing errorsand improve rational prescribing too.Key words: dental, examination, medical, objective, prescription, student
Collapse
|
19
|
Rauniar GP, Roy RK, Das BP, Bhandari G, Bhattacharya SK. Prescription writing skills of pre-clinical medical and dental undergraduate students. JNMA J Nepal Med Assoc 2008; 47:197-200. [PMID: 19079394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Objective of this prospective study was to assess the acquisition of prescribing skill of preclinical medical and dental undergraduate students. Prescription writing skills of 258 students of both first and second year of MBBS and BDS students were analyzed through an objective structured practical examination. MBBS student of second year scored 85.01% and 92.82% respectively in physician and drug related component whereas first year MBBS students scored 89.9% and 83.4%. BDS student of first year scored 91.96% and 86.33% in physician and drug related components which is better than second year that scored 83.33% and 77.94% respectively. This study revealed that the students of both courses acquire prescribing skills to a limited extent during preclinical phase. Prescribing errors were found both in physician and drug related components. To minimize the different form of prescribing errors vigorous training in the internship period will help to minimize prescribing errors and improve rational prescribing too.
Collapse
|
20
|
Bhattacharya SK, Madan M, Mahajan P, Paudel KR, Rauniar GP, Das BP, Roy RK. Relationship between plasma leptin and plasma insulin levels in type-2 diabetic patients before and after treatment with glibenclamide and glimepiride. INDIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY 2008; 52:43-52. [PMID: 18831351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Type 2 diabetes affects 100 million people throughout the world. Among the various factors implicated in the causation of this disease, the role of leptin, an obesity gene product, is increasingly being investigated. This especially assumes importance in the light of knowledge that obesity confers a minimum of 3-10 fold higher risk of diabetes. This study was planned to investigate the relationship between leptin and insulin levels in type 2 diabetic patients before and after treatment with glibenclamide or glimepiride. 60 type 2 diabetic patients were recruited for the study and were divided into 2 groups-one receiving glimepiride and the other group receiving glibenclamide for duration of 10 weeks. This study demonstrated a highly positive correlation of plasma leptin levels with BMI, plasma insulin and insulin resistance. No gender specific differences were observed in leptin concentrations. The study, however, failed to demonstrate any possible relationship between glycemic control as assessed by blood sugars/ glycosylated hemoglobin (HbAlc) and plasma leptin. The administration of glibenclamide or glimepiride significantly lowered blood glucose levels coupled with a decrease in (HbAlc). Both the drugs increased insulin concentrations. Glibenclamide increased leptin levels but they remained unaltered with glimepiride. Glibenclamide and glimepiride were found to be equally effective in their glucose lowering action. However, the patients receiving glibenclamide experienced higher episode of hypoglycaemic spells than those receiving glimepiride.
Collapse
|
21
|
Hussain S, Datta S, Roy RK, Pal AK. Surface plasmon resonance in nanocrystalline gold-copper alloy films. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2007; 7:4486-4493. [PMID: 18283832 DOI: 10.1166/jnn.2007.907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Nanocrystalline Au(x)Cu(1-x) films were synthesized by depositing Cu/Au/Cu multilayer in nanocrystalline thin film form with requisite thickness of individual layers onto fused silica substrates by high pressure sputtering technique. The absorbance spectra showed only one surface plasmon peak for all the compositions with the exception that the peak position did not indicate gradual shift as gold concentration was increased. Peak position for the two compositions corresponding to the two superlattice structures, AuCu3 and AuCu, deviated significantly from linear variation. The experimental results have been discussed in light of the existing Mie theory and the Core-shell model.
Collapse
|
22
|
Mukhopadhyay BP, Ghosh B, Bairagya HR, Bera AK, Roy RK. Conserved Water Molecular Dynamics of the Different X-ray Structures of Rusticyanin: An Unique Aquation Potentiality of the Ligand Bonded Cu++Center. J Biomol Struct Dyn 2007; 24:369-78. [PMID: 17206852 DOI: 10.1080/07391102.2007.10507126] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The invariant water molecular interaction involving in the Rusticyanin of Thiobacillus ferrooxidans is thought to be important for its molecular complexation with other proteins at differential acidophilic situation. The comparative analysis of the different x-ray, energy minimized, and auto solvated structures of Rusticyanin revealed the presence of five specific invariant bound water molecules (among the approximately 150 water molecules per monomer) in the crystals. The five W 205, W 206, W 112, W 214, and W 221 water molecules (in Rusticyanin PDB code: 1RCY) were seem to be invariant in all the seven structures (PDB codes: 1RCY, 1A3Z, 1A8Z, 1E3O, 1GY1, 1GY2, 2CAL). Among the five conserved water molecules the W 221 (of 1 RCY or the equivalent water molecules in the other oxidized form of Rusticyanin structures) had endowed an interesting coordination potentiality to Cu(+2) ion during the energy minimization. The W 221 was observed to approach toward the tetrahedrally bonded Cu(+2) ion through the opposite (or trans) route of metal-bonded Met 148. This direct water molecular coordination affected the tetrahedral geometry of Cu(+2) to trigonal bipyramidal. Presumably this structural dynamics at the Cu(+2) center could involve in the electron transport process during protein-protein complexation.
Collapse
|
23
|
Sharma SC, Srivastava R, Roy RK. Role of bougainvilleas in mitigation of environmental pollution. JOURNAL OF ENVIRONMENTAL SCIENCE & ENGINEERING 2005; 47:131-4. [PMID: 16649617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Environmental pollution adversely affects health of the people. Industrialization, urbanization, over exploitation of natural resources and increasing number of automobiles have aggravated the pollution manifold though there are various ways to mitigate the environmental pollution. Bio-remediation by using selected plant species is an effective method to control pollution which is universally accepted. Bougainvillea is a pollution tolerant plant and can help in the mitigation of air pollution besides its ornamental value in the landscaping. From the rich germplasm collection in NBRI Botanical Garden, tolerant plants have been experimented for road side plantation in view of mitigating the environmental pollution.
Collapse
|
24
|
Usharani K, Roy RK, Prakash J. Nutritional status of cancer patients given different treatment modalities. Int J Food Sci Nutr 2004; 55:363-9. [PMID: 15545044 DOI: 10.1080/09637480400002867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The nutritional status of 91 cancer patients was assessed at the time of diagnosis and follow-up assessments were carried out at the third and sixth week after initiating different treatment modalities to study the effect of type and duration of treatment on nutritional status. Parameters assessed were anthropometry, biochemical status and clinical signs and symptoms of nutritional deficiencies. Treatment modalities studied were radiotherapy, chemotherapy, chemotherapy+radiotherapy, and combined treatment modality (surgery+radiotherapy+chemotherapy). The nutritional status of male patients was affected most by chemotherapy+radiotherapy while females were affected most with radiotherapy. Biochemical parameters showed a marginal decline in total serum protein and serum albumin concentrations. Haemoglobin concentrations declined substantially with radiotherapy and chemotherapy. The lymphocyte count decreased substantially irrespective of the treatment modality. Clinical examination revealed increased incidences of deficiency signs and symptoms in all patients during follow-up irrespective of treatment modality.
Collapse
|
25
|
Haq Z, Rahman M, Siddique MA, Roy RK, Rahman AM, Khatun M. Interleukin-6 (IL-6) and tumour necrosis factor-alpha in open and laparoscopic cholecystectomy. Mymensingh Med J 2004; 13:153-6. [PMID: 15284691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Injury to the human body alters normal physiology across several systems and these alterations are proportional to the extent of the injury. Physiological response to minimally invasive surgery appears to be different than those of traditional open surgery. Acute phase protein response appears to be one example. The important cytokines that are known as major mediators of acute phase response are interleukin-6 and TNF-alpha. Thirty patients were studied in which 14 underwent open cholecystectomy and 16 laparoscopic cholecystectomy. Three blood samples were taken from each patient, one pre-operatively and 2 post operatively at 4 and 24 hours. Interleukin-6 and Tumour Necrosis Factor-alpha (TNF-alpha) were raised significantly in post operative blood sample in both groups but the rise was much more in open group than laparoscopic group. This suggest less stress response in laparoscopic group which also showed a direct effect on patient convalescence in terms of less pain, less analgesic requirement and shorter hospital stay
Collapse
|