A5037845007- Neuroendocrine regulation and behavior
- Neuroscience and Neuropharmacology Research
- Stress Responses and Cortisol
- Neuroscience of respiration and sleep
- Receptor Mechanisms and Signaling
- Circadian rhythm and melatonin
- Cannabis and Cannabinoid Research
- Sleep and Wakefulness Research
- Regulation of Appetite and Obesity
- Tryptophan and brain disorders
- Ion channel regulation and function
- Photoreceptor and optogenetics research
- Hormonal Regulation and Hypertension
- Neural dynamics and brain function
- Infant Health and Development
- Estrogen and related hormone effects
- Memory and Neural Mechanisms
- Neuropeptides and Animal Physiology
- Epilepsy research and treatment
- Hypothalamic control of reproductive hormones
- Neuroscience and Neural Engineering
- Biochemical effects in animals
- Neuroinflammation and Neurodegeneration Mechanisms
- Adipose Tissue and Metabolism
- Pancreatic function and diabetes
Tulane University
2015-2024
Southeast Louisiana Veterans Health Care System
2023
Institute of Molecular and Cell Biology
2013-2016
Zero to Three
2011
Louisiana State University Health Sciences Center New Orleans
2006
Institute of Cell Biology and Neurobiology
2005
Society for Neuroscience
2000-2002
University of the Witwatersrand
2000
University of California, Los Angeles
1989-1996
Oklahoma State University Center for Health Sciences
1991
Glucocorticoid negative feedback in the brain controls stress, feeding, and neural-immune interactions by regulating hypothalamic—pituitary—adrenal axis, but mechanisms of inhibition hypothalamic neurosecretory cells have never been elucidated. Using whole-cell patch-clamp recordings an acute slice preparation, we demonstrate a rapid suppression excitatory glutamatergic synaptic inputs to parvocellular neurons paraventricular nucleus (PVN) glucocorticoids dexamethasone corticosterone. The...
Glucocorticoid hormones are secreted in response to stimuli that activate the hypothalamo-pituitary-adrenocortical (HPA) axis and self-regulate through negative feedback. Negative feedback occurs on a rapid time scale is thought act nongenomic mechanisms. In these studies, we investigated fast inhibition of HPA stress responses by direct glucocorticoid action at paraventricular nucleus hypothalamus (PVN). Local infusion dexamethasone or membrane-impermeant dexamethasone-BSA conjugate into...
Stress activation of the hypothalamic–pituitary–adrenal (HPA) axis culminates in increased circulating corticosteroid concentrations. Stress-induced corticosteroids exert diverse actions multiple target tissues over a broad range timescales, ranging from rapid actions, which are induced within seconds to minutes and gene transcription independent, slow delayed, long lasting, dependent. Rapid brain include, among others, fast negative feedback mechanism responsible for shutting down activated...
Local inhibitory synaptic inputs to neurons of the rat hypothalamic paraventricular nucleus (PVN) were studied by using glutamate microstimulation and conventional intracellular whole-cell patch-clamp recordings in coronal, horizontal, parasagittal slices hypothalamus. PVN cells classified as magnocellular or parvocellular on basis electrophysiological post hoc immunohistochemical analyses; GABA-producing localized with situ hybridization. Glutamate different sites around evoked volleys...
Glucocorticoids secreted in response to stress activation of the hypothalamic-pituitary-adrenal axis feed back onto brain rapidly suppress neuroendocrine activation, including oxytocin and vasopressin secretion. Here we show using whole-cell patch clamp recordings that glucocorticoids elicit a rapid, opposing action on synaptic glutamate gamma-aminobutyric acid (GABA) release magnocellular neurons hypothalamic supraoptic nucleus paraventricular nucleus, suppressing facilitating GABA by...
The hypothalamic paraventricular nucleus (PVN) integrates preautonomic and neuroendocrine control of energy homeostasis, fluid balance, the stress response. We recently demonstrated that glucocorticoids act via a membrane receptor to rapidly cause endocannabinoid-mediated suppression synaptic excitation in PVN neurosecretory neurons. Leptin, major signal nutritional state, suppresses CB<sub>1</sub> cannabinoid receptor-dependent hyperphagia (increased appetite) fasting animals by reducing...
1. Neurones in the region of hypothalamic paraventricular nucleus (PVN) rat were studied with intracellular recording coronal slice preparation. Three types neurones distinguished according to their membrane properties and anatomical positions. Lucifer Yellow or ethidium bromide was injected intracellularly determine morphology some recorded cells. 2. The most distinctive electrophysiological characteristic low‐threshold depolarizing potentials which totally absent type I neurones, present...
Glucocorticoids exert an opposing rapid regulation of glutamate and GABA synaptic inputs to hypothalamic magnocellular neurons via the activation postsynaptic membrane-associated receptors release retrograde messengers. suppress endocannabinoids facilitate unknown messenger. Here, we show that glucocorticoid facilitation is due neuronal nitric oxide glucocorticoid-induced endocannabinoid synthesis are mediated by divergent G-protein signaling mechanisms. While glucocorticoid-induced,...
We conducted whole cell voltage-clamp and current-clamp recordings in slices of rat hypothalamus to test for local excitatory synaptic circuits. Local inputs neurons the paraventricular nucleus (PVN) supraoptic (SON) were studied with use electrical chemical stimulation. Extracellular stimulation provided indirect evidence Single stimuli evoked multiple postsynaptic potentials (EPSPs) or currents (EPSCs) some PVN SON cells, invoking polysynaptic inputs. Repetitive (10-20 Hz, 2-10 s) elicited...
Abstract Chronic stress precipitates pronounced enhancement of central excitability, marked by sensitization hypothalamic‐pituitary‐adrenocortical (HPA) axis responses and increased adrenocorticotropic hormone (ACTH) secretagogue biosynthesis in the paraventricular nucleus hypothalamus (PVN). stress‐induced HPA excitability predicts excitatory and/or decreased inhibitory innervation parvocellular PVN. We tested this hypothesis evaluating chronic variable (CVS)‐induced changes total...
Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been implicated in a range affective and stress-related disorders. The regulatory systems that control HPA activity are subject to modulation by environmental influences, stressful life events or circumstances can promote subsequent dysregulation. brain is major regulator axis, stress-induced plasticity neural circuitry involved regulation might constitute an etiological link between stress development This review focuses on...
Stress and glucocorticoids stimulate the rapid mobilization of endocannabinoids in basolateral amygdala (BLA). Cannabinoid receptors BLA contribute to anxiogenesis fear-memory formation. We tested for glucocorticoid-induced endocannabinoid regulation synaptic inhibition rat BLA. Glucocorticoid application slices elicited a rapid, nonreversible suppression spontaneous, but not evoked, GABAergic currents principal neurons; effect was also seen with membrane-impermeant glucocorticoid,...
Magnocellular and parvocellular neurones of the hypothalamic paraventricular nucleus (PVN) differentially regulate pituitary hormone secretion autonomic output. Previous experiments have suggested that magnocellular, or type I neurones, parvocellular, II PVN express different electrophysiological properties. Whole‐cell patch‐clamp recordings were performed in slices to identify voltage‐gated currents responsible for differences between neurones. Type which display transient outward...
Noradrenergic projections to the hypothalamus play a critical role in afferent control of oxytocin and vasopressin release. Recent evidence for intrahypothalamic glutamatergic circuits prompted us test hypothesis that excitatory effect noradrenergic inputs on release is mediated part by local interneurons. The voltage response norepinephrine (30-300 microM) was tested with whole-cell recordings putative magnocellular neurons paraventricular nucleus (PVN) hypothalamic slices (400...
Schrader, L. A. and J. G. Tasker. Presynaptic modulation by metabotropic glutamate receptors of excitatory inhibitory synaptic inputs to hypothalamic magnocellular neurons. Neurophysiol. 77: 527–536, 1997. The effects activation (mGluRs) on neurons the supraoptic nucleus (SON) were studied with use whole cell patch-clamp microelectrode recordings in acute slices. Application mGluR agonist trans-(±)-1-amino-1,3-cyclopentane dicarboxylic acid ( trans-ACPD, 100 μM) elicited an increase...
The neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone) facilitates GABA(A) receptor-mediated ionic currents via allosteric modulation of the receptor. Accordingly, allopregnanolone caused an increase in slow decay time constant spontaneous GABA-mediated IPSCs magnocellular neurons recorded hypothalamic slices. effect on was inhibited by a G-protein antagonist as well blocking protein kinase C and, to lesser extent, cAMP-dependent activities. and activation absence had no...
Parvocellular neurones of the hypothalamic paraventricular nucleus (PVN) comprise neurosecretory and non-neurosecretory subpopulations. We labelled with intravenous injection retrograde tracer, fluoro-gold, recorded from fluoro-gold-positive negative PVN parvocellular in slices. Non-neurosecretory generated a low-threshold spike (LTS) robust T-type Ca2+ current, whereas showed no LTS small T-current. were located regions PVN, non-LTS PVN. These findings indicate that subtypes express...