Changes in oestrogen receptor alpha expression in the nucleus of the solitary tract of the rat over the oestrous cycle and following ovariectomy

Oestrogen is capable of modulating autonomic outflow and baroreflex function via actions on groups of neurones in the brainstem. We investigated the presence of oestrogen receptor (ER) alpha in a part of the nucleus of the solitary tract (NTS) associated with central cardiovascular control, aiming to determine whether ERalpha mRNA and protein expression is correlated with levels of circulating oestrogen during the oestrous cycle. Polymerase chain reaction (PCR) detected ERalpha mRNA in the NTS at each stage of the oestrous cycle, from ovariectomised, sham-operated and male rats. Real-time PCR showed variations in ERalpha mRNA expression during the oestrous cycle, with the highest levels seen in oestrus, and lowest levels in metoestrus (P < 0.05 versus oestrus) and proestrus (P < 0.05 versus oestrus). Expression in males was lower than in dioestrus and oestrus females (P < 0.05). After ovariectomy, ERalpha mRNA levels were decreased compared to sham-operated animals (P < 0.01). Confocal fluorescence immunohistochemistry with stereological analysis showed that numbers of ERalpha immunoreactive cell nuclei per mm(3) of tissue in the caudal NTS were significantly greater in proestrus than in other groups of rats (P < 0.05). There were also differences among the groups in the extent of colocalisation of ERalpha in neurones immunoreactive for tyrosine hydroxylase and nitric oxide synthase. These results imply a complex pattern of region-specific oestrogen signalling in the NTS and suggest that ERalpha expression in this important autonomic nucleus may be related to circulating oestrogen levels. This may have consequences for the regulation of autonomic tone and baroreflex sensitivity when oestrogen levels decline, for example following menopause.

[Identification and expression of six drought responsive transcripts through differential display in desi cottion (Gossypium aroreum)]

There is not enough information available on drought-modulated gene(s) in Gossypium arboreum, which can be a valuable gene pool for improving modern cotton cultivars. In the present work differential display reverse transcriptase PCR (DDRT) was used to compare overall differences in gene expression between water stressed and control plants. By screening 93 primer-pair combinations DDRT technique resulted in up-regulation of 30 cDNA transcripts. Through reamplification and quality control assay 10 cDNA transcripts appeared false positive. The remaining 20-cDNA transcripts were extracted from the gel, reamplified, cloned and sequenced. Homology search revealed that 6 transcripts showed significant homology with known genes. Real-time RT-PCR showed that among 6 transcripts 5 showed significant over expression in water stressed leaves as compared to control. This is an important finding since there are only few reports of universal stress protein and transposable elements are available in plants but none in cotton under drought condition.

Effect of a common X-linked angiotensin II type 2-receptor gene polymorphism (-1332 G/A) on the occurrence of premature myocardial infarction and stenotic atherosclerosis requiring revascularization

OBJECTIVES

To assess the association of the angiotensin II type 2 (AT2) receptor (-1332 G/A) gene polymorphism with premature coronary artery disease (CAD) and investigate for a further role in both myocardial infarction and predominantly stenotic atherosclerosis requiring revascularisation.

METHODS AND RESULTS

We investigated 885 families, which consisted of at least one sibling affected with premature CAD and at least one unaffected sibling. Genotyping of subjects was performed using a restriction enzyme digestion of an initial 310 bp PCR fragment that included the AT2 (-1332 G/A) locus. The mean age of the 1143 individuals affected by premature CAD at the time of event was 50.6+/-9.1 years. The genetic data were analyzed for these families using the X-linked sibling transmission disequilibrium test (XS-TDT). We observed significant evidence for an association for the AT2 (-1332 G) locus and premature CAD (p-exact value=0.028). This was driven by a highly significant result in men (p-exact value=0.005). We performed further analyses to investigate for an association with myocardial infarction (Group 1) and stenotic atherosclerosis that was of sufficient severity as to require revascularization (Group 2). We found an increase in the frequency of the G/GG genotype in both Groups 1 and 2, being most marked in Group 2 (XS-TDT, p-exact value=0.0134); logistic regression (p=0.033, OR 1.38; 95% CI of 1.212-1.507).

CONCLUSION

We have observed evidence of association between the X-linked AT2 (-1332 G/A) polymorphism and premature CAD with further evidence of a statistically significant association with stenotic atherosclerosis requiring revascularization.

An evaluation of the beta-1 adrenergic receptor Arg389Gly polymorphism in individuals at risk of coronary events. A WOSCOPS substudy

AIMS

The Glycine389 variant of the beta-1 adrenergic receptor generates markedly less cAMP when stimulated in vitro than the more prevalent Arginine389 variant and may confer protection against coronary events similar to that observed with beta-blockers. The aim of this study was to ascertain whether this Glycine389 variant protects against coronary events.

METHODS AND RESULTS

We identified the genotype at position 389 of the beta1AR in 1554 individuals taken from men enrolled in the West of Scotland Coronary Prevention Study. Men with a coronary event (event group) were each matched for age and smoking status with two control subjects from the same cohort who had not had a coronary event (control group). We compared the distribution of genotypes in the event and control groups. Conditional logistic regression was used to calculate odds ratios for each of the genotypes. The prevalence of the three genotypes in the entire cohort was ArgArg 53.5%, ArgGly 39.6%, GlyGly 6.9%. The Arg389Gly beta-1 adrenergic receptor polymorphism was not associated with coronary events. Using the ArgArg genotype as the reference, the odds ratio for the ArgGly genotype was 1.1 (95% CI, 0.88-1.38) and for the GlyGly genotype it was 1.05 (95% CI, 0.68-1.62).

CONCLUSION

Our longitudinal case-control study demonstrates that the Glycine389 variant of the beta-1 adrenergic receptor does not protect against coronary events.

Protection of bronchoalveolar macrophages by granulocyte-macrophage colony-stimulating factor against dexamethasone suppression of fungicidal activity for Aspergillus fumigatus conidia

The objectives of this study were to: (i) see if granulocyte macrophage colony-stimulating factor (GM-CSF) could protect bronchoalveolar macrophages (BAM) against suppression by dexamethasone (DEX) and (ii) test the combined effect of GM-CSF and DEX on lymphocyte responses. Murine BAM killed Aspergillus fumigatus conidia by 33 +/- 4% (mean +/- SD) in a 2.5-h assay, unaffected by GM-CSF treatment. Killing by BAM treated with DEX (10(-7) M) for 48 h in vitro was reduced to 13 +/- 6%; however, if GM-CSF (500 U ml(-1)) was present during DEX treatment of BAM, killing of conidia (33 +/- 2%) by BAM was preserved. By contrast, DEX suppression of lymphocyte responses to concanavalin A was maintained during co-culture with GM-CSF. In sequence treatment experiments, initial treatment of BAM with GM-CSF protected against subsequent treatment with DEX. When macrophages were pretreated with DEX, GM-CSF could reverse suppression even when added subsequently, provided DEX treatment was discontinued. These data suggest that it may be possible to suppress lymphocyte responses with DEX, yet at the same time maintain BAM defenses with GM-CSF against pulmonary infections by conidia of A. fumigatus.

In vivo GM-CSF prevents dexamethasone suppression of killing of Aspergillus fumigatus conidia by bronchoalveolar macrophages

Dexamethasone (DEX) is a potent immunosuppressive agent used in the treatment of several disorders. However, despite its beneficial effects, DEX puts patients at risk for opportunistic infections, especially pulmonary aspergillosis. Previously we reported that in vitro granulocyte-macrophage colony-stimulating factor (GM-CSF) blocks the immunosuppressive action of DEX on bronchoalveolar macrophages (BAMs). Here we report that BAMs freshly isolated from mice treated intraperitoneally with DEX for 24 h had significantly (P<0.01) reduced killing of conidia, i.e., 15 +/- 5% conidia killed by BAMs from DEX-treated mice versus 35 +/- 3% by BAMs from mice given saline, 38 +/- 5% by BAMs from mice given GM-CSF, and 39 +/- 1% by BAMs from mice given both DEX and GM-CSF. On the other hand, in another compartment GM-CSF could not block the DEX reduction of spleen weight and spleen cellularity. Unlike GM-CSF, granulocyte colony-stimulating factor did not block DEX suppression of BAMs. GM-CSF given 24 h before DEX resulted in blocking of DEX suppression of BAM conidiacidal activity. However, when DEX was given 24 h before GM-CSF, DEX suppression of BAM was not reversed. These data show that GM-CSF in vivo blocks the in vivo immunosuppressive effects of DEX on BAM killing of conidia and suggest a potential use of GM-CSF in patients at risk for aspergillosis due to immunosuppressive DEX treatment.

Co-localization of c-Fos and neurotransmitter immunoreactivities in the cat brain stem after carotid sinus nerve stimulation

To reveal neurones in the cat medulla oblongata involved in carotid baroreceptor/chemoreceptor reflexes, the distribution of c-Fos oncoprotein immunoreactivity was studied following electrical stimulation of the right carotid sinus nerve. The neurochemistry of the activated neurones was investigated using antisera to tyrosine hydroxylase, neuropeptide Y, somatostatin, and glutamate. Nitric oxide containing neurones were identified using antiserum to nitric oxide synthase (NOS) and by the histochemical localization of nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase. Following sinus nerve stimulation numerous c-Fos-IR cells were detected both ipsilaterally and contralaterally in the nucleus tractus solitarii, the area postrema and throughout the ventrolateral medulla. Dual labelling studies revealed that 3.3% of c-Fos-immunoreactive cells in the nucleus tractus solitarii were also immunoreactive for tyrosine hydroxylase. The double labelled cells were scattered within the medial and ventrolateral subnuclei, predominantly rostral to obex. A higher proportion (10.3%) of c-Fos-IR cells in the ventrolateral medulla also showed tyrosine hydroxylase immunoreactivity. Caudal to obex, these were scattered in the reticular formation between the spinal trigeminal nucleus and the lateral reticular nucleus, while more rostrally they were found within the lateral reticular nucleus, the nucleus ambiguus and the lateral tegmental field. Cells expressing c-fos and reactive for glutamate, neuropeptide Y or NADPH-diaphorase (or NOS) were only rarely seen, and co-localization of c-Fos and somatostatin immunoreactivities was not seen. These results suggest that of the neurones forming pathways within the medulla activated on carotid sinus nerve stimulation, presumably mediating baro- and chemoreceptor reflexes, relatively few utilize catecholamines, glutamate, neuropeptide Y or nitric oxide as their transmitter substance.

Influence of peripheral targets on the expression of calcitonin gene-related peptide immunoreactivity in rat cranial motoneurones

Calcitonin gene-related peptide-like immunoreactivity (CGRP-ir) is displayed by motoneurons that innervate striated muscle but is absent from preganglionic parasympathetic motoneurons. One hypothesis to explain this is that CGRP gene expression in motoneurons is, in part, dependent on influences from the innervated organ. To test this hypothesis, we cross-anastomosed the right hypoglossal and cervical vagal nerves of rats so that the vagal motoneurons grew to innervate the musculature of the tongue. Following a recovery period of 17 to 52 weeks, the distribution of CGRP-ir in the dorsal motor vagal nucleus was determined in both cross-anastomosed animals and self-anastomosed control animals. Successful reinnervation of the tongue musculature by vagal motoneurons was demonstrated by showing that electrical stimulation of the central vagus/peripheral hypoglossal nerve produced a twitch of the tongue muscles. Motoneurones of the dorsal motor vagal nucleus, which now innervated the tongue were found to express CGRP-ir, which was evident from the double labeling of neurons with both horseradish peroxidase and CGRP-ir. Motoneurones of the dorsal motor vagal nucleus contralateral to the cross-anastomosis remained CGRP negative. Similarly, motoneurons of the dorsal motor vagal nucleus in control animals where the vagus nerve was self-anastomosed remained CGRP negative, showing that an induction of CGRP expression is not a result of nerve section itself. We suggest that a signal from the striated muscle transported retrogradely via the motor axon regulates expression of CGRP-ir in motoneurons.

Co-localization of neurotransmitter immunoreactivities in putative nitric oxide synthesizing neurones of the cat brain stem

The distribution of nitric oxide producing neurones in the medulla oblongata of the cat was investigated using nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry, and nitric oxide synthase (NOS) immunohistochemistry. The pattern of staining obtained with both methods was found to be similar. Strongly diaphorase and NOS reactive neurones were present in the paramedian and lateral tegmental fields, including the regions occupied by the A1/C1 catecholamine cell groups, the nucleus ambiguus and lateral reticular nucleus, and in a number of sensory nuclei including the nucleus of the tractus solitarius and the dorsal column nuclei. The extent of co-localization of NADPH-diaphorase with a number of neuropeptides and neurotransmitters was investigated by combining NADPH-diaphorase histochemistry with immunocytochemistry for neuropeptide Y, somatostatin, glutamate, cholecystokinin and tyrosine hydroxylase. NADPH-diaphorase reaction product was observed in neurones immunoreactive for glutamate and somatostatin. These double-labelled cells were found in the paramedian region, lateral reticular field, the nucleus prepositus hypoglossi and in the rostral nucleus of the tractus solitarius. In the rostral ventrolateral medulla NADPH-diaphorase/somatostatin immunoreactive cells were found in the paragigantocellular nucleus. NADPH-diaphorase/glutamate immunoreactive cells overlapped the nucleus ambiguus, the lateral reticular nucleus and the A1/C1 catecholaminergic cell groups. In addition, a few NADPH-diaphorase/glutamate immunoreactive cells were found in the paraolivary area and gigantocellular tegmental field, in the external cuneate and infratrigeminal nuclei. The functional implications of the co-localization of nitric oxide with these neurotransmitters in areas of the medulla concerned with cardiovascular regulation is discussed.

Distribution of dopamine-containing neurons and fibres in the feline medulla oblongata: a comparative study using catecholamine-synthesizing enzyme and dopamine immunohistochemistry

The distribution of dopamine-immunoreactive neurons and fibres in the feline medulla oblongata was examined by immunocytochemistry with antisera to the catecholamine-synthesizing enzymes tyrosine hydroxylase, dopamine-beta-hydroxylase and phenylethanolamine-N-methyltransferase, and with antisera to the catecholamines dopamine and L-dihydroxyphenylalanine. Neurons immunoreactive for the catecholamine-synthesizing enzymes were found in two regions of the medulla, the ventrolateral A1 region and the dorsomedial A2 region. Double-staining studies with antisera to the enzymes indicated that a population of neurons within both regions were immunoreactive for tyrosine hydroxylase but not dopamine-beta-hydroxylase or phenylethanolamine-N-methyltransferase, implying that they synthesize dopamine. Studies using the dopamine antisera demonstrated the presence of dopamine-immunoreactive neurons in both the ventrolateral and dorsomedial regions of the medulla; in the dorsomedial region, they were found in the area postrema, nucleus tractus solitarius and dorsal motor vagal nucleus, mainly at levels caudal to the obex. Dopamine-immunoreactive fibres were found in several areas of the medulla including the nucleus tractus solitarius, inferior olive, dorsal motor vagal, spinal trigeminal, hypoglossal, cuneate, gracile, and raphe nuclei. Double-staining studies with antisera to dopamine and dopamine-beta-hydroxylase revealed a population of cells immunoreactive for dopamine alone. The presence of some double-stained neurons, however, implies some cross-reactivity of the dopamine antiserum with noradrenaline or adrenaline and/or recognition of dopamine present as a metabolic intermediary in some noradrenergic neurons. No L-dihydroxyphenylalanine-immunoreactive neurons were found in the medulla, although fibres were seen. These data provide evidence for the existence of catecholamine neurons which utilize dopamine as a final synthetic product within the medulla oblongata.

Immunolocalization of catecholamine enzymes, serotonin, dopamine and L-dopa in the brain of Dicentrarchus labrax (Teleostei)

Antisera to serotonin (5-HT), dopamine, and L-dopa, and to the catecholamine synthesizing enzymes, tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyl transferase (PNMT), were used to localize monoamine containing neurones in the brain of Dicentrarchus labrax (sea bass). In the brain stem, 5-HT-immunoreactive (ir) neurones were recognized in the ventrolateral medulla, vagal motor area, medullary, and mesencephalic raphe nuclei and in the dorsolateral isthmal tegmentum. In the hypothalamus, liquor-contacting 5-HT neurones were seen in various regions of the paraventricular organ. Virtually all regions of the brain contained a dense innervation by 5-HT fibres and terminals. DBH-ir neurones were restricted to three brain stem areas: the locus coeruleus, the area postrema, and the reticular formation of the lower medulla. Neurones in these three groups also displayed TH-ir, and in the latter area, PNMT-ir in addition. In the locus coeruleus and area postrema, TH-ir neurones outnumbered DBH-ir neurones, an observation substantiated by the presence of dopamine-ir neurones. In the forebrain, dopamine- and TH-ir neurones were found in the olfactory bulb, ventral/central telencephalon, periventricular preoptic, and suprachiasmatic areas, dorsolateral and ventromedial thalamus, and posterior tuberal nucleus. In the paraventricular organ, the distribution and morphology of dopamine-ir neurones was similar to that observed with anti-5-HT, but the vast majority of cells were not TH-ir, suggesting accumulation of dopamine by uptake from the ventricle, rather than by synthesis. L-dopa-ir neurones were found only in the central telencephalon, preoptic recess, and dorsolateral thalamus. Fibres and terminals immunoreactive for dopamine, TH, and DBH showed a broadly similar distribution. The results are discussed in relation to the monoaminergic systems previously reported in other teleostean species and the mammalian brain.