A new major projection from locus coeruleus: the main source of noradrenergic nerve terminals in the ventral and dorsal columns of the spinal cord

Almost all catecholamine (CA)-containing nerve terminals in the ventral column, intermediate grey and ventral half of the dorsal column disappeared after bilateral stereotaxic lesions of nucleus locus coeruleus, as revealed by fluorescence histochemistry. Some of the CA nerve terminals in the dorsal half of the column seemed to be unaffected by the lesions, as well as the CA terminals innervating the thoracic sympathetic lateral column and the band of nerve terminals crossing the midline and innervating the central grey. This coeruleo-spinal pathway in the rat is located in the anterior funiculus and the ventral parts of the lateral funiculus. A schematic map of the different CA projections to the spinal cord is presented. It was concluded that locus coeruleus innervates almost all parts of the central nervous system.

A simple method for the isolation of adrenal chromaffin granules on a large scale

Highly purified chromaffin granules can be obtained from homogenates of either ox, pig, horse or rat adrenal medullae by ultracentrifugation of the large-granule fraction layered on 1.6m-sucrose solution, by using angle-head rotors. The chromaffin granules are obtained as a pink sediment that is only slightly contaminated by mitochondria and lysosomes.

Elevated monoamine oxidase a levels in the brain: an explanation for the monoamine imbalance of major depression

CONTEXT

The monoamine theory of depression proposes that monoamine levels are lowered, but there is no explanation for how monoamine loss occurs. Monoamine oxidase A (MAO-A) is an enzyme that metabolizes monoamines, such as serotonin, norepinephrine, and dopamine.

OBJECTIVE

To determine whether MAO-A levels in the brain are elevated during untreated depression.

SETTING

Tertiary care psychiatric hospital.

PATIENTS

Seventeen healthy and 17 depressed individuals with major depressive disorder that met entry criteria were recruited from the care of general practitioners and psychiatrists. All study participants were otherwise healthy and nonsmoking. Depressed individuals had been medication free for at least 5 months.

MAIN OUTCOME MEASURE

Harmine labeled with carbon 11, a radioligand selective for MAO-A and positron emission tomography, was used to measure MAO-A DVS (specific distribution volume), an index of MAO-A density, in different brain regions (prefrontal cortex, anterior cingulate cortex, posterior cingulate cortex, caudate, putamen, thalamus, anterior temporal cortex, midbrain, hippocampus, and parahippocampus).

RESULTS

The MAO-A DVS was highly significantly elevated in every brain region assessed (t test; P=.001 to 3x10(-7)). The MAO-A DVS was elevated on average by 34% (2 SDs) throughout the brain during major depression.

CONCLUSIONS

The sizable magnitude of this finding and the absence of other compelling explanations for monoamine loss during major depressive episodes led to the conclusion that elevated MAO-A density is the primary monoamine-lowering process during major depression.

Depression, the autonomic nervous system, and coronary heart disease

Depression is a risk factor for medical morbidity and mortality in patients with coronary heart disease (CHD). Dysregulation of the autonomic nervous system (ANS) may explain why depressed patients are at increased risk. Studies of medically well, depressed psychiatric patients have found elevated levels of plasma catecholamines and other markers of altered ANS function compared with controls. Studies of depressed patients with CHD have also uncovered evidence of ANS dysfunction, including elevated heart rate, low heart rate variability, exaggerated heart rate responses to physical stressors, high variability in ventricular repolarization, and low baroreceptor sensitivity. All of these indicators of ANS dysfunction have been associated with increased risks of mortality and cardiac morbidity in patients with CHD. Further research is needed to determine whether ANS dysfunction mediates the effects of depression on the course and outcome of CHD, and to develop clinical interventions that improve cardiovascular autonomic regulation while relieving depression in patients with CHD.

Alterations in catecholamine neurons of the locus coeruleus in senile dementia of the Alzheimer type and in Parkinson's disease with and without dementia and depression

The present study provides qualitative and quantitative investigations of the norepinephrine (NE) neurons in the locus coeruleus (LC) in two neurodegenerative disorders, the senile dementia of the Alzheimer type (SDAT) and Parkinson's disease (PD). The group of PD subjects was subdivided into cases without dementia (P - D), cases with dementia, L-dopa responsive (P + D), and cases with fulminant dementia whose motor disorder symptoms were L-dopa nonresponsive (P + D/L-dopa non-responsive). NE neurons were demonstrated by immunocytochemistry against tyrosine hydroxylase (TH). Quantitations of neuronal parameters and cell numbers and three-dimensional reconstructions of the LC were carried out with a computer-assisted system. In SDAT cases, the rostrocaudal LC length (13 +/- 2.2 mm) is shorter than in controls (14.9 +/- 1.4 mm). The four basic LC neuron classes found in the normal human brain (large multipolar, large "bipolar," small multipolar, and small "bipolar" neurons; Chan-Palay and Asan: J. Comp. Neurol. this issue) are recognizable, but many cell somata are swollen and misshapen with fore-shortened, thick, and less branched dendrites. LC neuron numbers are reduced (between -3.5% and -87.5%). Neuron loss is greatest in the rostral part, less in the middle, and least in the caudal part. In PD cases, the rostrocaudal length (12.4 +/- 1.5 mm) is shorter than in SDAT and controls. The neuronal morphology is more severely altered than in SDAT. The basic neuron classes are hardly distinguishable. Most cell bodies are swollen; they frequently contain Lewy bodies; and the dendrites are short and thin with absent or reduced arborizations. Neuron numbers are more reduced than in SDAT (between -26.4% and -94.4%). Alterations are as severe caudally as rostrally in P - D, and P + D/L-dopa nonresponsive cases. P + D cases are more severely affected rostrally. The presence of depression in SDAT and Parkinson's patients is accompanied by the greatest loss of LC neurons. On the basis of morphological alterations of the TH-immunoreactive neurons, and the degree and topographical distribution of neuron loss, a differentiation is possible between the LC in normal brain and that in SDAT and PD for diagnostic purposes.

Dopaminergic neurons in the nematode Caenorhabditis elegans

Dopamine is the putative transmitter of eight neurons in the hermaphrodite form of the nematode Caenorhabditis elegans. These include the cephalic and deirid neurons, which are believed to be mechanosensory. The male has an additional six dopaminergic neurons in the tail. Mutants have been selected which have defects in the formaldehyde induced fluorescence and lack dopamine to varying degrees, but they are not insensitive to touch. The dopaminergic neurons of C. elegans are compared with the homologous neurons in Ascaris lumbricoides.

Stress hormones in mammals and birds: comparative aspects regarding metabolism, excretion, and noninvasive measurement in fecal samples

A multitude of endocrine mechanisms are involved in coping with challenges. Front-line hormones to overcome stressful situations are glucocorticoids (GCs) and catecholamines (CAs). These hormones are usually determined in plasma samples as parameters of adrenal activity and thus of disturbance. GCs (and CAs) are extensively metabolized and excreted afterwards. Therefore, the concentration of GCs (or their metabolites) can be measured in various body fluids or excreta. Above all, fecal samples offer the advantages of easy collection and a feedback-free sampling procedure. However, large differences exist among species regarding the route and time course of excretion, as well as the types of metabolites formed. Based on information gained from radiometabolism studies (reviewed in this paper), we recently developed and successfully validated different enzyme immunoassays that enable the noninvasive measurement of groups of cortisol or corticosterone metabolites in animal feces. The determination of these metabolites in fecal samples can be used as a powerful tool to monitor GC production in various species of domestic, wildlife, and laboratory animals.

Socioeconomic status is associated with stress hormones

OBJECTIVE

We assess whether socioeconomic status (SES) is associated with basal levels of cortisol and catecholamines and determine if any association between SES and these hormones can be explained (is mediated) by behavioral, social, and emotional differences across the SES gradient.

METHODS

One hundred ninety-three adult subjects, including men and women and whites and African-Americans, provided 24-hour urine catecholamine samples on each of 2 days and seven saliva cortisol samples on each of 3 days beginning 1 hour after wake-up and ending 14 to 16 hours later. Values for both hormones were averaged across days to obtain basal levels.

RESULTS

Lower SES (income and education) was associated with higher levels of cortisol and epinephrine and marginally higher levels of norepinephrine. These associations were independent of race, age, gender, and body mass. Low SES was also associated with a greater likelihood of smoking, of not eating breakfast, and with less diverse social networks. Further analyses provided evidence consistent with the hypothesis that these behavioral and social variables mediate the link between SES and the three stress hormones.

CONCLUSIONS

Lower SES was associated in a graded fashion with higher basal levels of cortisol and catecholamines. These associations occurred independent of race, and the data were consistent with mediation by health practices and social factors.

Catecholamines mediate stress-induced increases in peripheral and central inflammatory cytokines

Proinflammatory cytokines act at receptors in the CNS to alter physiological and behavioral responses. Exposure to stressors increases both peripheral and central proinflammatory cytokines, yet the mechanism(s) of induction remain unknown. Experiments here examined the role of catecholamines in the in vivo induction of proinflammatory cytokines following tailshock stress. Rats were pretreated i.p. with 2.0 mg/kg prazosin (alpha1-adrenoceptor antagonist), 10.0 mg/kg propranolol (beta-adrenoceptor antagonist), or 5.0 mg/kg labetalol (alpha1- and beta-adrenoceptor antagonist) 30 min prior to tailshock exposure and plasma interleukin-1beta (IL-1beta) and IL-6, along with tissue interleukin-1beta from the hypothalamus, hippocampus, and pituitary were measured immediately following stressor termination. Prazosin attenuated stress-induced plasma IL-1beta and IL-6, but had no effect on tissue IL-1beta levels, while propranolol attenuated plasma IL-6 and blocked tissue IL-1beta elevation, and labetalol, which cannot cross the blood-brain barrier, attenuated plasma IL-1beta and IL-6, blocked pituitary IL-1beta, but had no effect on central tissue IL-1beta levels. Furthermore, administration of 50.0 mg/kg N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride, a neurotoxin that lesions neural projections from the locus coeruleus, prevented stress-induced elevation in hippocampal IL-1beta, a region highly innervated by the locus coeruleus, but had no effect on hypothalamic IL-1beta, a region that receives few locus coeruleus projections. Finally, i.p. injection of 5.0 mg/kg isoproterenol (beta-adrenoceptor agonist) was sufficient to induce circulating IL-1 and IL-6, and tissue IL-1beta. These data suggest catecholamines play an important role in the induction of stress-induced proinflammatory cytokines and that beta-adrenoceptors are critical for tissue IL-1beta induction, while both alpha- and beta-adrenoceptors contribute to the induction of plasma cytokines.

Microelectrodes for the measurement of catecholamines in biological systems

Many of the molecules involved in biological signaling processes are easily oxidized and have been monitored by electrochemical methods. Temporal response, spatial considerations, and sensitivity of the electrodes must be optimized for the specific biological application. To monitor exocytosis from single cells in culture, constant potential amperometry offers the best temporal resolution, and a low-noise picoammeter improves the detection limits. Smaller electrodes, with 1-micron diameters, provided spatial resolution sufficient to identify the locations of release sites on the surface of single cells. For the study of neurotransmitter release in vivo, larger cylindrical microelectrodes are advantageous because the secreted molecules come from multiple terminals near the electrode, and the greater amounts lead to a larger signal that emerges from the Johnson noise of the current amplifier. With this approach, dopamine release elicited by two electrical stimulus pulses at 10 Hz was detected with fastscan cyclic voltammetry in vivo. Nafion-coated elliptical electrodes have previously been shown to be incapable of detecting such concentration changes without extensive signal averaging. In addition, we demonstrate that high-pass filtering (200 Hz) of cyclic voltammograms recorded at 300 V/s decreases the background current and digitization noise at these microelectrodes, leading to an improved signal. Also, high-pass filtering discriminated against ascorbic acid, DOPAC, and acidic pH changes, three common interferences in vivo.

Evidence of an incerto-hypothalamic dopamine neurone system in the rat

With the recently introduced glyoxylic acid histochemical fluorescence method, a previously unknown catecholamine-containing fibre system has been revealed in the zona incerta, hypothalamus and the caudal septum. These fibres, designated the incerto-hypothalamic system, have a characteristic, very delicate, finely varicose appearance, and they have a weak fluorescence, indicating an unusually low intra-neuronal amine content. On the basis of their distribution a caudal and a rostral part can be discriminated: the caudal part extends from the area of the dopamine-containing cell bodies in the caudal thalamus, the posterior hypothalamic area and the medial zona incerta (the A11 and A13 cell groups) into the dorsal part of the dorso-medial nucleus and the dorsal and anterior hypothalamic areas; the rostral part extends from the area of the rostral periventricular dopaminergic cell system (the A14 cell group) into the medial preoptic area and the periventricular and suprachiasmatic preoptic nuclei. The system probably extends also into the most caudal portion of the lateral septal nucleus. From a series of lesions and in vitro uptake studies, evidence has been obtained that the incerto-hypothalamic fibres are the projections of short, intradiencephalic dopaminergic neurones whose cell bodies are located in the A11, A13 and A14 cell groups. The projection areas of these neurones signify an involvement of the system in the control of secretion of pituitary hormones.

Malignant pheochromocytoma: effective treatment with a combination of cyclophosphamide, vincristine, and dacarbazine

STUDY OBJECTIVE

To determine the efficacy and toxicity of combination chemotherapy in patients with advanced, malignant pheochromocytoma.

DESIGN

Nonrandomized, single-arm trial.

SETTING

Governmental medical referral center.

PATIENTS

Fourteen patients with malignant pheochromocytoma confirmed by histologic tests. All patients had metastatic disease and elevated urinary catecholamine secretion.

INTERVENTIONS

After optimization of antihypertensive therapy, patients received cyclophosphamide, 750 mg/m2 body surface area on day 1; vincristine, 1.4 mg/m2 on day 1, and dacarbazine, 600 mg/m2 on days 1 and 2, every 21 days.

MEASUREMENTS AND MAIN RESULTS

Combination chemotherapy with cyclophosphamide, vincristine, and dacarbazine produced a complete and partial response rate of 57% (median duration, 21 months; range, 7 to more than 34). Complete and partial biochemical responses were seen in 79% of patients (median duration, more than 22 months; range, 6 to more than 35). All responding patients had objective improvement in performance status and blood pressure. Toxicity included expected hematologic, neurologic, and gastrointestinal effects of chemotherapy without serious sequelae. There were four minor hypotensive episodes and one minor hypertensive episode.

CONCLUSIONS

Combination chemotherapy with cyclophosphamide, vincristine, and dacarbazine is effective for advanced malignant pheochromocytoma. Urinary catecholamines are useful to ascertain biochemical response to therapy.

Overeating and obesity from damage to a noradrenergic system in the brain

A discrete, ascending fiber system that supplies the hypothalamus with most of its noradrenergic terminals was destroyed at midbrain level, both electrolytically and with local injections of 6-hydroxydopamine, a destructive agent specific for catecholaminergic neurons. The result was hyperphagia leading to obesity. Fluorescence histochemical analysis showed that loss of noradrenergic terminals in ventral bundle termination areas such as the hypothalamus was necessary for hyperphagia. Damage to dorsal bundle or dopaminergic projections was not. Prior treatment with desmethylimipramine to selectively block uptake of 6-hydroxydopamine into noradrenergic neurons prevented both hyperphagia and loss of norepinephrine fluorescence. The lesions that produced hyperphagia also reduced the potency of d-amphetamine as an appetite suppressant. It is concluded that this noradrenergic bundle normally mediates suppression of feeding, thereby influences body weight, and serves as a substrate for d-amphetamine-induced loss of appetite.

Beta-adrenergic neuroeffector abnormalities in the failing human heart are produced by local rather than systemic mechanisms

In order to investigate the general cause of beta-adrenergic receptor neuroeffector abnormalities in the failing human heart, we measured ventricular myocardial adrenergic receptors, adrenergic neurotransmitters, and beta-adrenergic receptor-effector responses in nonfailing and failing hearts taken from nonfailing organ donors, subjects with endstage biventricular failure due to idiopathic dilated cardiomyopathy (IDC), and subjects with primary pulmonary hypertension (PPH) who exhibited isolated right ventricular failure. Relative to nonfailing PPH left ventricles, failing PPH right ventricles exhibited (a) markedly decreased beta 1-adrenergic receptor density, (b) marked depletion of tissue norepinephrine and neuropeptide Y, (c) decreased adenylate cyclase stimulation in response to the beta agonists isoproterenol and zinterol, and (d) decreased adenylate cyclase stimulation in response to Gpp(NH)p and forskolin. These abnormalities were directionally similar to, but generally more pronounced than, corresponding findings in failing IDC right ventricles, whereas values for these parameters in nonfailing left ventricles of PPH subjects were similar to values in the nonfailing left ventricles of organ donors. Additionally, relative to paired nonfailing PPH left ventricles and nonfailing right ventricles from organ donors, failing right ventricles from PPH subjects exhibited decreased adenylate cyclase stimulation by MnCl2. These data indicate that: (a) Adrenergic neuroeffector abnormalities present in the failing human heart are due to local mechanisms; systemic processes do not produce beta-adrenergic neuroeffector abnormalities. (b) Pressure-overloaded failing right ventricles of PPH subjects exhibit decreased activity of the catalytic subunit of adenylate cyclase, an abnormality not previously described in the failing human heart.

Distribution of acetylcholine and catecholamine neurons in the cat brainstem: a choline acetyltransferase and tyrosine hydroxylase immunohistochemical study

The distribution of acetylcholine neurons in the brainstem of the cat was studied by choline acetyltransferase (ChAT) immunohistochemistry and compared to that of catecholamine neurons examined in the same or adjacent sections by tyrosine hydroxylase (TH) immunohistochemistry. The largest group of ChAT-positive (+) neurons was located in the lateral pontomesencephalic tegmentum within the pedunculopontine tegmental nucleus and the laterodorsal tegmental nucleus rostrally and within the parabrachial nuclei and locus coeruleus nucleus more caudally. TH+ neurons were found to be coextensive and intermingled with ChAT+ neurons in the dorsolateral pontomesencephalic tegmentum, where the number of ChAT+ cells (approximately 18,500) exceeded that of the TH+ cells (approximately 12,000). In the caudal pons, scattered ChAT+ neurons were situated in the ventrolateral tegmentum together with TH+ neurons. In the medulla, numerous ChAT+ cells were located in the lateral tegmental field, where they extended in a radial column from the dorsal motor nucleus of the vagus to the ventrolateral tegmentum around the facial and ambiguus nuclei, occupying the position of preganglionic parasympathetic neurons of the 7th, 9th, and 10th cranial nerves. TH+ cells were also present in this field. Neurons within the general visceral, special visceral, and somatic motor cranial nerve nuclei were all immunoreactive to ChAT. Scattered ChAT+ neurons were also present within the medullary gigantocellular and magnocellular tegmental fields together with a small number of TH+ neurons. Other groups of ChAT+ cells were identified within the periolivary nuclei, parabigeminal nucleus, prepositus hypoglossi nucleus, and the medial and inferior vestibular nuclei. Acetylcholine neurons thus constitute a heterogeneous population of cells in the brainstem, which in addition to including the somatic and visceral efferent systems, comprises many other discrete systems and represents an important component of the brainstem reticular formation. The proximity to and interdigitation with catecholamine neurons within these systems may be of important functional significance.