Philip A. Shea

Sympathetic innervation of murine thymus and spleen: evidence for a functional link between the nervous and immune systems.

Sympathetic innervation was demonstrated in both perivascular and parenchymal regions of murine thymus and spleen. Catecholamine varicosities were associated with mast cells in these areas. The antibody response to sheep red blood cells of 7 week old mice that had been sympathectomized with six-hydroxydopamine (6OHDA) at birth was significantly elevated compared with saline treated controls. Alpha-methyl tyrosine (alpha-MT) and 6OHDA treatment of mice, producing a more complete sympathectomy, showed a significantly enhanced anti-SRBC response with respect to mice treated with alpha-MT or 6OHDA alone. Catecholamine levels in thymus, spleen, and adrenals of both experimental and control mice were measured using liquid chromatography with electrochemical detection (LCEC). The present study suggests that the sympathetic nervous system has a functional role in modulating the humoral immune response in vivo.

Effects of streptozotocin diabetes on the noradrenergic innervation of the rat heart: A longitudinal histofluorescence and neurochemical study

The effects of the age of induction and total duration of streptozotocin diabetes on the sympathetic noradrenergic innervation of the rat heart was examined with glyoxylic acid induced histofluorescence to demonstrate the distribution of noradrenergic fibers within the heart, and with high performance liquid chromatography with electrochemical detection to measure tissue levels of the neurotransmitter norepinephrine. Diabetes was induced in male Sprague-Dawley rats at 1, 2, and 4 months of age. Within each of these groups, diabetic rats survived for periods of 1, 2, and 4 months. Additional groups of diabetic rats survived to a chronological age of 8 months. Norepinephrine levels in the hearts of diabetic rats were increased over those of control rats in all groups at 1 month duration of diabetes. Ventricles were generally affected to a greater extent than atria. At 2 months duration of diabetes, ventricular levels remained elevated while atrial norepinephrine levels were at or below control levels. At 4 months duration of diabetes, and in all groups at 8 months of age, the norepinephrine levels were at or below control levels, except in the ventricles of rats induced at 4 months of age, which remained elevated. Histofluorescence studies demonstrated the presence of axon bundles and varicose noradrenergic profiles in the diabetic rat hearts, distributed in a pattern similar to that seen in controls. However, at 1 month duration of diabetes in all groups, the density of noradrenergic varicosities in diabetic rat hearts appeared increased with abundant branched profiles. These results are surprising, since studies on genetic models of diabetes have suggested decreased norepinephrine levels in the heart. The present study suggests that during the early phases of streptozotocin induced diabetes, noradrenergic nerves are still intact and may be susceptible to pharmacologic manipulation. The later fall of norepinephrine levels back to or below control levels may indicate actual neuronal damage, suggesting that early intervention may be necessary to protect these nerves from degeneration. This issue is potentially important in view of the reported toxic effects of high NE levels on the heart, and the high incidence of death from myocardial infarct in diabetic humans with autonomic neuropathy.

In vivo determination of endogenous biogenic amines in rat brain using HPLC and push-pull cannula.

Abstract Combining the methods of push-pull cannulation with those of high performance liquid chromatography (HPLC), we have measured the content of a number of biogenic amines in the perfusate of freely moving rats. In an initial study, the lateral hypothalamus (LH) was chronically implanted with a push-pull cannula and was perfused with 0.9% NaCl. Fifteen minute samples were collected through the push-pull cannula (flow rate: 25 μl/min) and aliquots of 200 μl were injected into the HPLC without any extraction or prepurification procedure. Simultaneous determination of the levels of 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), norepinephrine (NE) and dopamine (DA) in the perfusate was accomplished by means of HPLC with electrochemical detection. The HPLC system utilized a C-18 reverse phase column coupled with a glassy carbon detector. Results indicate that this combination of push-pull perfusions and HPLC assay can provide a simple, rapid, and sensitive technique for the in vivo simultaneous determination of the compounds released in discrete brain areas. In preliminary studies in which these methods were used, 50 mg/kg D,L-5-HTP was injected subcutaneously (SC) into rats implanted with push-pull cannulae and working on a variable interval (VI 1) schedule of reinforcement. Increases in 5-HTP, 5-HT and 5-HIAA were measured during the period of behavioral depression following 5-HTP administration. This technique could provide a useful tool in the assessment of neurochemical changes in brain during ongoing steady-state behaviors or during the disruption of behavior following administration of drugs, precursors, or other perturbations.

Serotonergic changes in specific areas of rat brain associated with activity--stress gastric lesions.

&NA; To study serotonergic involvement in the development of gastric lesions following activity wheel stress, three groups of rats (gastric lesions, no gastric lesions, and home—cage controls) were killed following exposure to the experimental procedures. The brains were dissected into eight specific areas and subjected to analyses for serotonin (5‐HT) and 5‐hydroxyindoleacetic acid (5‐HIAA) using high performance liquid chromatography with EC detection. Lower levels of 5‐HT were found in the midbrain, cortex, and hippocampus of rats with gastric lesions compared to either the no lesion group, subjected to shorter periods of activity—stress, or the home—cage control group. Levels of 5‐HT and 5‐HIAA were elevated in the pons/medulla oblongata of both the lesion and the no lesion groups compared to the home—cage controls. Corticosterone levels in blood were also significantly elevated in the lesion group. These data on serotonin changes in the CNS suggest a possible role for this neurotransmitter in stress‐induced gastric pathology.

Biological stress responses in high and low trait anxious students

In an investigation of biological indicators of stress in normal humans, undergraduate psychology students were differentiated on trait anxiety and assessed under baseline, preexam (stress), and postexam conditions. Assessment at each condition involved drawing 20 ml of blood, followed by self-reporting for selected questionnaires. Self-reports included state anxiety, general psychological symptomatology, dysfunctional attitudes, academic confidence, sleep patterns, and intake of drugs, including alcohol and caffeine. Blood was analyzed for whole blood serotonin content, plasma MHPG, and platelet imipramine binding. Baseline differences between high and low trait anxious students on biological measures were significant only for whole blood serotonin content. Variation across situational conditions was significant for whole blood serotonin, with an increase under the stressful condition for both anxiety groups. Thus, serotonin is highlighted as an important factor in the human response to stress, whereas expected differences in MHPG were not observed. The serotonergic response to stress was not explained by changes in psychological or physical state variables. Changes in serotonin content were positively correlated with changes in platelet imipramine binding.

Effect of Chronic Haloperidol on the Levels of Blood and Urinary Phenylethylamine and Phenylacetic Acid in Rats

Phenylethylamine (PE) and/or its major metabolite phenylacetic acid (PAA) have been suggested to be involved in the pathophysiology of schizophrenia ard the major affective disorders. In the majority of past studies on PE and PAA levels in urine of psychiatric patients, it has not been clear whether subjects were still receiving or recently withdrawn from antipsychotic medication. It is possible that such medication may contribute to changes in PE dynamics either during treatment or following withdrawal, though this possibility has not been thoroughly tested. Therefore, in a preliminary experiment we have directly tested the effects of a chronic neuroleptic schedule on the levels of PE in both blood and urine, and the levels of PAA in urine, of rats. Urinary excretion of these compounds was studied prior to drug treatment, during chronic treatment, and following withdrawal, while blood PE levels were observed immediately after and five days after the completion of a chronic treatment schedule.

Comparison of MAO, D β H, and COMT activities in chronic schizophrenics selected on the basis of nailfold capillary pattern

A group of 17 white male chronic schizophrenic subjects were divided on the basis of plexus visualization score (PVS). High and low PVS subjects were compared to each other and to low PVS controls on measures of platelet monamine oxidase (MAO), rbc catechol‐o‐methyl transferase (COMT), and plasma dopamine‐β‐hydroxylase (DβH). There were no differences between high and low PVS subjects on any biochemical variable. Schizophrenic subjects had lower platelet MAO activity than controls. Platelet MAO and rbc COMT were significantly correlated in schizophrenic subjects.

Serotonin, Imipramine Binding, Cortisol and Anxiety in Humans Under Stress

Although noradrenergic and serotonergic neurotransmitter systems have been implicated in stress among animals and humans [1,4] specific biological indicators of human stress have produced inconsistent results [3].