Norepinephrine Stores Research Articles

The halothane era in pediatric anesthesia: The convergence of a cardiac depressant anesthetic with the immature myocardium of infancy.

Introduced in the late 1950s, halothane became the anesthetic of choice for inhalational induction of children for over 40 years. Halothane enjoyed a generally favorable safety record during its time, but its cardiac contractility depressant effect-well tolerated by most age groups-was profoundly heightened in neonates and infants, leading to increased incidences of hypotension and cardiac arrest. The neonatal myocardium is immature and is characterized by poor ventricular compliance, poor contractility due to fewer contractile elements, immature sympathetic innervation with decreased norepinephrine stores, and immature mechanisms for storage and exchange of calcium in the sarcoplasmic reticulum. Invitro studies of myocardial contractility of mammalian fetal and adult myocardium demonstrated that the fetal heart was twice as sensitive to halothane as the adult. Clinical studies demonstrated that most neonates and infants less than 6 months of age experienced hypotension during halothane induction of anesthesia and significantly (p < .01) greater decreases in blood pressure than older children at equipotent concentrations of halothane. Intraoperative cardiac arrest during the halothane era occurred over twice as frequently in neonates aged less than 1 month than in infants aged 1-12 months and nearly 10 times more frequently than children 1-5 years of age. Halothane was associated with 66% of intraoperative drug-related cardiac arrests in children. The halothane era began to close in the late 1990s with the introduction of sevoflurane, which had a more favorable hemodynamic profile. Shortly thereafter, halothane was completely displaced from pediatric anesthesia practice in North America.

Norepinephrine Regulates Spatial Memory Consolidation Using Barnes Maze in Male, but Not Female Rats (P1-12.009)

<h3>Objective:</h3> Here, we study the role of NE on spatial learning and memory in rats using a Barnes maze assay. <h3>Background:</h3> The role of norepinephrine (NE) in learning and memory has been extensively studied, yet its contribution to different phases of memory, such as consolidation or updating, remains elusive. <h3>Design/Methods:</h3> We used a specific noradrenergic neurotoxin (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4)) to deplete central NE stores. In experiment one, Wistar rats (n=16/sex) were trained to reach a hidden goal box using visual and auditory cues for five days with three trials per day. Rats were administered 50 mg/kg/i.p of DSP-4 or saline ten days prior to training on the Barnes maze assay. DSP-4 mediated reduction of NE, but not serotonin or dopamine, was confirmed using HPLC in several brain regions. In experiment two, using female and male rats (n=16/sex), we replicated results of experiment one by utilizing two trials per day to increase the difficulty of learning the task and extended the findings by utilizing a single probe trial (memory consolidation) and a two-day reversal (memory updating) learning task. <h3>Results:</h3> In experiment one, female and male rats in DSP-4 and saline groups learned the location of the hidden zone, and this was measured by a reduction in latency to reach the goal box. Levels of NE were significantly lower in the dorsal hippocampus, cingulate cortex, and the striatum. Experiment two replicated these results and the subsequent behavioral analysis suggests that only male DSP-4 treated rats increased time spent in the covered hidden zone area during the probe trial. During the reversal learning task, DSP-4 treated males continued to visit the previously hidden platform despite learning the new goal location. <h3>Conclusions:</h3> These data suggest that NE plays a role in regulation of memory consolidation rather than acquisition or memory updating, and this regulation may be sex-specific. <b>Disclosure:</b> Ms. Simpson has nothing to disclose. Dr. Gheidi has nothing to disclose. Dr. Davidson has nothing to disclose. Mr. Yahya has nothing to disclose. Mrs. Trombley has nothing to disclose. Miss Sadik has received personal compensation for serving as an employee of Wayne State University . The institution of Dr. Perrine has received research support from NIH.

Dopamine Adjustment Difficulties in Special Pathophysiological Conditions

Dopamine is a commonly used drug but its biology and cellular action is not well known, its bizarre actions in neonates back to different pattern of receptors on vascular and metabolic excretion rate especially in preterm babies.[1] Dopamine’s physiological action is dose dependent and give maximum diuresis and natriuresis at the dose of 2 micrograms/kg/min compared to 4 micrograms/ kg/min in neonates.[2] Such physiological properties back to immature norepinephrine stores that halt inotropic effects and longer elimination half time related to age that accentuate side effects of dopamine such as tachycardia.[3] Such side effects may accentuate in renal and hepatic deficiency because of lower clearance of dopamine and risk of toxicities in usual doses administration.[4] The other challenging factor for easy administration of dopamine is various inter individual pharmacokinetics property of dopamine especially in seriously ill patients.[5] Cochran study in small sample of selected asphyxiated neonate cases showed low dose dopamine as low as 2.5 micrograms/kg/min cannot decrease mortality and morbidity compared to placebo[6] and doses as low as 7 micrograms/kg/min make pulmonary vasoconstriction in critically ill case and infusion rate of 5 micrograms/kg/min cannot bring target hemodynamic indices in a great proportion of patients (9 of 25) inspite of tachycardia occurred in them as a side effect without increase in stroke volume and modest reduction in systemic vascular resistance.[7-8] Dopamine, efficacy, decrement during lactic acidosis is another challenge in spite of the plasma norepinephrine level was elevated dramatically during severe lactic acid acidosis in compared to normal acidosis.[9]

Suspected Compartment Syndrome and Rhabdomyolysis after “Pseudoephedrine” Use: A Case Report

Acute compartment syndrome and rhabdomyolysis are two life threatening diagnoses that cannot be missed in the emergency room. The increased pressure in the closed compartments of extremities can eventually lead to loss of peripheral pulses, decreased tissue perfusion, and ultimately muscle necrosis. This breakdown of muscle byproducts will ultimately lead to kidney damage and rhabdomyolysis.&#x0D; Although the most common cause of compartment syndromes are secondary orthopedic causes such as lower extremity fractures there are known documented toxicological causes. (1,2)&#x0D; Pseudoephedrine, a sympathomimetic amine, is commonly used in the treatment of nasal congestion. Its primary mechanism directly acts on the adrenergic receptor system which stimulates release of stored norepinephrine from neurons. Its alpha-adrenergic effect is believed to be the cause of vasoconstriction in the body (3)&#x0D; Clinically, intoxication from sympathomimetic drugs have produced toxidromes with prominent features such as tachycardia, hypertension, hyperthermia, agitation, and delirium. However, it is incredibly rare to see an association with pseudoephedrine overdose and rhabdomyolysis and compartment syndrome. There are documented cases where sympathomimetic drugs have been associated with compartment syndrome (2,4,5)&#x0D; This case of a 29-year-old male with suspected pseudoephedrine abuse highlights the need for consideration of rhabdomyolysis and compartment syndrome being a possible complication from pseudoephedrine overdose.

3D reconstruction of the rat adrenal medulla.

We performed 3D reconstruction of the microscopic structure of the adrenal medulla of the adult rats using serial histological sections with histochemical differentiation of adrenaline-storing (A) and noradrenaline-storing (NA) cells. Medulla volume is 1.18±0.17mm3 . Chromaffin tissue consists of 82.9±2.6% of A and 17.1±2.6% of NA cells. Cords of the chromaffinocytes run along the nerves in the adrenal cortex and form cones when merging with medulla bulk. There is no unambiguously greater prevalence of A cells over NA in the areas of the medulla bordering on the cortex as compared to deep layers of medulla. NA cells form a network of beams. Their concentration increases with distance from the entry site of the nerves and is maximal on the opposite side. This testifies to the fallacy of the point of view about the disordered distribution of NA cells in the medulla. Based on the polar asymmetric arrangement of the adrenal chromaffin tissue, if it is necessary to completely remove the medulla with the keeping or reimplantation of the cortex, the subcapsular cortex zone located on the pole opposite to the entrance of nerves should be chosen. In addition, comparable results in the stereological examination of the medulla can be obtained only if taking its areas similar in location. The pronounced relationship in the arrangement of A and NA cells with nerves clearly indicates that in vivo nerve factors play a key role in differentiation and stabilization of the A and NA cells phenotypes.

Renal artery responses to trace amines: Multiple and differential mechanisms of action

PurposeThe rise in consumption of dietary supplements containing the trace amines p-tyramine, p-synephrine and p-octopamine has been associated with cardiovascular side effects. Since renal blood flow plays an important role in blood pressure regulation, this study investigated the mechanisms of action of these trace amines on isolated porcine renal arteries. Main methodsContractile responses to amines were investigated in noradrenaline-depleted rings of porcine main renal arteries in the absence and presence of the α1-adrenoceptor antagonist, prazosin (1 μM), β-adrenoceptor antagonist, propranolol (1 μM), or the trace amine-associated receptor (TAAR-1) antagonist, EPPTB (RO-5212773; 100 nM or 100 μM). Key findingsAll three amines induced constrictor responses of similar magnitude and potency. However, their mechanisms of action on the renal artery appeared to differ. Depleting endogenous noradrenaline stores significantly reduced maximum responses to tyramine and synephrine, but less for octopamine. When direct responses were examined after depleting tissues of noradrenaline, responses to synephrine and octopamine, but not tyramine, were reduced in the presence of prazosin(1 μM) and potentiated in the presence of propranolol (1 μM) or L-NNA (100 μM). Generally, vasoconstrictor responses remaining after noradrenaline-depletion and α-adrenoceptor blockade were not affected by the TAAR-1 antagonist EPPTB (0.1–100 μM), although responses to low concentration of synephrine and octopamine were enhanced by this antagonist. SignificanceTyramine appears to mediate constriction of the renal artery mainly via an indirect sympathomimetic mechanism, whereas synephrine and octopamine exert additional direct effects on α1-adrenoceptors and possibly contractile TAAR (not TAAR-1). The two amines also activate simultaneous inhibitory responses via β-adrenoceptors, TAAR-1 and nitric oxide release.

Computational modeling reveals multiple abnormalities of myocardial noradrenergic function in Lewy body diseases.

Lewy body diseases, a family of aging-related neurodegenerative disorders, entail loss of the catecholamine dopamine in the nigrostriatal system and equally severe deficiency of the closely related catecholamine norepinephrine in the heart. The myocardial noradrenergic lesion is associated with major non-motor symptoms and decreased survival. Numerous mechanisms determine norepinephrine stores, and which of these are altered in Lewy body diseases has not been examined in an integrated way. We used a computational modeling approach to assess comprehensively pathways of cardiac norepinephrine synthesis, storage, release, reuptake, and metabolism in Lewy body diseases. Application of a novel kinetic model identified a pattern of dysfunctional steps contributing to norepinephrine deficiency. We then tested predictions from the model in a new cohort of Parkinson disease patients. Rate constants were calculated for 17 reactions determining intra-neuronal norepinephrine stores. Model predictions were tested by measuring post-mortem apical ventricular concentrations and concentration ratios of catechols in controls and patients with Parkinson disease. The model identified low rate constants for three types of processes in the Lewy body group-catecholamine biosynthesis via tyrosine hydroxylase and L-aromatic-amino-acid decarboxylase, vesicular storage of dopamine and norepinephrine, and neuronal norepinephrine reuptake via the cell membrane norepinephrine transporter. Post-mortem catechols and catechol ratios confirmed this triad of model-predicted functional abnormalities. Denervation-independent impairments of neurotransmitter biosynthesis, vesicular sequestration, and norepinephrine recycling contribute to the myocardial norepinephrine deficiency attending Lewy body diseases. A proportion of cardiac sympathetic nerves are "sick but not dead," suggesting targeted disease-modification strategies might retard clinical progression. This study was not a clinical trial. The research reported here was supported by the Division of Intramural Research, NINDS.

Melatonin treatment affects changes in adrenal gene expression of catecholamine biosynthesizing enzymes and norepinephrine transporter in the rat model of chronic-stress-induced depression.

This study investigated the effects of melatonin treatment on adrenal catecholamine content, synthesis, uptake, and vesicular transport induced by the chronic unpredictable mild stress (CUMS) model of depression in rats. This entailed quantifying the norepinephrine, epinephrine, mRNA, and protein levels of tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), norepinephrine transporter (NET), and vesicular monoamine transporter 2 (VMAT2) in the adrenal medulla. CUMS caused a significant depletion of norepinephrine stores and protein levels of TH, DBH, and NET, whereas the gene expression of PNMT was increased. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in norepinephrine content and the protein expression of TH, DBH, and NET in the adrenal medulla of chronically stressed rats. The present study demonstrates the stimulatory effect of melatonin on adrenomedullary synthesis, the uptake and content of catecholamine in the rat model of chronic stress-induced depression.

Perivascular Adipocytes Store Norepinephrine by Vesicular Transport.

Objective- Perivascular adipose tissue (PVAT) contains an independent adrenergic system that can take up, metabolize, release, and potentially synthesize the vasoactive catecholamine norepinephrine. Norepinephrine has been detected in PVAT, but the mechanism of its protection within this tissue is unknown. Here, we investigate whether PVAT adipocytes can store norepinephrine using VMAT (vesicular monoamine transporter). Approach and Results- High-performance liquid chromatography identified norepinephrine in normal male Sprague Dawley rat aortic, superior mesenteric artery, and mesenteric resistance vessel PVATs, and retroperitoneal fat. Real-time polymerase chain reaction revealed VMAT1 and VMAT2 mRNA expression in the adipocytes and stromal vascular fraction of mesenteric resistance vessel PVAT. Immunofluorescence demonstrated the presence of VMAT1 and VMAT2, and the colocalization of VMAT2 with norepinephrine, in the cytoplasm of adipocytes in mesenteric resistance vessel PVAT. A protocol was developed to capture real-time uptake of Mini 202-a functional and fluorescent VMAT probe-in live rat PVAT adipocytes. Mini 202 was taken up by freshly isolated and differentiated adipocytes from mesenteric resistance vessel PVAT and adipocytes from thoracic aortic and superior mesenteric artery PVATs. In adipocytes freshly isolated from mesenteric resistance vessel PVAT, addition of rose bengal (VMAT inhibitor), nisoxetine (norepinephrine transporter inhibitor), or corticosterone (organic cation 3 transporter inhibitor) significantly reduced Mini 202 signal. Immunofluorescence supports that neither VMAT1 nor VMAT2 is present in retroperitoneal adipocytes, suggesting that PVAT adipocytes may be unique in storing norepinephrine. Conclusions- This study supports a novel function of PVAT adipocytes in storing amines in a VMAT-dependent manner. It provides a foundation for future studies exploring the purpose and mechanisms of norepinephrine storage by PVAT in normal physiology and obesity-related hypertension.

'Sick But Not Dead': Multiple Denervation-Independent Abnormalities of Myocardial Noradrenergic Function in Lewy Body Diseases

Background: Lewy body diseases such as Parkinson disease (PD) are well known to be characterized by nigrostriatal dopamine deficiency. These disorders also entail drastic (95-99%) myocardial depletion of the sympathetic neurotransmitter norepinephrine. Catecholamine loss in both regions cannot be accounted for by denervation alone. We evaluated the possibility of decreased innervation combined with functional abnormalities in residual nerves, using previously published data and a novel, comprehensive kinetic model. We then tested predictions from the model in new subject cohorts. Methods: We calculated rate constants for 17 reactions related to myocardial intra-neuronal norepinephrine synthesis, storage, and disposition in control subjects and patients with Lewy body diseases. Post-mortem apical ventricular concentrations and concentration ratios of catechols were used to test predictions from the model in 11 controls and 11 patients with autopsy-proven PD. Results: Calculated rate constants for vesicular storage of dopamine and norepinephrine, catecholamine biosynthesis via tyrosine hydroxylase and L-aromatic-amino-acid decarboxylase, and neuronal norepinephrine reuptake via the cell membrane norepinephrine transporter were reduced in the Lewy body group. In PD myocardial norepinephrine content was decreased by 99% from controls (p<0.0001). Post-mortem catechols and catechol ratios in PD patients confirmed the pattern of model-predicted functional abnormalities. Conclusions: Denervation-independent impaired neurotransmitter biosynthesis, vesicular sequestration, and norepinephrine recycling via neuronal reuptake contribute importantly to the myocardial norepinephrine deficiency attending Lewy body diseases. The finding that a substantial proportion of catecholaminergic neurons are sick but not dead offers new hope for disease-modification strategies that might slow or prevent progression of this family of neurodegenerative disorders. Funding: The research reported here was supported by the Division of Intramural Research, NINDS. Declaration of Interest: The Authors have no conflicts of interest to disclose. Ethical Approval: For all the subjects, written informed consent was obtained prior to participation in protocols approved by the Institutional Review Board of the National Institute of Neurological Disorders and Stroke, or else the next of kin gave written informed consent for post-mortem tissue harvesting for research purposes.

VNUT and VMAT2 segregate within sympathetic varicosities and localize near preferred Cav2 isoforms in the rat tail artery.

ATP and norepinephrine (NE) are coreleased from peripheral sympathetic nerve terminals. Whether they are stored in the same vesicles has been debated for decades. Preferential dependence of NE or ATP release on Ca2+ influx through specific voltage-gated Ca2+ channel (Cav2) isoforms suggests that NE and ATP are stored in separate vesicle pools, but simultaneous imaging of NE and ATP containing vesicles within single varicosities has not been reported. We conducted an immunohistochemical study of vesicular monoamine transporter 2 (VMAT2/SLC18A2) and vesicular nucleotide translocase (VNUT/SLC17A9) as markers of vesicles containing NE and ATP in sympathetic nerves of the rat tail artery. A large fraction of varicosities exhibited neighboring, rather than overlapping, VNUT and VMAT2 fluorescent puncta. VMAT2, but not VNUT, colocalized with synaptotagmin 1. Cav2.1, Cav2.2, and Cav2.3 are expressed in nerves in the tunica adventitia. VMAT2 preferentially localized adjacent to Cav2.2 and Cav2.3 rather than Cav2.1. VNUT preferentially localized adjacent to Cav2.3 > Cav2.2 >> Cav2.1. With the use of wire myography, inhibition of field-stimulated vasoconstriction with the Cav2.3 blocker SNX-482 (0.25 µM) mimicked the effects of the P2X inhibitor suramin (100 µM) rather than the α-adrenergic inhibitor phentolamine (10 µM). Variable sensitivity to SNX-482 and suramin between animals closely correlated with Cav2.3 staining. We concluded that a majority of ATP and NE stores localize to separate vesicle pools that use different synaptotagmin isoforms and that localize near different Cav2 isoforms to mediate vesicle release. Cav2.3 appears to play a previously unrecognized role in mediating ATP release in the rat tail artery. NEW & NOTEWORTHY Immunofluorescence imaging of vesicular nucleotide translocase and vesicular monoamine transporter 2 in rat tail arteries revealed that ATP and norepinephrine, classical cotransmitters, localize to well-segregated vesicle pools. Furthermore, vesicular nucleotide translocase and vesicular monoamine transporter 2 exhibit preferential localization with specific Cav2 isoforms. These novel observations address long-standing debates regarding the mechanism(s) of sympathetic neurotransmitter corelease.

Perivascular Adipocytes Store Norepinephrine by Vesicular Transport

Perivascular adipose tissue (PVAT) exerts an anti‐contractile effect on blood vessels in healthy individuals, a mechanism lost in obesity‐related hypertension. To understand this process, we must first investigate the role of the functional adrenergic system residing within PVAT. We have shown that PVAT contains functional norepinephrine (NE), and that PVAT adipocytes have NE transporters, similar to sympathetic neurons. We hypothesize that NE is stored in vesicles within PVAT adipocytes, and that the vesicular monoamine transporter (VMAT) is used to do so. High‐performance liquid chromatography showed the presence of NE in normal male Sprague Dawley rat superior mesenteric artery (SMPVAT; 503.60 ± 34.70 ng/g tissue) and mesenteric (MPVAT; 148.20 ± 15.00 ng/g tissue) PVATs (N=6). Using immunofluorescence, we tested for VMAT1 and VMAT2 in these PVATs (N=6), and both transporters were present surrounding the lipid of the adipocytes. Immunofluorescence of MPVAT (N=4) and SMPVAT (N=4) revealed the co‐localization of NE and VMAT2 surrounding the lipid of PVAT adipocytes, and especially concentrated around the nucleus. We developed a protocol imaging live primary rat MPVAT adipocytes to capture real‐time uptake of Mini202, a fluorescent VMAT probe functioning as a false neurotransmitter (N=4). Cells were stained with 500 μM Mini202 (see data table). Addition of Rose Bengal (100 μM), a potent VMAT inhibitor, significantly reduced Mini202 signal. Addition of plasma membrane transporter inhibitors, nisoxetine (NE transporter, 10 mM) and corticosterone (organic cation 3 transporter, 10 mM) also significantly reduced Mini202 signal. Interestingly, immunofluorescence results support that neither VMAT1 (N=4) nor VMAT2 (N=4) is present in retroperitoneal adipocytes, suggesting that perivascular adipocytes are unique in their ability to store NE. This study supports a new function of perivascular adipocytes in storing amines and provides a basis for understanding NE storage by PVAT in obesity‐related hypertension.Support or Funding InformationFunding provided by NIH NHLBI PO1HL70687 and the APS UGREFThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Depletion of cardiac catecholamine stores impairs cardiac norepinephrine re-uptake by downregulation of the norepinephrine transporter.

In heart failure (HF), a disturbed cardiac norepinephrine (NE) homeostasis is characterized by depleted cardiac NE stores, impairment of the cardiac NE re-uptake by the neuronal norepinephrine transporter (NET) and enhanced cardiac NE net release. Reduced cardiac NE content appears to be caused by enhanced cardiac NE net release from sympathetic neurons in HF, triggered by neurohumoral activation. However, it remains unclear whether reduced NE itself has an impact on cardiac NE re-uptake, independent of neurohumoral activation. Here, we evaluated whether depletion of cardiac NE stores alone can regulate cardiac NE re-uptake. Treatment of Wistar rats with reserpine (5 mg/kg/d) for one (1d) or five days (5d) resulted in markedly reduced cardiac NE content, comparable to NE stores in experimental HF due to pressure overload. In order to assess cardiac NE re-uptake, the specific cardiac [3H]-NE uptake via the NET in a Langendorff preparation was measured. Reserpine treatment led to decreased NE re-uptake at 1d and 5d compared to saline treatment. Expression of tyrosine hydroxylase (TH), the rate-limiting enzyme of the NE synthesis, was elevated in left stellate ganglia after reserpine. Mechanistically, measurement of NET mRNA expression in left stellate ganglia and myocardial NET density revealed a post-transcriptional downregulation of the NET by reserpine. In summary, present data demonstrate that depletion of cardiac NE stores alone is sufficient to impair cardiac NE re-uptake via downregulation of the NET, independent of systemic neurohumoral activation. Knowledge about the regulation of the cardiac NE homeostasis may offer novel therapeutic strategies in HF.

Melatonin mediated antidepressant-like effect in the hippocampus of chronic stress-induced depression rats: Regulating vesicular monoamine transporter 2 and monoamine oxidase A levels

The hippocampus is sensitive to stress which activates norepinephrine terminals deriving from the locus coeruleus. Melatonin exerts positive effects on the hippocampal neurogenic process and on depressive-like behaviour. Thus, in the present study, an examination was made of the effect of chronic melatonin treatment on norepinephrine content, synthesis, uptake, vesicular transport and degradation in the hippocampus of rats exposed to CUMS. This entailed quantifying the norephinephrine, mRNA and protein levels of DBH, NET, VMAT 2, MAO-A and COMT. The results show that CUMS evoked prolonged immobility. Melatonin treatment decreased immobility in comparison with the placebo group, reflecting an antidepressant-like effect. Compared with the placebo group, a dramatic decrease in norepinephrine content, decreased VMAT2 mRNA and protein and increased MAO-A protein levels in the hippocampus of the CUMS rats were observed. However, no significant differences in the levels of DBH, NET, COMT mRNA and protein and MAO-A mRNA levels between the placebo and the stressed groups were found. The results showed the restorative effects of melatonin on the stress-induced decline in the norepinephrine content of the hippocampus. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in VMAT2 mRNA and protein levels, whereas it reduced the increase of the mRNA of COMT and protein levels of MAO-A. Chronic treatment with melatonin failed to alter the gene expression of DBH or NET in the hippocampus of the CUMS rats. Additionally, the results show that melatonin enhances VMAT2 expression and norepinephrine storage, whilst it reduces norepinephrine degrading enzymes.

Experimental diabetic diarrhea in rats. Intestinal mucosal denervation hypersensitivity and treatment with clonidine.

Diarrhea in streptozocin-induced chronically diabetic rats is caused by an impaired adrenergic regulation of intestinal fluid and electrolyte transport. Stimulation of alpha 2-adrenergic receptors on enterocytes normally promotes NaCl absorption and inhibits HCO3 secretion. The purpose of this study was to determine if adrenergic denervation of intestinal mucosa in chronically diabetic rats alters postsynaptic receptor response, and if the alpha 2-adrenergic agonist clonidine could correct observed fluid malabsorption. Mucosal norepinephrine stores, a measure of adrenergic tone, were markedly reduced in diabetic rats compared with nondiabetic littermates. In vitro, short-circuit current changes to exogenously added l-epinephrine were significantly greater in diabetics, suggesting that denervation hypersensitivity was due to increased numbers of postsynaptic alpha 2-adrenergic receptors. In vivo loop studies demonstrated net fluid secretion in the ileum and colon of diabetics. In diabetics, clonidine reversed the secretion to absorption, but it had no effect on fluid absorption in controls. We conclude that diabetic diarrhea in streptozocin-induced chronically diabetic rats is due to impaired adrenergic regulation of mucosal ion transport, accompanied by a postsynaptic denervation hypersensitivity that can be reversed by clonidine, and accompanied by net intestinal fluid secretion that can be effectively reversed with clonidine.

Frequency of Perceived Poststress Symptoms in Inpatients, Outpatients and Healthy Controls: The Role of Perceived Exhaustion and Stress

Background: Poststress symptoms occur as a consequence of stress, most commonly during leisure periods such as weekends and vacations. However, the prevalence and the pathological mechanisms of poststress symptoms are poorly understood. Methods: Here, we compared the frequency of poststress symptoms in healthy controls (n = 984), outpatients (n = 420), and inpatients (n = 101). In outpatients, demographic factors, psychosocial stress, and perceived exhaustion were tested as predictors of poststress symptoms with multivariate regression analysis. Poststress symptoms and perceived exhaustion were assessed using 2 Neuropattern Questionnaires (the NPQ - Patient Questionnaire and the NPQ - Symptom List), and psychosocial stress was evaluated using the Patient Health Questionnaire (PHQ). Results: Poststress symptoms appeared in 2.9% of healthy controls, 20.0% of outpatients, and 34.7% of inpatients. Predictors were educational level, psychosocial stress, and perceived exhaustion. Poststress symptoms differed primarily between exhausted (75.0%) and nonexhausted patients (25.0%). Conclusion: Poststress symptoms are rather common in clinical populations, and they are primarily associated with the degree of perceived exhaustion. Preliminary evidence suggests that poststress symptoms are possibly related to depletion of norepinephrine stores, which may facilitate a stratified preventive and therapeutic treatment of these subjects.

Natural Diterpenes from Coffee, Cafestol, and Kahweol Induce Peripheral Antinoceception by Adrenergic System Interaction.

Cafestol and kahweol are diterpenes found only in the non-saponified lipid fraction of coffee. They are released during boiling and retained in the filtration process. Previous studies have shown peripheral antinociception induced by endogenous opioid peptides released by these diterpenes. Considering that the activation of the opioid system leads to a noradrenaline release, the aim of this study was to verify the participation of the noradrenergic system in the peripheral antinociception induced by cafestol and kahweol. Hyperalgesia was induced by an intraplantar injection of prostaglandin E2 (2 µg). Cafestol or kahweol (80 µg/paw) were administered locally into the right hindpaw alone, and after the agents α 2-adrenoceptor antagonist yohimbine (5, 10 and 20 µg/paw), α 2 A-adrenoceptor antagonist BRL 44 408 (40 µg/paw), α 2B-adrenoceptor antagonist imiloxan (40 µg/paw), α 2 C-adrenoceptor antagonist rauwolscine (10, 15 and 20 µg/paw), α 2D-adrenoceptor antagonist RX 821 002 (40 µg/paw), α 1-adrenoceptor antagonist prazosin (0.5, 1 and 2 µg/paw), or β-adrenoceptor antagonist propranolol (150, 300 and 600 ng/paw), respectively. Noradrenaline reuptake inhibitor reboxetine (30 µg/paw) was administered prior to cafestol or kahweol low dose (40 µg/paw) and guanetidine 3 days prior to the experiment (30 mg/kg, once a day), depleting the noradrenaline storage. Intraplantar injection of cafestol or kahweol (80 µg/paw) induced a peripheral antinociception against hyperalgesia induced by PGE2. This effect was reversed by intraplantar injections of yohimbine, rauwolscine, prazosin and propranolol. Reboxetine injection intensified the antinociceptive effect of cafestol or kahweol low-dose, and guanethidine reversed almost 70 % of the cafestol or kahweol-induced peripheral antinociception. This study gives evidence that the noradrenergic system participates in cafestol and kahweol-induced peripheral antinociception with the release of endogenous noradrenaline.

Influence of individual housing in the adult rats on catecholamine synthesis and storage in the right and left medial prefrontal cortex

Social isolation produce various neurochemical alterations in monoamines pathways of the brain. In order to assess the effect of individual housing of adult rats on neurochemical substrates and lateralization in the right and left medial prefrontal cortex (mPFC), we measured dopamine and noradrenaline stores, protein levels of tyrosine-hydroxylase (TH), noradrenaline transporter (NET) and vesicular monoamine transporter 2 (VMAT 2), by Western blot analysis. Individual housing produced no significant changes in dopamine and noradrenaline content, whereas levels of TH and NET were elevated in the right and left mPFC. On the other hand, VMAT 2 protein was reduced in the right mPFC and increased in the left mPFC. The results indicate an increased synthetic and reuptake capacity of noradrenergic terminals in the right and left mPFC and decreased translocation monoamines from the cytoplasm into the intracellular storage vesicles of neurons in the right mPFC.

EHMTI-0360. Chronic sympathetic activation in migraine headache: unique to migraine or common to sympathetic nervous system disorders?

The mechanisms of autonomic nervous system dysfunction in migraine are not well understood. It has been proposed that chronic/excessive SNS activation contributes to migraine episodes by rapidly depleting norepinephrine stores while increasing the release of dopamine, adenosine triphosphate, adenosine and prostaglandins. Research showing significantly colder hands in female migraineurs than healthy controls between headaches suggests evidence of chronic/excessive SNS activation in female migraineurs. A recent audit of standardized clinical assessment data collected over several years during a 26 minute psychophysiological mental stress assessment revealed interesting results which shed light on this dilemma. Data included hand skin temperature (HST), frontal sEMG, HR, SCR, respiration rate and the Anxiety Sensitivity Index. Ten female migraineurs (MH), 10 females with muscle contraction headache (MCH) and 10 females with panic disorder (PD) were compared. MCH controlled for the effects of having a distressing non-migraine/non SNS headache disorder. PD controlled for the effects of having a distressing non-headache, SNS disorder. There were no significant between-group differences for age and most test scores. A repeated measures ANOVA showed a significant between-groups difference for HST. The MCH group was in the normal range while the MH and PD groups were well below normal and significantly colder than the MCH group. The MH group results suggest chronic SNS arousal. However the PD group's similar result and the MCH normal result suggests that chronic SNS arousal is a characteristic of SNS disorders and is not unique to migraine. Alone, it appears insufficient to explain migraine episodes. Additional factors are proposed. No conflict of interest.

Molecular basis of chronic stress-induced hippocampal lateral asymmetry in rats and impact on learning and memory

Neurochemical lateralization has been demonstrated in the rat brain suggesting that such lateralization might contribute to behavior. Thus, the aim of the present study was to examine neurochemical asymmetry in the hippocampus, molecular basis of neurochemical lateralization and its impact on spatial learning and memory. Changes in noradrenaline content, tyrosine hydroxylase (TH) were studied in the right and left hippocampus of naive control and chronically isolated rats, by applying TaqMan RT-PCR and Western blot analysis. Hippocampal-based spatial learning and memory were evaluated using the Barnes maze. In control rats an asymmetrical right-left distribution of noradrenaline content and gene expression of catecholamine synthesizing enzyme was found. Chronic psychosocial stress further emphasized asymmetry. Isolation stress reduced noradrenaline content only in the right hippocampus. No changes were observed in gene expression and protein levels of TH in the right hippocampus, whereas expression of catecholamine synthesizing enzyme was elevated in the left hippocampus. Reduced noradrenaline content in the right hippocampus did not cause impairment in spatial learning and memory. Our findings suggest that chronic psychosocial stress reduces noradrenaline stores in the right hippocampus which may be caused by molecular asymmetry, but it does not affect spatial learning and memory.