Functionalized Acupuncture Needle as Surface-Enhanced Resonance Raman Spectroscopy Sensor for Rapid and Sensitive Detection of Dopamine in Serum and Cerebrospinal Fluid.

It is a challenge to develop a robust sensor for simple, rapid operation and sensitive detection of neurotransmitters in complex specimens. Herein, ferric citrate functionalized gold nanoparticles (CA-FeIII /Au NPs) are utilized to develop a facile sensor based on surface-enhanced resonance Raman spectroscopy (SERRS) for sensitive detection of dopamine (DA). The sensor is prepared by decorating the acupuncture needle with Au NPs, which enables sufficient surface-enhanced Raman spectroscopy enhancement. The CA-FeIII structure is highly sensitive and selective for DA due to the formation of the CA-FeIII -DA resonant structure; this indicates the advantages of capturing, carrying, and separating DA molecules from complicated samples in a simple operation. Furthermore, the practical application of the fabricated sensor is validated by the detection of DA in pretreated serum and cerebrospinal fluid of acupuncture-treated mice with detection limits of 0.1 and 2.5 nm DA, respectively. The developed active acupuncture needle sensor has potential benefits for sensitive detection and qualitative identification of DA molecules from biological samples.

Design, biometric simulation and optimization of a nano-enabled scaffold device for enhanced delivery of dopamine to the brain.

This study focused on the design, biometric simulation and optimization of an intracranial nano-enabled scaffold device (NESD) for the site-specific delivery of dopamine (DA) as a strategy to minimize the peripheral side-effects of conventional forms of Parkinson's disease therapy. The NESD was modulated through biometric simulation and computational prototyping to produce a binary crosslinked alginate scaffold embedding stable DA-loaded cellulose acetate phthalate (CAP) nanoparticles optimized in accordance with Box-Behnken statistical designs. The physicomechanical properties of the NESD were characterized and in vitro and in vivo release studies performed. Prototyping predicted a 3D NESD model with enhanced internal micro-architecture. SEM and TEM revealed spherical, uniform and non-aggregated DA-loaded nanoparticles with the presence of CAP (FTIR bands at 1070, 1242 and 2926 cm(-1)). An optimum nanoparticle size of 197 nm (PdI=0.03), a zeta potential of -34.00 mV and a DEE of 63% was obtained. The secondary crosslinker BaCl(2) imparted crystallinity resulting in significant thermal shifts between native CAP (T(g)=160-170 degrees C; T(m)=192 degrees C) and CAP nanoparticles (T(g)=260 degrees C; T(m)=268 degrees C). DA release displayed an initial lag phase of 24 h and peaked after 3 days, maintaining favorable CSF (10 microg/mL) versus systemic concentrations (1-2 microg/mL) over 30 days and above the inherent baseline concentration of DA (1 microg/mL) following implantation in the parenchyma of the frontal lobe of the Sprague-Dawley rat model. The strategy of coupling polymeric scaffold science and nanotechnology enhanced the site-specific delivery of DA from the NESD.

A history of iron deficiency anemia during infancy alters brain monoamine activity later in juvenile monkeys.

Both during and after a period of iron deficiency (ID), iron-dependent neural processes are affected, which raises the potential concern that the anemia commonly experienced by many growing infants could have a protracted effect on the developing brain. To further investigate the effects of ID on the immature brain, 49 infant rhesus monkeys were evaluated across the first year of life. The mothers, and subsequently the infants after weaning, were maintained on a standardized diet containing 180 mg/kg of iron and were not provided other iron-rich foods as treats or supplements. As the infants grew, they were all screened with hematological tests, which documented that 16 (33.3%) became markedly ID between 4 and 8 months of age. During this anemic period and subsequently at 1 year of age, cerebrospinal fluid (CSF) specimens were collected to compare monoamine activity in the ID and iron-sufficient infants. Monoamine neurotransmitters and metabolite levels were normal at 4 and 8 months of age, but by 1 year the formerly anemic monkeys had significantly lower dopamine and significantly higher norepinephrine levels. These findings indicate that ID can affect the developmental trajectory of these two important neurotransmitter systems, which are associated with emotionality and behavioral performance, and further that the impact in the young monkey was most evident during the period of recovery.

Norman Cousins Lecture. Mechanisms of cytokine-induced behavioral changes: psychoneuroimmunology at the translational interface.

Work in our laboratory has focused on the mechanisms by which cytokines can influence the brain and behavior in humans and non-human primates. Using administration of interferon (IFN)-alpha as a tool to unravel these mechanisms, we have expanded upon findings from the basic science literature implicating cytokine-induced changes in monoamine metabolism as a primary pathway to depression. More specifically, a role for serotonin metabolism has been supported by the clinical efficacy of serotonin reuptake inhibitors in blocking the development of IFN-alpha-induced depression, and the capacity of IFN-alpha to activate metabolic enzymes (indolamine 2,3 dioxygenase) and cytokine signaling pathways (p38 mitogen activated protein kinase) that can influence the synthesis and reuptake of serotonin. Our data also support a role for dopamine depletion as reflected by IFN-alpha-induced changes in behavior (psychomotor slowing and fatigue) and regional brain activity, which implicate the involvement of the basal ganglia, as well as the association of IFN-alpha-induced depressive-like behavior in rhesus monkeys with decreased cerebrospinal fluid concentrations of the dopamine metabolite, homovanillic acid. Neuroimaging data in IFN-alpha-treated patients also suggest that activation of neural circuits (dorsal anterior cingulate cortex) associated with anxiety and alarm may contribute to cytokine-induced behavioral changes. Taken together, these effects of cytokines on the brain and behavior appear to subserve competing evolutionary survival priorities that promote reduced activity to allow healing, and hypervigilance to protect against future attack. Depending on the relative balance between these behavioral accoutrements of an activated innate immune response, clinical presentations may be distinct and warrant individualized therapeutic approaches.

Opposite changes in dopamine metabolites and met-enkephalin levels in the ventricular CSF of patients subjected to thalamic electrical stimulation.

High-frequency electrical stimulations of thalamic nuclei are currently used for the suppression of parkinsonian or essential tremor and for the relief of some types of intractable pain in man. However, the mechanisms by which such stimulations exert their therapeutic effects are essentially unknown. Attempts were made to provide some insight into these mechanisms by measuring the levels of the dopamine metabolites homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC), the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and met-enkephalin-like immunoreactivity in ventricular cerebrospinal fluid (CSF) of patients with Parkinson's disease (PD) or multiple sclerosis (MS) after a 30-minute therapeutic electrical stimulation of the ventralis intermedius nucleus of the thalamus. In nonstimulated control patients, the levels of these compounds did not significantly differ in two CSF samples taken 30 minutes apart. In stimulated patients, a decrease in dopamine metabolite levels associated with a relative increase in met-enkephalin-like immunoreactivity were observed in the CSF sample taken after the 30-minute stimulation as compared to the sample taken immediately before the stimulation. In contrast, the levels of 5-HIAA remained unaffected by the stimulation. These data confirmed the existence of negative interactions between dopaminergic and enkephalinergic systems in man similar to those previously demonstrated in rats. In addition, they suggest that alterations in dopaminergic or enkephalinergic neurotransmission might be involved in the therapeutic action of thalamic electrical stimulation in patients with parkinsonian symptoms and other patients.

Evidence for central hypertyraminemia in hepatic encephalopathy.

In mongrel dogs, the effect of end-to-side portacaval shunt on plasma, cerebrospinal fluid (CSF) and brain tyramine, tyrosine, dopamine, norepinephrine, and epinephrine were studied. It was found that the level of tyramine in plasma, CSF, and selected brain regions increased steadily after the construction of the shunts. These elevations became more pronounced when the dogs manifested symptoms of hepatic encephalopathy. In postshunted dogs with stage II and III hepatic encephalopathy, tyramine concentration in corpus striatum (1,312 +/- 371), hypothalamus (400 +/- 67.0), and midbrain (660 +/- 78.7 ng/g) was significantly (P less than 0.05) higher than the level in dogs with stage 0 and I hepatic encephalopathy and sham-operated dogs serving as controls (corpus striatum, 831 +/- 140; hypothalamus, 167 +/- 40.0; and midbrain, 132 +/- 37.4 ng/g). This was followed by a concomitant depletion of dopamine and norepinephrine in these brain regions (postshunt: dopamine 104 +/- 20.0, 3,697 +/- 977, and 105 +/- 14.1; norepinephrine 521 +/- 71.6, 81.6 +/- 13.7, and 218 +/- 31.7 ng/g; vs. sham group: dopamine 532 +/- 83.1, 8,210 +/- 1,126, and 192 +/- 35.0; norepinephrine 1,338 +/- 425, 124 +/- 21.3, and 449 +/- 89.7 ng/g) of encephalopathic dogs with portacaval shunt. Furthermore, tyramine, tyrosine, dopamine, and norepinephrine levels in plasma and CSF increased markedly as clinical features in the dogs' behavior characteristic of hepatic encephalopathy occurred, including hypersalivation, ataxia, flapping tremor, somnolence, and coma. Cerebral hypertyraminemia and a defect in sympathetic neurotransmission may contribute to the development of hepatic encephalopathy of liver disease.

Dorsal column stimulation: Effect on human cerebrospinal fluid and plasma catecholamines.

Plasma and cerebrospinal fluid catecholamines were measured in three patients with multiple sclerosis who had dorsal column stimulators placed at the T5-7 levels. Stimulation for 3 minutes and 20 minutes increased release of plasma norepinephrine, epinephrine, and dopamine, as well as norepinephrine into the cerebrospinal fluid. Neither dopamine nor epinephrine was released into the spinal fluid during or after stimulation. Percutaneous stimulation did not release catecholamines into the plasma or spnal fluid, suggesting that these findings were not simply related to sensory stimulation or stress. Plasma catecholamine levels were inconsistently correlated with pulse rate changes during and after stimulation but not with blood pressure, although the changes in pulse rate and blood pressure were relatively small compared to changes in plasma catecholamines. This study suggests that plasma catecholamines and spinal fluid norepinephrine reflect central activation of sympathetic nervous system pathways and are more reliable indicators of sympathetic activity than changes in cardiovascular function.

Transformation of 3H-dopamine during transport from CSF to hypophysial portal blood.

The capacity of the hypothalamus to transport dopamine from brain tissue into hypophysial portal blood was investigated. One hour after injection 10 muCi of 3H-dopamine into a lateral ventricle of male rats, radioactivity was present in the brain, in the anterior pituitary gland, and in systemic plasma. The highest concentration of radioactivity was found in the hypothalamus, whereas the lowest was found in systemic plasma. The cerebrum and systemic plasma contained over 50% of the dose injected, whereas the anterior pituitary gland contained no more than 0.2%. Three doses of 3H-dopamine (0.1, 1, 1nd 10 muCi) were injected into a lateral ventricle, and hypophysial portal and arterial blood were collected at 7 mu1/min for two hours. Ten min after injection, radioactivity was detected in hypophysial portal blood, reached a peak within 15-20 min, and then declined gradually to attain a concentration similar to that in arterial blood. Portal and arterial plasma and tissue extracts from rats injected intraventricularly with 3H-dopamine were subjected to gel filtration on a Sephadex G-10 comumn and to paper electrophoresis. The hypothalamus as well as the cerebrum contained several radiolabeled substances one of which appeared to behave like 3H-dopamine. However, no free 3H-dopamine was evident at this time either in blood or in the anterior pituitary gland. The results of chromatography and electrophoresis of dialyzed portal plasma indicate that much of the radioactivity was bound to macromolecules (probably plasma proteins) larger than 10,000-12,000 molecular weight. When the radioactive compound was dissociated from the macromolecule with perchloric acid, the dissociated compound did not behave as free 3H-dopamine as judged by gel filtration and electrophoresis. It is concluded that a transformation of 3H-dopamine occurred during passage from the CSF to blood and that no 3H-dopamine was present in portal blood. A large portion of the radioactivity was bound to plasma macromolecules.