Evidence of nitrate-based nighttime atmospheric nucleation driven by marine microorganisms in the South Pacific

Our understanding of ocean-cloud interactions and their effect on climate lacks insight into a key pathway: do biogenic marine emissions form new particles in the open ocean atmosphere? Using measurements collected in ship-borne air-sea interface tanks deployed in the Southwestern Pacific Ocean, we identified new particle formation (NPF) during nighttime that was related to plankton community composition. We show that nitrate ions are the only species for which abundance could support NPF rates in our semicontrolled experiments. Nitrate ions also prevailed in the natural pristine marine atmosphere and were elevated under higher sub-10 nm particle concentrations. We hypothesize that these nucleation events were fueled by complex, short-term biogeochemical cycling involving the microbial loop. These findings suggest a new perspective with a previously unidentified role of nitrate of marine biogeochemical origin in aerosol nucleation.

[Deliberate interruptions and changes of dose of inhaled corticosteroids by asthma patients: "a community pharmacy study"]

BACKGROUND

Adherence to inhaled corticosteroids (ICS) remains a major issue for asthma management, even among patients receiving a regular prescription from their doctor. The frequency of deliberate interruption of ICS, and of spontaneous changes of dose, were studied in a population of asthma patients recruited in community pharmacies.

METHODS

Asthma patients (aged 18-50) recruited in community pharmacies reported in self-administered questionnaires their spontaneous interruptions and changes of doses of ICS during the past 3 months. The characteristics of patients who interrupted their therapy or who modified the dose were compared with other patients.

RESULTS

The studied population included 252 patients (mean age 35 year-old, females: 59%), of whom 62% had inadequately controlled asthma. Among these patients, 25% had interrupted ICS therapy during the past 3 months, while 21% spontaneously changed the dose. The most reported reason for interrupting ICS was the cessation of symptoms (50%). In multivariate analysis, interrupting ICS was mainly associated with inadequate asthma control (OR=3.1, 95% CI 1.5-6.4), while the strongest association with changing ICS doses was the patients' perception of asthma as a concern in their lives (OR=3.2, 95% CI 1.2-8.4).

CONCLUSION

These results underline a poor understanding of the purpose of ICS therapy by patients. They also highlight the need of therapeutic education to improve the management of the disease.

Patient-reported adverse events under asthma therapy: a community pharmacy-based survey

The characteristics of patients who report adverse events (AEs) attributed to asthma therapy have been little investigated. Asthma patients aged 18-50 years were surveyed in pharmacies. Patients completed a questionnaire linked to computerized records of dispensed medications. Patients reported all AEs that they attributed to asthma therapy. The correlates of reporting 2+ AEs were identified. Almost 59% of the 1,351 patients (mean age: 37, 56% females) attributed AEs to asthma therapy, and 35% at least two. Most common AEs included tiredness (21.8%) and palpitations (21.1%). Poor asthma control and perception of asthma as a handicap were the major correlates of reporting 2+ AEs (odds ratio (OR)=2.5, 95% confidence interval (CI)=[1.7-3.7] and OR=1.9, 95% CI=[1.4-2.5]). Other significant correlates included age >30 years, female gender, and receiving psychotropic therapy. Inadequate control may partly account for AEs attributed by patients to asthma therapy. Improving patients' education may help to improve acceptability of asthma therapy.

Medication use and disease control of asthmatic patients in Flanders: a cross-sectional community pharmacy study

The aim of this study was to describe medication use and disease management of asthmatic patients and to evaluate the usefulness of the Asthma Control Test (ACT) in community pharmacies. In 54 Flemish community pharmacies 166 asthmatic patients were included in the study. At inclusion, the study persons completed a survey to assess subject characteristics, symptoms and asthma attacks, and peak expiratory flow (PEF) was measured. Furthermore, the actual level of asthma control was assessed by ACT, a clinically validated measure of asthma control. Prescribed medicine data of the patients were 1 year retrospectively analysed from the prescriptions. Mean age of the sample was 36.8 year, 23% were smokers. As maintenance treatment, 63% of the patients used a combination product containing an inhaled corticosteroid and a long-acting beta2-agonist in a single inhaler. According to ACT, 49.1% of the patients were insufficiently controlled. Only 4.9% of the patients had a maximal ACT score of 25, indicating complete asthma control; 46.0% of the study population obtained an ACT score between 20 and 24, meaning that their asthma is well controlled. In contrast, 30.7% of the patients had a score between 15 and 19, indicating uncontrolled asthma. In all, 18.4% obtained ACT scores of less than 15, meaning that their asthma was seriously out of control and necessitating referral to their general practitioner or lung specialist. Importantly, the correlation between the self-perceived level of asthma control and the objective assessment of the asthma control level was poor: 82.3% of the patients believed their asthma to be totally or well controlled, while this was the fact for only 50.9% of the patients. In conclusion, the ACT appears to be a useful tool to determine rapidly and accurately the level of asthma control in patients presenting at community pharmacies.

Management of asthma in patients supervised by primary care physicians or by specialists

French asthma patients may be supervised by general practitioners (GPs) and/or specialists. Therefore, this study examined asthma management in patients exclusively supervised by specialists (SPE), GPs, (GP) and both (GP+SPE group), and compared the findings. Asthma patients were consecutively recruited in 348 pharmacies. Each patient completed a questionnaire providing data on personal characteristics, asthma management, perception of disease and asthma supervision. Asthma control was measured using the Asthma Control Test. Questionnaires were linked to computerised records of medications which had been dispensed before inclusion in the study. From the 1,256 patients (mean age = 36.1 yrs, 54.3% females), 11.4, 36.6, and 52.0% were placed in the SPE, GP, and GP+SPE groups, respectively. During the previous 4 weeks, most patients in the SPE group were properly controlled (52.2 versus 26.4 and 21.5% in GP and GP+SPE groups, respectively). The SPE group made more use of fixed combinations of long-acting beta agonist and inhaled corticosteroid, while receiving less short-acting beta agonists, antitussives and antibiotics. Striking differences in symptoms and asthma management were observed according to the type of asthma supervision. The current results strongly support the need to improve the management of asthma in primary care, and the coordination of care between general practitioners and specialists.

Quality of asthma care: results from a community pharmacy based survey

BACKGROUND

Optimal control is a major objective of disease management of asthma. The aim of the present study was to provide descriptive data on disease management in asthma patients, including medical resource utilization.

METHODS

Asthma patients (age 18-50 years) were consecutively recruited in 348 dispensing pharmacies. They completed a questionnaire which collected data on personal characteristics, asthma management, including medical resource utilization, including asthma management. Asthma control was measured with the Asthma Control Test. Data from computerized pharmacy records of medications, dispensed before inclusion, were also collected.

RESULTS

In 1791 eligible patients, 1559 accepted to participate in the study (mean age = 36.5, 56.1% of females). During the previous 4 weeks, the asthma control was satisfactory for only 28% of the patients, despite extensive provision of anti-inflammatory asthma control treatments (89%). Combinations of long acting beta agonists (LABA) and inhaled corticosteroids (ICS) were commonly used (59%), while fewer patients received LABA and ICS as two separate medications (15%). In addition, short-acting beta agonists, were frequently dispensed (71%). A substantial number of patients consulted their GPs on a monthly basis. Patients commonly reported daily shortness of breath (30%), daily use of rescue medication (29%) and weekly nocturnal symptoms (32%). Surprisingly, most patients considered their asthma as completely or well controlled (76%).

CONCLUSIONS

Our results clearly identify a need to improve the management of asthma. Education programmes would be beneficial to improve asthma control.

[Is there an interaction between sleep-disordered breathing, depression and apolipoprotein E phenotype?]

Sleep-disordered breathing (SDB) is widely underdiagnosed among adults. However, SDB may be considered as a public health problem because of clinical consequences for the patient: impaired awake performance, increased risk factor for cardiovascular diseases and increased prevalence of depression. Apolipoprotein E (apoE), a protein involved in lipid metabolism, has 3 major alleles e2, e3 and e4. Recently, it has been shown that apoE e4 allele, a well-known risk factor for cardiovascular diseases, was also associated with SDB. In this study, we assessed a potential interaction between SDB, depression and apoE phenotype. 92 male patients (36-79 years old, mean age 58.0 11.2) consulting in hospital for SDB were enrolled in the study. Each patient had the following exams: 1) overnight polysomnography to determine apnea/hypopnea index (AHI=average number of respiratory events 10 seconds with no breathing per hour). A moderate-to-severe SDB was defined with AHI 15. 2) a psychiatric examination to look for previous or present symptoms of depressive illness. 3) blood sampling to determine apoE genotype (using PCR-RFLP method). In our study, allele frequencies for apoE e2, e3 and e4 were similar to those reported in general population. Among 92 patients, 68 (74%) presented moderate-to-severe SDB and 28 (30%) previous or present symptoms of depressive illness. Our results indicate that: 1) apoE e4 was significantly associated with moderate-to-severe SDB (n=92, p=0.03), 2) scores of apnea-hypopnea index were significantly higher in e4-positive versus e4-negative participants (n=57, p=0,05) and 3) ApoE and depression were not linked. This study confirms a potential interaction between SDB and apoE phenotype, as recently reported. This suggests that e4 allele might be a genetic risk factor for SDB (e4 allele frequency higher in patients with moderate-to-severe SDB versus general population) and/or consequently a deleterious factor for this pathology (increased AHI in e4-positive versus e4-negative patients). Depression might be only one of clinical consequences of SDB. Thus, SDB leads to repeated hypoxemia and numerous awakenings resulting in fatigue and decreased cognitive abilities suitable to the onset of depressive illness in vulnerable persons.

Missense mutation in exon 11 (Codon 378) of the presenilin-1 gene in a French family with early-onset Alzheimer's disease and transmission study by mismatch enhanced allele specific amplification. Mutations in brief no. 141. Online. besancon@rockefeller1.univ.lyon1.fr

Mutations in the presenilin-1 (PS1) gene account for the majority of familial early-onset Alzheimer's disease (EOAD) cases. We screened the coding part of the PS1 gene for the present of mutations in a French family with EOAD, using single strand conformation polymorphism (SSCP) analysis. Patients in the pedigree showed a missense mutation in exon 11 of the PS1 gene involving a transition of G to A, altering glycine to glutamate at codon 378. The cosegregation of the mutation with EOAD in the family was studied by allele specific amplification, enhanced by the introduction of a mismatch at the penultimate position near the 3' primer end. The mutation has not been described before and is located within the third large cytoplasmic loop and may lead to the appearance of a short additional a-helix.

Alternative exon 3 splicing of the human major protein zero gene in white blood cells and peripheral nerve tissue

The major protein zero (MPZ) is involved in peripheral myelin folding. Using nested reverse transcription-PCR, we amplified several fragments of MPZ mRNAs in white blood cells and in peripheral nerve tissue. Cloning of PCR products revealed the existence of three alternative splicing patterns: one resulted in the complete loss of exon 3 and two others induced partial skipping of the exon 3 sequence. All three alternative splicing mechanisms produced a frame-shift and created an identical premature stop codon in exon 4. We conclude that the existence of these MPZ RNA transcript variants may be the result of deliberate splicing decisions and may have functional implications in the cell.

The role of the French community pharmacist in drug dispensing

Pharmacists are in charge of decreasing the risk of drug related morbidity and then enhance the quality of drug therapy. A survey of the optimization of pharmacotherapy carried out by 37 pharmacists during six weeks. When dispensing drugs, pharmacists have detected drug related problems, such as lack of precision in prescriptions, abnormalities in dosing, interactions, contraindications, adverse drug events or noncompliance. Among 727 reported cases, 45% led to a major change in the prescription after contact with the physician. These results confirm that a close cooperation between physicians and pharmacists is essential for the safety and the efficiency of pharmacotherapy.

Biological parameters in major depression: effects of paroxetine, viloxazine, moclobemide, and electroconvulsive therapy. Relation to early clinical outcome

BACKGROUND

Clinical and pharmacologic studies report a relative or absolute serotonergic deficiency in major depression; however, the variability of clinical characteristics of illness has led to controversial results. In the present work, we looked for a possible relationship between i) biochemical values that indirectly reflect aminergic neurons activity and clinical characteristics and ii) their evolution and the early clinical outcome under antidepressive therapies (ATs).

METHODS

Platelet serotonin content, platelet monoamine oxydase activity, and urinary biopterins were measured in 27 depressed patients before and during four different ATs (paroxetine, viloxazine, moclobemide, or electroconvulsive therapy). Depressive symptomatology and its evolution under ATs were quantified using three clinical rating scales.

RESULTS

A severe symptomatology, high serotonin (5-HT) platelet content, and high or low urinary B could represent risk factors leading to a smaller or delayed response to an AT. Furthermore, the early improvement under ATs was negatively correlated to pretreatment 5-HT platelet content.

CONCLUSIONS

Determination of 5-HT level could be useful in the choice of an AT.

Effect of modafinil on plasma melatonin, cortisol and growth hormone rhythms, rectal temperature and performance in healthy subjects during a 36 h sleep deprivation

Modafinil is an alerting substance which has been used successfully to treat narcolepsy. Nothing is known about its effect on hormone secretions. For this purpose, eight healthy young men were enrolled in a double blind trial to test the effects of modafinil on daily plasma melatonin, cortisol and growth hormone (GH) rhythms. Blood was sampled for hormone assays, every hour during the daytime and every 30 min during the nighttime. In addition, rectal temperature and mental performances were determined during the study which comprised 3 sessions, two weeks apart: a 24 h control session including a night with sleep (S1) and two 48 h sessions S2 and S3 with a sleep-deprived night (N1) followed by a recovery night (N2). Modafinil (300 mg x 2) or placebo were randomly attributed during N1 at 22 h and 8 h. As expected, performance was improved after modafinil administration and body temperature was maintained or increased. Plasma melatonin and cortisol profiles were similar after modafinil and placebo administration. The levels observed during the recovery and the control nights (N2) displayed no difference. For GH, during both sleep deprived nights, secretion was dramatically reduced compared with the control one, although the number of secretory episodes was unchanged. These data show that the alerting property of modafinil is not related to an alteration of hormone profiles and suggest that the acute modafinil administration is devoid of short-term side-effects.

Evidence for tryptophan hydroxylase and hydroxy-indol-O-methyl-transferase mRNAs in human blood platelets

Human blood platelets were tested for the presence of mRNAs coding for tryptophan hydroxylase (TPOH) and hydroxy-indol-o-methyl-transferase (HIOMT). Total RNA was extracted from platelets (12.9 +/- 3.3 mg RNA/100 ml blood, mean +/- SEM of 6 preparations) and cDNA synthesized by reverse transcription using random hexamers, oligo-dT or TPOH- or HIOMT-specific primers, designed to amplify a 254 bp fragment for TPOH and a 301 bp fragment for HIOMT. Positive controls were performed using RNA extracted from human normal or tumoral pineal glands. The PCR products were analyzed by gel electrophoresis, transferred to a nylon membrane and hybridized with a 32P-labeled internal probe. When random hexamers, oligo-dT or specific primers were used for reverse transcription, amplification products of the predicted sizes were detectable following electrophoresis in the case of pineal glands and following transfer and hybridization in the case of platelets. These results show TPOH and HIOMT mRNAs to be present in human blood and support the hypothesis that serotonin and melatonin may be synthesized in blood and, more particularly, in platelets.

Increased serotonin platelet uptake after tianeptine administration in depressed patients

Tianeptine is a new antidepressant drug reported to enhance serotonin (5-hydroxytryptamine [5-HT]) uptake in rat brain. The effect of tianeptine on 5-HT platelet uptake was studied in 10 depressed patients treated for 28 days. Tianeptine increases Vmax of 5-HT platelet uptake during treatment without inducing any change in Km. As early as 2 hr after the first administration, Vmax increased significantly (+23%, alpha = 0.01). Although of a lesser magnitude, 5-HT platelet uptake remains increased after chronic administration (+14% on day 10 and +13% on day 28). This suggests that tianeptine affects 5-HT platelet uptake sites, either directly or via an action on modulators of 5-HT uptake. These results, in contrast with the action of other tricyclic antidepressants, confirm the original action of tianeptine on 5-HT platelet metabolism.

Distribution of alpha-1 and alpha-2 binding sites in the rat locus coeruleus

Precise anatomical distribution of alpha-1 and alpha-2 adrenergic binding sites has been investigated in the rat locus coeruleus (LC) using quantitative radioautography of brain sections incubated with 3H-prazosin or 3H-idazoxan. Distribution patterns of 3H-prazosin (alpha-1 sites) and 3H-idazoxan (alpha-2 sites) were heterogeneous and different along a postero-anterior axis in the LC. Comparison between distribution of alpha-2 binding sites and noradrenergic (NA) cellular density suggests that at least a fraction of these sites might be localized on NA perikarya or dendrites in this structure. Quantitative estimations of the binding parameters along this postero-anterior axis in the LC have revealed that the heterogeneous distributions of alpha-1 and alpha-2 binding sites are due not only to variations in the maximal densities of sites but also to variations in the affinities of these sites for their respective ligand.

Variation of tryptophan-5-hydroxylase concentration in the rat raphe dorsalis nucleus after p-chlorophenylalanine administration. II. Anatomical distribution of the tryptophan-5-hydroxylase protein and regional variation of its turnover rate

Distribution of tryptophan-5-hydroxylase (TpOH)-containing cells and TpOH protein tissue concentrations were evaluated in the nucleus raphe dorsalis (NRD) of rat brain by immunocytochemistry and direct transfer onto nitrocellulose filters of unfixed adjacent brain sections. This work has demonstrated that: (1) the direct transfer onto nitrocellulose filters could be easily used for the quantitative analysis of TpOH protein distribution; (2) the origin of the TpOH in this brain nucleus was preferentially cellular; (3) classical subdivisions, qualitatively defined from morphometric and topographic observations could be precisely described in terms of cellular density, tissue and cellular concentrations and turnover of TpOH protein. Such differences could imply a physiological control of TpOH gene expression in the serotoninergic neurons.

Biochemical evidence that brainstem adrenaline-containing neurons are activated during clonidine withdrawal in the spontaneously hypertensive rat

We have investigated the effects of prolonged treatment with clonidine (delivered intravenously via osmotic minipumps, 0.1 mg/kg/day for 7 or 10 days) and of withdrawal of such treatment on brainstem noradrenaline and adrenaline metabolism in the adult spontaneously hypertensive rat (SHR). After a seven day treatment with clonidine, noradrenaline and adrenaline turnovers were unchanged both in the A2-C2 and A1-C1 regions. During withdrawal, the noradrenaline turnover was also unchanged in these regions. However, the adrenaline turnover was significantly increased 16 h after withdrawal (p less than 0.01) in the A2-C2 region and 16 h (p less than 0.01) and 40 h (p less than 0.05) after withdrawal in the A1-C1 region. These results show that noradrenaline metabolism is unchanged both during clonidine treatment and during its withdrawal in the brainstem catecholaminergic regions analyzed. In contrast, the increases in adrenaline turnover found in the A2-C2 and A1-C1 regions suggest that the adrenergic neurons of the brainstem could be activated during clonidine withdrawal. As the adrenergic C1 neurons are a key element of the sympathetic vasopressor system, the increase in adrenaline turnover observed during withdrawal could be at the origin of the sympathetic hyperactivity found after cessation of prolonged treatment with clonidine.

Comparative responses of the central adrenaline- and noradrenaline-containing neurons after reserpine injections

The responses of the noradrenaline (NA)- and adrenaline (A)-containing neurons to a reserpine treatment have been studied in the rat brain by using biochemical indices of the neuronal activity. Three days after multiple reserpine injections, tyrosine hydroxylase activity was significantly increased in the locus coeruleus (LC), A1-C1 and C2 regions. No change in this activity was observed in the A2 region. Furthermore, the NA and A endogenous levels were markedly reduced both in NA and A cell bodies and/or terminals, suggesting a reserpine action on NA and A neurons. The NA turnover was unchanged in all the regions analyzed. Conversely, the A turnover was reduced in the LC, A2 and C2 regions and in the nucleus periventricularis of the hypothalamus. This result suggests a different degree of sensitivity and/or response of the NA and A neurons following reserpine administration.

Distribution of dopamine, noradrenaline and adrenaline in coronal sections of the rat lower brainstem

The concentration of the three major catecholamines (CAs) were determined in 500 micron thick coronal sections of the rat medulla oblongata dissected into microcubes. Noradrenaline (NA) concentrations were always found much higher than the levels of the two other CAs in the same microcube. The highest concentrations of the three CAs were found in the dorso-medial region of the lower brainstem, more exactly in the more caudally located parts of the nucleus tractus solitarii (NTS). In the ventro-lateral region, the CA concentrations were lower and, except for adrenaline (A), did not exhibit any substantial change in their rostro-caudal distribution. Conversely, in the dorso-medial region, there was a clear rostro-caudal pattern of distribution of the three CAs. This distribution was similar for the three amines, since only a small difference (about 500 micron) was found between the maximal NA and A concentrations. Since the three CAs are present in highest concentrations within the same dorso-medial or ventro-lateral groups of microcubes, a microdissection of these two areas seems suitable to study simultaneously the metabolism of the three CAs in the rat lower brainstem. These data also suggest a microdissection procedure to study A metabolism within the C2-C3 A cell bodies and within a region more caudally located, rich in A terminals.

Changes in tyrosine hydroxylase and dopamine-beta-hydroxylase activities but not in phenylethanolamine-N-methyltransferase activity within central adrenaline neurons after 6-hydroxydopamine administration

By using a new microdissection procedure allowing the noradrenaline (NA) and adrenaline (A) cell groups of the A2-C2 region to be sampled preferentially, it was possible to study the biochemical response of these two neuronal populations after 6-hydroxydopamine (6-OHDA) administration. Five days after an intraventricular 6-OHDA injection, tyrosine hydroxylase (TH) activity increased (+104%, P less than 0.01) in the adrenergic C2 region, in the locus coeruleus (LC) and in the A1-C1 region, while the NA A2 region exhibited no significant increase. Twenty-one days after 6-OHDA administration, dopamine-beta-hydroxylase (DBH) activity had decreased in both the noradrenergic regions (LC, A1-C1 and A2 regions) and in the C2 adrenergic region. Conversely, phenylethanolamine-N-methyltransferase (PNMT) activity was not modified either in the cell bodies or in the terminals located in the tractus intermediolateralis of the spinal cord and in the hypothalamic nuclei. These data suggest: (i) that adrenaline-containing neurons could be sensitive to the neurotoxic action of 6-OHDA since they exhibit changes in TH and DBH activities; and (ii) that the determination of PNMT activity may not be sensitive enough to estimate the functional integrity of the A cell bodies or terminals.

Central and peripheral catecholamine synthesizing enzymes during the development of two-kidney, one clip hypertension in rats

The activities of the catecholamine synthesizing enzymes have been determined in discrete brain areas and in peripheral tissues of rats, at different times after clipping the left renal artery (two-kidney Goldblatt hypertension, 2KGH) and in sham operated animals. Three days after clipping the only enzymatic change was a slight decrease in plasma dopamine-beta-hydroxylase (DBH) activity. Ten days after clipping no change in enzymatic activity was found at the central level. However, the DBH and the phenylethanolamine-N-methyltransferase (PNMT) activities were increased in the adrenal medulla (+49.0%, P less than 0.001 and +36.6%, P less than 0.001, respectively) and DBH activity was also increased in the superior cervical ganglia (+22.8%, P less than 0.01). These data suggest that sympathetic hyperactivity is present in 2KGH rats when hypertension is established. In addition, as this type of hypertension does not alter the PNMT activity in brainstem areas, it seems that the alterations in PNMT activity reported for genetically hypertensive rats are unlikely to be secondary to the elevated blood pressure.

Adrenaline and noradrenaline neurons in rat lower brain stem: anatomical and pharmacological neurochemistry

Since there was no study available on the comparative anatomical neurochemistry of the noradrenaline (NA) and adrenaline (A) containing neurons of the lower brain stem, we studied the distribution of the activities of the three major catecholamines (CA)-synthesizing enzymes in coronal sections of the rat medulla oblongata dissected into microcubes. In the dorso-medial region, there was a 1500 micron rostro-caudal difference in the localization of the peak of PNMT activity compared with the peaks of TH and DBH activities. This result led to a new microdissection technique allowing the preferential microdissection of the C2 A neurons versus the A2 NA neurons. The response of these two populations of CA neurons was then studied after a sustained decrease in blood pressure induced in young SHR by a 14 days dihydralazine treatment. The C2 adrenergic region exhibited an overall increase in TH, DBH and PNMT activity (+69%, +45% and +33%; p less than 0.01 respectively) while the A2 noradrenergic region was unaffected. Thus, the NA and A neurons of the rat dorso-medial lower brain stem do not seem to exhibit the same biochemical response after a prolonged hypotension. This preliminary result favors the hypothesis of a different functional role for the neighboring A2 and C2 neurons in central control of blood pressure.

Increased tyrosine hydroxylase activity in central adrenaline neurons after reserpine treatment

By using preferential microdissection of the adrenaline (A) and noradrenaline (NA) neurons within the A2-C2 region of the rat medulla oblongata, it was possible to study the biochemical response of these two neuronal populations to reserpine administration. Three days after reserpine injections (10 mg/kg s.c., per day for 3 days), tyrosine hydroxylase (TH) activity was increased in the adrenergic C2 region whilst no change was observed in the noradrenergic A2 region. The response of the A neurons to reserpine was of lesser magnitude than the increase in TH activity observed under the same conditions in the NA neurons of the locus coeruleus and of the A5 region, and was likely to have originated in the A cell bodies. In contrast with previous studies, this work suggests that the A-containing neurons are responsive to reserpine administration, despite the lack of change in phenylethanolamine-N-methyltransferase activity.

Distribution of tyrosine hydroxylase, dopamine-beta-hydroxylase and phenylethanolamine-N-methyltransferase activities in coronal sections of the rat lower brainstem

The activities of the three major catecholamines synthesizing enzymes were determined on supernatants from microcubes dissected out from 500 microns thick coronal sections of the rat lower brainstem. The microcubes exhibiting significant or high enzymatic activities represented only one-third of the microcubes analyzed and were generally localized either in the dorso-medial or in the ventro-lateral region of the lower brainstem. In the ventro-lateral region, referred to as the A1-C1 region, the rostro-caudal distribution of the enzymatic activities exhibited a small difference between the maximal TH and DBH activities and the maximum PNMT activity located 500 microns more rostrally. Conversely, in the dorso-medial region, referred to as the A2-C2 region, there was a much larger rostro-caudal difference (about 1500 microns) between the peaks of TH and DBH activities and the more rostral peak of PNMT activity. Such a distribution suggests a separation between the adrenaline (A) and the noradrenaline (NA) containing neurons within the dorso-medial region. According to the results of this study, a preferential microdissection of the A versus NA neurons seems possible in the A2-C2 region of the rat medulla oblongata.

Comparative microdistribution of the activity of catecholamine-synthesizing enzymes in horizontal sections of the rat lower brainstem

The activities of the three major catecholamine-synthesizing enzymes were determined in brain tissue pellets dissected from 500-micrometers thick horizontal sections of rat lower brainstem. The rostrocaudal distributions of the three enzymatic activities were generally not parallel, suggesting differences in the respective localization of the noradrenergic and adrenergic neurons. The difference was most important in the A2-C2 region where the maximal activity of phenylethanolamine-N-methyltransferase (EC 2.1.1.28) was located 1.5 mm more rostrally than the maximal activities of the tyrosine hydroxylase (EC 1.14.16.2) and dopamine beta-hydroxylase (EC1.14.17.1). This result indicates that a more specific dissection of the adrenergic and noradrenergic neurons could be performed in the A2-C2 area of the rat brainstem.