Abuse-like toluene exposure during early adolescence alters subsequent ethanol and cocaine behavioral effects and brain monoamines in male mice.

Currently, there is a gap in understanding the neurobiological impact early adolescent toluene exposure has on subsequent actions of other drugs. Adolescent (PND 28-32) male Swiss-Webster mice (N = 210) were exposed to 0, 2000, or 4000 ppm of toluene vapor for 30 min/day for 5 days. Immediately following the last toluene exposure (PND 32; n = 15) or after a short delay (PND 35; n = 15), a subset of subjects' brains was collected for monoamine analysis. Remaining mice were assigned to one of two abstinence periods: a short 4-day (PND 36) or long 12-day (PND 44) delay after toluene exposure. Mice were then subjected to a cumulative dose response assessment of either cocaine (0, 2.5, 5, 10, 20 mg/kg; n = 60), ethanol (0, 0.5, 1, 2, 4 g/kg; n = 60), or saline (5 control injections; n = 60). Toluene concentration-dependently increased locomotor activity during exposure. When later challenged, mice exposed previously to toluene were significantly less active after cocaine (10 and 20 mg/kg) compared to air-exposed controls. Animals were also less active at the highest dose of alcohol (4 g/kg) following prior exposure to 4000 ppm when compared to air-exposed controls. Analysis of monoamines and their metabolites using High Pressure Liquid Chromatography (HPLC) within the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum (dSTR), and ventral tegmental area (VTA) revealed subtle effects on monoamine or metabolite levels following cumulative dosing that varied by drug (cocaine and ethanol) and abstinence duration. Our results suggest that early adolescent toluene exposure produces behavioral desensitization to subsequent cocaine-induced locomotor activity with subtle enhancement of ethanol's depressive effects and less clear impacts on levels of monoamines.

Interactive effects of cyanobacterial metabolites aeruginosin-98B, anabaenopeptin-B and cylindrospermopsin on physiological parameters and novel in vivo fluorescent indicators in Chironomus aprilinus larvae.

We aimed to determine the effects of single cyanobacterial metabolites aeruginosin-B (AER-B), anabaenopeptin-B (ANA-B), cylindrospermopsin (CYL), their binary and ternary mixtures on biomarkers of Chironomus aprilinus larvae: oxygen consumption, fat body structure and two novel fluorescent indicators: imaging of nuclei in cells of body integument, and the catecholamine level. The obtained results showed that oxygen consumption was inhibited by single tested cyanobacterial metabolites except for ANA-B at the lowest concentration (250 µg/L). Although the mixtures of the metabolites inhibited oxygen consumption with antagonistic interactions between the components stimulation was noted in the group exposed to the lowest concentrations of AER-B + CYL (125 µg/L + 125 µg/L, respectively) and the ternary mixture of AER-B + ANA-B + CYL (83.3 µg/L + 83.3 µg/L + 83.3 µg/L, respectively). In vivo fluorescent staining with Hoechst 34580 showed that single AER-B had lower cytotoxic potential on body integument cells than ANA-B and CYL and most binary mixtures except for AER-B + CYL induced synergistic toxicity. Catecholamine level was decreased in animals exposed to single metabolites, their binary and ternary mixtures; however, the interactions between the components in the ternary mixture were antagonistic. Fat body was found to be disrupted in the larvae exposed to single metabolites and their combinations. Antagonistic toxic interactions between the oligopeptide components were found in most binary and the ternary mixtures; however, synergistic effect was noted in the binary mixture of AER-B + CYL. The results suggest that in natural conditions Chironomus larvae and possibly other benthic invertebrates may be affected by cyanobacterial metabolites, however various components and in mixtures and their concentrations may determine varied physiological effects and diverse interactions.

Effect of propranolol on temporomandibular joint pain in repeatedly stressed rats.

Stress substantially increases the risk of developing painful temporomandibular disorders (TMDs) by influencing the release of endogenous catecholamines. Propranolol, an antagonist of ß-adrenergic receptors, has shown potential in alleviating TMD-associated pain, particularly when the level of catecholamines is elevated. The aim of this study was to explore whether intra-articular propranolol administration is effective in diminishing temporomandibular joint (TMJ) pain during repeated stress situations. Additionally, we investigated the effect of repeated stress on the expression of genes encoding ß-adrenoceptors in the trigeminal ganglion. In the present study, rats were exposed to a stress protocol induced by sound, then to the administration of formalin in the TMJ (to elicit a nociceptive response), followed immediately afterward by different doses of propranolol, after which the analgesic response to propranolol was evaluated. We also assessed the levels of beta-1 and beta-2 adrenergic receptor mRNAs (Adrb1 and Adrb2, respectively) using reverse transcription-quantitative PCR (RT-qPCR). Our findings revealed that propranolol administration reduces formalin-induced TMJ nociception more effectively in stressed rats than in non-stressed rats. Furthermore, repeated stress decreases the expression of the Adrb2 gene within the trigeminal ganglion. The findings of this study are noteworthy as they suggest that individuals with a chronic stress history might find potential benefits from ß-blockers in TMD treatment.

Platelet-inspired synthetic nanoparticles improve hemostasis and hemodynamics in a rabbit model of abdominal hemorrhage.

BACKGROUND: Early platelet transfusion is associated with reduced mortality in traumatic hemorrhage. However, platelet usage is severely limited because of the challenges of donor availability, platelet portability, and storage. Here, we report on a bioinspired synthetic platelet (SP) nanoconstruct that utilizes liposome surface-decoration with peptides that mimic injury site-specific platelet adhesion to von Willebrand Factor and collagen, and fibrinogen-mediated platelet aggregation. Synthetic platelet has previously shown promising hemostatic outcomes in vitro and in vivo. Here, we evaluated hemostasis and hemodynamic effects of SP in a rabbit model of abdominal hemorrhage. METHODS: Twenty-three adult male New Zealand white rabbits (2.5-3.5 kg) were treated with either buffer, control particles (CPs), or SP. Under general anesthesia with invasive monitoring, rabbits underwent laparotomy with combined splenic and hepatic injury. Hemodynamics were monitored for 30 minutes and blood loss was quantified. Blood counts, aggregometry, catecholamine and platelet factor 4 (PF4) assays were performed at multiple timepoints. Analysis used analysis of variance and post hoc Tukey testing with α = 0.05. RESULTS: Rabbits in the SP (n = 7) group had significantly lower weight-normalized blood loss compared with both buffer (n = 8) and CP (n = 8) animals (21.1 vs. 33.2 vs. 40.4 g/kg, p < 0.001). Synthetic platelet-treated animals had higher systolic blood pressure area under curve compared with buffer- and CP-treated animals (1567 vs. 1281 vs. 1109 mm Hg*min, p = 0.006), although post hoc differences were only significant for the SP/CP comparison ( p = 0.005). Platelet counts, catecholamine levels, PF4, and aggregometry were similar between groups. CONCLUSION: Synthetic platelet treatment significantly reduced blood loss and improved hemodynamics in a rabbit abdominal hemorrhage model. Synthetic platelet has potential as an intravenous hemostatic platelet surrogate with donor-independent availability and scalable manufacture.

Effects of Catecholamine Stress Hormones Norepinephrine and Epinephrine on Growth, Antimicrobial Susceptibility, Biofilm Formation, and Gene Expressions of Enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) is a significant contributor to diarrhea. To determine whether ETEC-catecholamine hormone interactions contribute to the development of diarrhea, we tested the effects of catecholamine hormones acting on ETEC in vitro. The results showed that in the presence of norepinephrine (NE) and epinephrine (Epi), the growth of 9 out of 10 ETEC isolates was promoted, the MICs of more than 60% of the isolates to 6 antibiotics significantly increased, and the biofilm formation ability of 10 ETEC isolates was also promoted. In addition, NE and Epi also significantly upregulated the expression of the virulence genes feaG, estA, estB, and elt. Transcriptome analysis revealed that the expression of 290 genes was affected by NE. These data demonstrated that catecholamine hormones may augment the diarrhea caused by ETEC.

Increased OCT3 Expression in Adipose Tissue With Aging: Implications for Catecholamine and Lipid Turnover and Insulin Resistance in Women.

BACKGROUND: Catecholamine-stimulated lipolysis is reduced with aging, which may promote adiposity and insulin resistance. Organic cation transporter 3 (OCT3), which is inhibited by estradiol (E2), mediates catecholamine transport into adipocytes for degradation, thus decreasing lipolysis. In this study, we investigated the association of OCT3 mRNA levels in subcutaneous adipose tissue (SAT) with aging and markers of insulin resistance in women. METHODS: SAT biopsies were obtained from 66 women with (19) or without (47) type 2 diabetes (age 22-76 years, 20.0-40.1 kg/m2). OCT3 mRNA and protein levels were measured for group comparisons and correlation analysis. SAT was incubated with E2 and OCT3 mRNA levels were measured. Associations between OCT3 single nucleotide polymorphisms (SNPs) and diabetes-associated traits were assessed. RESULTS: OCT3 mRNA and protein levels in SAT increased with aging. SAT from postmenopausal women had higher levels of OCT3 than premenopausal women, and there was a dose-dependent reduction in OCT3 mRNA levels in SAT treated with E2. OCT3 mRNA levels were negatively associated with markers of insulin resistance, and ex vivo lipolysis. OCT3 SNPs were associated with BMI, waist to hip ratio, and circulating lipids (eg, triglycerides). CONCLUSION: OCT3 mRNA and protein levels in SAT increased with aging, and mRNA levels were negatively associated with markers of insulin resistance. E2 incubation downregulated OCT3 mRNA levels, which may explain lower OCT3 mRNA in premenopausal vs postmenopausal women. High OCT3 protein levels in adipose tissue may result in increased catecholamine degradation, and this can contribute to the reduction in lipolysis observed in women with aging.

Inhibition of the mitochondrial respiratory chain reduces catecholamine­stimulated lipolysis via increasing lactate production in 3T3­L1 adipocytes.

Adipose tissue serves a significant role in the regulation of energy metabolism in the body. The re­esterification of the fatty acids generated during lipolysis is critical for efficient lipolysis. However, the effect of the intracellular energy state on lipolytic activity and fatty acid re­esterification during lipolysis is not yet fully understood. The present study aimed to assess the effect of the intracellular energy state on lipolytic activity and fatty acid re­esterification during lipolysis. 3T3­L1 adipocytes were incubated with mitochondrial respiratory chain inhibitors, oligomycin A or rotenone, during isoproterenol stimulation; and glycerol, glucose and lactate concentrations in the medium were measured. Western blot analysis was performed to examine the phosphorylation levels of cAMP­dependent protein kinase A (PKA). The results showed that inhibition of mitochondrial ATP synthesis decreased catecholamine­stimulated lipolysis without affecting PKA signaling. The inhibition of mitochondrial respiration increased glucose uptake and lactate production, indicating that a large amount of glucose taken up into the cell was preferentially used for ATP production rather than for re­esterification. In conclusion, the results of the present study suggested that the energy state during lipolysis may influence lipolytic activity by suppressing fatty acid re­esterification.

Assessment of cardiovascular alterations and catecholamines serum concentration after oral surgery in patients receiving local anesthetics with epinephrine: a randomized, blind, controlled clinical trial.

OBJECTIVES: A randomized controlled clinical trial was developed to evaluate the cardiovascular effects of local anesthetics with vasoconstrictors (LAVC) in healthy and hypertensive patients undergoing teeth extraction with lidocaine 2% with epinephrine 1:100,000. MATERIALS AND METHODS: Twenty patients were divided into control (CG - normotensive patients) and experimental groups (EG - hypertensive patients). The variables analyzed were heart rate (HR), oxygen saturation (SO2), systolic and diastolic blood pressure (SBP and DBP), serum catecholamine concentration (dopamine, epinephrine, and norepinephrine), ventricular and supraventricular extrasystoles (VES and SVES respectively), and ST segment depression. Data was obtained in three different moments (initial, trans, and final). Blood samples were taken to measure the catecholamines, and a Holter device was used to measure data from the electrocardiogram including a 24-h postoperative evaluation period. The Mann-Whitney test was used to identify differences between the two groups, and the Friedman test with the adjusted Wilcoxon posttest was used for intragroup evaluation for repeated measures. RESULTS: The EG presented a lower O2S in the initial period (p = 0,001) while the sysBP showed a statistical difference for the three evaluation periods with the EG presenting the highest values. The VES was higher for the EG during the 24-h postoperative evaluation period (p = 0,041). The SVES and the serum catecholamines showed were similar between the groups. The intragroup analysis revealed significant statistical difference for the sysBP in the EG with the trans period presenting the highest measurements. The extrasystole evaluation showed that the 24-h postoperative period presented most events with only the CG not presenting statistical difference for the variable VES during this period (p = 0,112). No ST segment depression was noticed for both groups. CONCLUSIONS: Teeth extraction with LAVC can be safely executed in hypertensive patients. Blood pressure should be monitored in these patients since the sysBP presented significant differences during the surgical procedures. Cardiac arrhythmia and the serum catecholamines concentration levels seem not to be altered by the surgical procedure. Also, serum catecholamines do not influence cardiovascular changes in this type of surgery. CLINICAL RELEVANCE: LAVC can be safely used in hypertensive patients and does not increase the risk of arrhythmias or cardiac ischemia.

Effects of Catecholamines on Blood Flow in Preterm Infants: A Subanalysis of PICC-MBF Trial.

INTRODUCTION: This study evaluated the correlation between skin blood flow and systemic blood flow and whether skin blood flow can determine the circulatory effects of dopamine and dobutamine on blood flow in very low birth weight (VLBW) infants. METHODS: This study was a subanalysis of the PICC-MBF randomized controlled trial. The correlation between skin blood flow and echocardiographic findings was examined. Changes in skin blood flow and blood pressure before and after initiation or dose increase of dopamine and dobutamine were also evaluated. RESULTS: Two hundred and thirty-four participants underwent echocardiography. Skin blood flow was significantly correlated with supra vena cava (SVC) flow (r = 0.31, p < 0.001). Receiver operator characteristic analysis revealed that skin blood flow <17 mL/min effectively detected SVC flow <41 mL/min (area under the curve = 0.83, p < 0.001). Dobutamine significantly increased skin blood flow after initiation or dose increase (p = 0.033) without increasing blood pressure. However, dopamine significantly increased both skin blood flow (p = 0.010) and blood pressure (p < 0.001). CONCLUSIONS: Our findings indicated that skin blood flow could be used as a surrogate marker of systemic blood flow in VLBW infants and revealed differences in the effects of dopamine and dobutamine on circulation.

HDAC11 inhibition triggers bimodal thermogenic pathways to circumvent adipocyte catecholamine resistance.

Stimulation of adipocyte ß-adrenergic receptors (ß-ARs) induces expression of uncoupling protein 1 (UCP1), promoting nonshivering thermogenesis. Association of ß-ARs with a lysine-myristoylated form of A kinase-anchoring protein 12 (AKAP12, also known as gravin-α) is required for downstream signaling that culminates in UCP1 induction. Conversely, demyristoylation of gravin-α by histone deacetylase 11 (HDAC11) suppresses this pathway. Whether inhibition of HDAC11 in adipocytes is sufficient to drive UCP1 expression independently of ß-ARs is not known. Here, we demonstrate that adipocyte-specific deletion of HDAC11 in mice leads to robust induction of UCP1 in adipose tissue (AT), resulting in increased body temperature. These effects are mimicked by treating mice in vivo or human AT ex vivo with an HDAC11-selective inhibitor, FT895. FT895 triggers biphasic, gravin-α myristoylation-dependent induction of UCP1 protein expression, with a noncanonical acute response that is posttranscriptional and independent of protein kinase A (PKA), and a delayed response requiring PKA activity and new Ucp1 mRNA synthesis. Remarkably, HDAC11 inhibition promotes UCP1 expression even in models of adipocyte catecholamine resistance where ß-AR signaling is blocked. These findings define cell-autonomous, multimodal roles for HDAC11 as a suppressor of thermogenesis, and highlight the potential of inhibiting HDAC11 to therapeutically alter AT phenotype independently of ß-AR stimulation.

Ferroptosis contributes to catecholamine-induced cardiotoxicity and pathological remodeling.

High levels of circulating catecholamines cause cardiac injury, pathological remodeling, and heart failure, but the underlying mechanisms remain elusive. Here we provide both in vitro and in vivo evidence that excessive ß-adrenergic stimulation induces ferroptosis in cardiomyocytes, revealing a novel mechanism for catecholamine-induced cardiotoxicity and remodeling. We found that isoproterenol, a synthetic catecholamine, promoted glutathione depletion and glutathione peroxidase 4 (GPX4) degradation in cardiomyocytes, leading to GPX4 inactivation and enhanced lipid peroxidation. Isoproterenol also promoted heme oxygenase 1 (HO-1) expression by downregulating the transcription suppressor BTB and CNC homology 1 (Bach1), leading to increased labile iron accumulation through heme degradation. Moreover, isoproterenol markedly induced the accumulation of free iron and lipid reactive oxygen species (ROS) in the mitochondria, while targeted inhibition of iron overload and ROS accumulation within mitochondria effectively inhibited ferroptosis in cardiomyocytes. Importantly, isoproterenol administration markedly induced ferroptosis in the myocardium in vivo, associated with elevated non-heme iron accumulation driven by HO-1 upregulation. Strikingly, blockade of ferroptosis with ferrostatin-1 or inhibition of HO-1 activity with zinc protoporphyrin (ZnPP) effectively alleviated cardiac necrosis, pathological remodeling, and heart failure induced by isoproterenol administration. Taken together, our results reveal that catecholamine stimulation primarily induces ferroptotic cell death in cardiomyocyte through GPX4 and Bach1-HO-1 dependent signaling pathways. Targeting ferroptosis may represent a novel therapeutic strategy for catecholamine overload-induced myocardial injury and heart failure.

Hemodynamic parameters in patients undergoing surgery for pheochromocytoma/paraganglioma: a retrospective study.

BACKGROUND: Pheochromocytoma (PHEO) and paraganglioma (PGL) are rare neuroendocrine tumors characterized by hemodynamic instability, caused by the paroxysmal release of catecholamines. Patients may develop cardiovascular complications in the perioperative phase due to the massive release of catecholamines, particularly during anesthetic induction and surgical manipulation of the tumor. The aim of this retrospective study was to evaluate the risk factors involved in perioperative hemodynamic instability in patients who underwent surgery for chromaffin tumors. METHODS: Forty patients (median age 55 [36.50-64.50]) undergone surgery for PHEO/abdominal PGL from January 2011 to December 2016 at the AOU Careggi (Florence, Italy) were retrospectively evaluated. Systolic, diastolic, and mean blood pressure were considered at baseline and during surgery. Patients with blood pressure steadily < 140/90 mmHg before surgery were considered "adequately prepared". A preoperative therapy with doxazosin, a selective alpha-1 blocker, was started in all patients for at least 14 days prior to the surgery. The presence of hemodynamic instability was reported. RESULTS: Comparing males and females, a significant difference in doxazosin daily dose (p = 0.018), systolic blood pressure (p = 0.048), and in the proportion of adequately prepared patients (p = 0.031) emerged. A positive correlation between preoperative daily dose of doxazosin, tumor size (B = 0.60, p < 0.001), and urinary normetanephrine levels (B = 0.64, p < 0.001) was also observed. Hemodynamic instability occurred in 30.0% of patients. The absence of adequate preparation (p = 0.012) before surgery, urinary normetanephrine levels (NMNur p = 0.039), and surgery time (minutes) (p = 0.021) resulted as risk factors of hemodynamic instability in our series. The use of intraoperative drugs was higher in patients with hemodynamic instability (p < 0.001). A pre-surgical SBP level of > 133 mmHg (OR = 6 CI95% 1.37-26.20, p = 0.017) and an intraoperative SBP and MBP levels of > 127 mmHg (OR = 28.80 CI95% 2.23-371.0, p = 0.010) and > 90 mmHg (OR = 18.90 CI95% 1.82-196.0, p = 0.014), respectively, were identified as effective thresholds to recognize patients at higher risk of HI. CONCLUSIONS: A preoperative therapy with alpha-blockers is useful, but not sufficient to avoid surgical risks. Patients with higher pre-surgical levels of NMNur, pre-surgical SBP > 133 mmHg, and/or intraoperative SBP > 127 mmHg and MBP > 90 mmHg, should be carefully monitored. A multidisciplinary approach is indispensable to optimize the management of PHEOs/abdominal PGLs in order to reduce surgical complications.

Relaxation of thoracic aorta and pulmonary artery rings of marmosets (Callithrix spp.) by endothelium-derived 6-nitrodopamine.

6-Nitrodopamine is a novel catecholamine released by vascular tissues, heart, and vas deferens. The aim of this study was to investigate whether 6-nitrodopamine is released from the thoracic aorta and pulmonary artery rings of marmosets (Callithrix spp.) and to evaluate the relaxing and anti-contractile actions of this catecholamine. Release of 6-nitrodopamine, dopamine, noradrenaline, and adrenaline was assessed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The relaxations induced by 6-nitrodopamine and by the selective dopamine D2 receptor antagonist L-741,626 were evaluated on U-46619 (3 nM)-pre-contracted vessels. The effects of 6-nitrodopamine and L-741,626 on the contractions induced by electric-field stimulation (EFS), dopamine, noradrenaline, and adrenaline were also investigated. Both aorta and pulmonary artery rings exhibited endothelium-dependent release of 6-nitrodopamine, which was significantly reduced by the NO synthesis inhibitor L-NAME. Addition of 6-nitrodopamine or L-741,626 caused concentration-dependent relaxations of both vascular tissues, which were almost abolished by endothelium removal, whereas L-NAME and the soluble guanylate cyclase inhibitor ODQ had no effect on 6-nitrodopamine-induced relaxations. Additionally, pre-incubation with 6-nitrodopamine antagonized the dopamine-induced contractions, without affecting the noradrenaline- and adrenaline-induced contractions. Pre-incubation with L-741,626 antagonized the contractions induced by all catecholamines. The EFS-induced contractions were significantly increased by L-NAME, but unaffected by ODQ. Immunohistochemical assays showed no immunostaining of the neural tissue markers S-100 and calretinin in either vascular tissue. The results indicated that 6-nitrodopamine is the major catecholamine released by marmoset vascular tissues, and it acts as a potent and selective antagonist of dopamine D2-like receptors. 6-nitrodopamine release may be the major mechanism by which NO causes vasodilatation.

6-Nitrodopamine potentiates contractions of rat isolated vas deferens induced by noradrenaline, adrenaline, dopamine and electric field stimulation.

6-Nitrodopamine (6-ND) is a novel endogenous catecholamine that is released from the rat isolated vas deferens, and has been characterized as a major modulator of the contractility of rat isolated epididymal vas deferens (RIEVD). Drugs such as tricyclic antidepressants, α1 and ß1ß2 adrenoceptor blockers, act as selective antagonists of the 6-ND receptor in the RIEVD. In the rat isolated atria, 6-ND has a potent positive chronotropic action and causes remarkable potentiation of the positive chronotropic effects induced by dopamine, noradrenaline, and adrenaline. Here, whether 6-ND interacts with the classical catecholamines in the rat isolated vas deferens was investigated. Incubation with 6-ND (0.1 and 1 nM; 30min) caused no contractions in the RIEVD but provoked significant leftward shifts in the concentration-response curves to noradrenaline, adrenaline, and dopamine. Pre-incubation of the RIEVD with 6-ND (1 nM), potentiated the contractions induced by electric-field stimulation (EFS), whereas pre-incubation with 1 nM of dopamine, noradrenaline or adrenaline, did not affect EFS-induced contractions. In tetrodotoxin (1 µM) pre-treated (30 min) RIEVD, pre-incubation with 6-ND (0.1 nM) did not cause leftward shifts in the concentration-dependent contractions induced by noradrenaline, adrenaline, or dopamine. Pre-incubation of the RIEVD with the α2A-adrenoceptor antagonist idazoxan (30 min, 10 nM) did not affect dopamine, noradrenaline, adrenaline, and EFS-induced contractions. However, when idazoxan (10 nM) and 6-ND (0.1 nM) were simultaneously pre-incubated (30 min), a significant potentiation of the EFS-induced contractions of the RIEVD was observed. 6-nitrodopamine causes remarkable potentiation of dopamine, noradrenaline, and adrenaline contractions on the RIEVD, due to activation of adrenergic terminals, possibly via pre-synaptic adrenoceptors.

Phospholipase C-ε defines a PACAP-stimulated pathway for secretion in the chromaffin cell.

Adrenomedullary chromaffin cells respond to splanchnic (sympathetic) nerve stimulation by releasing stress hormones into the circulation. The signal for hormone secretion is encoded in the neurotransmitters - especially acetylcholine (ACh) and pituitary adenylate cyclase activating polypeptide (PACAP) - that are released into the splanchnic-chromaffin cell synapse. However, functional differences in the effects of ACh and PACAP on the chromaffin cell secretory response are not well defined. Here, selective agonists of PACAP receptors or nicotinic and muscarinic acetylcholine receptors were applied to chromaffin cells. The major differences in the effects of these agents were not on exocytosis, per se, but rather on the steps upstream of exocytosis. In almost every respect, the properties of individual fusion events triggered by PACAP and cholinergic agonists were similar. On the other hand, the properties of the Ca2+ transients evoked by PACAP differed in several ways from those evoked by muscarinic and nicotinic receptor stimulation. A defining feature of the PACAP-stimulated secretory pathway was its dependence on signaling through exchange protein directly activated by cAMP (Epac) and PLCε. However, the absence of PLCε did not disrupt Ca2+ transients evoked by cholinergic agonists. Accordingly, inhibition of Epac activity did not disrupt secretion triggered by acetylcholine or specific agonists of muscarinic and nicotinic receptors. Thus, PACAP and acetylcholine stimulate chromaffin cell secretion via separate and independent pathways. This feature of stimulus-secretion coupling may be important for sustaining hormone release from the adrenal medulla under conditions associated with the sympathetic stress response.

Catecholamines modulate differentially nonapeptide precursor mRNA expression in the preoptic area and ovary of the catfish Heteropneustes fossilis: An in vitro study.

In the catfish Heteropneustes fossilis, three nonapeptide hormone genes were identified in the brain preoptic area (POA) and ovary: a pro-vasotocin (pro-vt) and two isotocin gene paralogs viz., a novel pro-ita and conventional pro-itb. In the present study, the regulatory role of catecholamines [CA: dopamine (DA), noradrenaline (NA), adrenaline (AD)] on the expression of these genes were investigated in vitro. DA (1, 10, and 100 ng/mL) inhibited significantly the mRNA expression in both the POA and ovary. NA upregulated the POA mRNA expression in a biphasic manner, the lower concentrations (1 ng and 10 ng) scaled up and the higher concentration (100 ng) scaled down the expression of pro-vt and pro-itb, while only the 1 ng NA scaled up the pro-ita expression. In the ovary, NA upregulated the mRNA expressions at all concentrations; the pro-vt expression was stimulated only at 10 and 100 ng. AD stimulated pro-vt and pro-ita expression in the POA at all concentrations but the pro-itb expression was inhibited at 1 and 10 ng, and stimulated at 100 ng concentrations. In the ovary, AD elicited varied effects; no significant change in pro-vt, a stimulation of pro-ita, and an inhibition of pro-itb at 1 ng, and stimulation of pro-itb at the 10 and 100 ng. The incubation of the POA and ovary with α-methylparatyrosine (MPT, 250 µg/mL, a tyrosine hydroxylase inhibitor) for 8 h downregulated the mRNA expression in the POA but unaltered the expression in the ovary. Pre-incubation with MPT for 4 h, followed by co-incubation with DA, NA or AD for 4 h elicited varied effects. In the POA, the co-incubations with the CAs rescued the inhibition due to MPT. The MPT + DA and MPT + AD treatments reduced the magnitude of the inhibition of pro-vt and pro-itb by MPT. But the pro-ita expression was modestly stimulated in the MPT + AD group. On the other hand, the MPT + NA treatment rescued the MPT effect and elicited 10-folds increase in the expression levels. In the ovary, the changes were: an inhibition in the MPT + DA group, no significant alteration in the MPT + NA group, and a mild stimulation in the MPT + AD group. The results suggest that CAs modulate brain and ovarian nonapeptide gene expression differentially, which is important in the neuroendocrine/endocrine integration of reproduction in the catfish.

Investigation on the positive chronotropic action of 6-nitrodopamine in the rat isolated atria.

6-Nitrodopamine (6-ND) is released from rat isolated atria being 100 times more potent than noradrenaline and adrenaline, and 10,000 times more potent than dopamine as a positive chronotropic agent. The present study aimed to investigate the interactions of 6-ND with the classical catecholamines, phosphodiesterase (PDE)-3 and PDE4, and the protein kinase A in rat isolated atria. Atrial incubation with 1 pM of dopamine, noradrenaline, or adrenaline had no effect on atrial frequency. Similar results were observed when the atria were incubated with 0.01 pM of 6-ND. However, co-incubation of 6-ND (0.01 pM) with dopamine, noradrenaline, or adrenaline (1 pM each) resulted in significant increases in atrial rate, which persisted over 30 min after washout of the agonists. The increased atrial frequency induced by co-incubation of 6-ND with the catecholamines was significantly reduced by the voltage-gated sodium channel blocker tetrodotoxin (1 µM, 30 min), indicating that the positive chronotropic effect of 6-ND is due in part to activation of nerve terminals. Pre-treatment of the animals with reserpine had no effect on the positive chronotropic effect induced by dopamine, noradrenaline, or adrenaline; however, reserpine markedly reduced the 6-ND (1 pM)-induced positive chronotropic effect. Incubation of the rat isolated atria with the protein kinase A inhibitor H-89 (1 µM, 30 min) abolished the increased atrial frequency induced by dopamine, noradrenaline, and adrenaline, but only attenuated the increases induced by 6-ND. 6-ND induces catecholamine release from adrenergic terminals and increases atrial frequency independently of PKA activation.

Methanolic Extract of Aerva javanica Leaves Prevents LPS-Induced Depressive Like Behavior in Experimental Mice.

Aim: Depression is a chronic recurrent neuropsychiatric disorder associated with inflammation. This study explored the pharmacological activities of Aerva javanica leaves crude extract (Aj.Cr) on lipopolysaccharide (LPS)-induced depressive-like behavior in experimental mice. Methods: Aj.Cr was evaluated for its phenolic and flavonoid contents, bioactive potential, amino acid profiling and enzyme inhibition assays using different analytical techniques followed by in-silico molecular docking was performed. In addition, three ligands identified in HPLC analysis and standard galantamine were docked to acetyl cholinesterase (AchE) enzyme to assess the ligand interaction along with their binding affinities. In in-vivo analysis, mice were given normal saline (10 mL/kg), imipramine (10 mg/kg) and Aj.Cr (100, 300, and 500 mg/kg) orally for 14-consecutive days. On the 14th day, respective treatment was given 30-minutes before intra-peritoneal administration of (0.83 mg/kg) LPS. Open field, forced swim and tail suspension tests were performed 24-hours after LPS injection, followed by a sucrose preference test 48-hours later. Serum corticosterone levels, as well as levels of nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-alpha (TNF-), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), brain-derived neurotrophic factor (BDNF) and catecholamines were determined in brain tissues. Results: In-vitro results revealed that crude extract of Aj.Cr possesses anti-depressant agents with solid antioxidant potential. In-vivo analysis showed that LPS significantly increased depressive-like behavior followed by alteration in serum and tissue biomarkers as compared to normal control (p < 0.001). While imipramine and Aj.Cr (100, 300, and 500 mg/kg) treated groups significantly (p<0.05) improved the depressive-like behavior and biomarkers when compared to the LPS group. Conclusion: The mitigation of LPS-induced depressive-like behavior by Aj.Cr may be linked to the modulation of oxidative stress, neuro-inflammation and catecholamines due to the presence of potent bioactive compounds exerting anti-depressant effects.

Physical Exercise Exerts Neuroprotective Effect on Memory Impairment by Mitigate the Decline of Striatum Catecholamine and Spine Density in a Vascular Dementia Rat Model.

OBJECTIVE: The present study aims to investigate the underlying neurochemical mechanism of physical exercise on striatum synapsis and memory function in vascular dementia model. METHODS: 32 Sprague-Dawley (SD) rats were randomly divided into 4 groups: control group (C group, n = 6), vascular dementia group (Vascular dementia group, n = 7), physical exercise and vascular dementia group (Exe-VD group, n = 6), physical exercise and black group (Exe group, n = 6). 4 weeks of voluntary wheel running were used as pre-exercise training. Vascular dementia model was established by bilateral common carotid arteries occlusion (BCCAo) for 1 week. Passive avoidance test (PAT) were used to test memory function. The level of striatum catecholamine in the microdialysate were detected by enzyme linked immunosorbent assy (ELISA). Golgi staining was used to analyze striatum neuronal spine density. RESULTS: Behavioral data indicated that 4 weeks of physical exercise ameliorated memory impairment in vascular dementia model. Striatum catecholamine level significantly decreased in VD group when compared with C group (P < .001). But this phenomenon can be rescue by physical exercise (P < .001). In addition, compared with C group, neuronal spine density significantly decreased in VD group (P < .01), but 4 weeks of physical exercise can rescue this phenomenon (P < .05). CONCLUSION: 4 weeks of physical exercise improves memory function by mitigate the decline of striatum catecholamine and spine density in VD model.

mPFC catecholamines modulate attentional capture by appetitive distracters and attention to time in a peak-interval procedure in rats.

The behavioral and neural mechanisms by which distracters delay interval timing behavior are currently unclear. Distracters delay timing in a considerable dynamic range: Some distracters have no effect on timing ("run"), whereas others seem to "stop" timing; some distracters restart ("reset") the entire timing mechanisms at their offset, whereas others seem to capture attentional resources long after their termination ("over-reset"). While the run-reset range of delays is accounted for by the Time-Sharing Hypothesis (Buhusi, 2003, 2012), the behavioral and neural mechanisms of "over-resetting" are currently uncertain. We investigated the role of novelty (novel/familiar) and significance (consequential/inconsequential) in the time-delaying effect of distracters and the role of medial prefrontal cortex (mPFC) catecholamines by local infusion of norepinephrine-dopamine reuptake inhibitor (NDRI) nomifensine in a peak-interval (PI) procedure in rats. Results indicate differences in time delay between groups, suggesting a role for both novelty and significance: inconsequential, familiar distracters "stopped" timing, novel distracters "reset" timing, whereas appetitively conditioned distracters "over-reset" timing. mPFC infusion of nomifensine modulated attentional capture by appetitive distracters in a "U"-shaped fashion, reduced the delay after novel distracters, but had no effects after inconsequential, familiar distracters. These results were not due to nomifensine affecting either timing accuracy, precision, or peak response rate. Results may help elucidate the behavioral and physiological mechanisms underlying interval timing and attention to time and may contribute to developing new treatment strategies for disorders of attention. (PsycInfo Database Record (c) 2022 APA, all rights reserved).