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Biomedical subjects

M Geffard

Publications and source records attributed to M Geffard.

198 records · Page 11Linked to original sources
PubMed1984

Antibodies to dopamine: radioimmunological study of specificity in relation to immunocytochemistry.

Two classes of anti-3,4- dihydroxyphenylethylamine (dopamine) antibodies were raised in rabbits using dopamine conjugated to albumin either via formaldehyde or via glutaraldehyde. Each was usable for immunohistochemical detection of dopamine neurons provided that the tissue was fixed by the homologous cross-linking agent. However, anti-dopamine-glutaraldehyde antibodies turned out to be of more general use because of the better fixative properties of glutaraldehyde which fixed dopamine in rat and in teleost, whereas formaldehyde only worked in lower vertebrates (such as goldfish) and not in rat brain. The specificity of anti-dopamine-glutaraldehyde antibodies was firmly established by competition experiments in equilibrium dialysis, using an immunoreactive tritiated derivative synthesized by coupling dopamine to N-alpha-acetyl-L-lysine N-methylamide via glutaraldehyde. Specificity studies in vitro and immunohistological results demonstrating the specific staining of dopaminergic neurons were found to correlate well.

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PubMed1984

Immunocytochemical localization and circadian variations of serotonin and N-acetylserotonin in photoreceptor cells. Light and electron microscopic study in the teleost pineal organ.

Using two immunocytochemical procedures (i.e., immunofluorescence and the unlabeled peroxidase-antiperoxidase method), the localization of a serotonin(HT)-like and of a N-acetylserotonin (aHT)-like immunoreactivity in the pineal organ of the pike was studied during winter. It was shown that immunostaining was exclusively restricted to the cells of the receptor line (CRL = typical and modified photoreceptors). The intensity of the reactions varied through the light-dark cycle, HT-like immunoreactivity being high during the photophase and low during the scotophase. In contrast, aHT-like immunoreactivity was highest at the beginning of the scotophase. HT and aHT-like immunoreactivities were detected in all cell types of the pineal epithelium after administration of a monoamine oxidase inhibitor. Up to now, only HT immunoreactivity could be localized at the ultrastructural level. In a number of typical and modified photoreceptors, a HT-positive staining seemed to be confined within the hyaloplasm of the inner segment, particularly with that of the perikaryon and basal pedicle. Our previous and present results strongly suggest that indole compounds, which are involved in the regulation of various neuroendocrine processes in fish, are synthetized within the CRL. Taking into account that the CRL of the pike are also photosensitive, it appears more and more likely that they are photoneuroendocrine cells involved in mediating the effects of the photoperiod on various physiological and behavioral processes.

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PubMed1982

[1st immunocytochemical application of an anti-dopamine antibody in the study of the central nervous system].

An antibody against dopamine was raised in Rabbits by means of an immunogen constituting dopamine coupled to bovine serum albumin by formaldehyde. These antibodies were applied to frozen sections of Goldfish (Carassius auratus) brain fixed by 4% paraformaldehyde. The localisation of immunoreactive structures corresponded to regions rich in dopamine detected by histofluorescence. The specificity of this antiserum tested with the aid of dopamine analogues coupled with a carrying protein different from that of the antibody, indicates its validity as a method for the detection of dopaminergic neurons.

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PubMed1982

Central administration of arginine vasotocin: effects on exploratory behavior in the rat.

Synthetic arginine vasotocin (AVT) was infused into rat brains either by intraventricular administration or by local infusion on the pineal body. Subsequently, exploratory behavior was analyzed in a hole board. The behavioral effects induced by this peptide were dependent on the time of day, i. e. the light or the dark phase. High intraventricular doses (0.4 microgram) administered during the light phase altered exploratory activity such that the number of hole visits was increased, while the duration of each visit was decreased; lower doses produced no effect. In contrast, during the dark phase peripineal infusion of AVT (10(-4) pg) attenuated the number of hole visits and increased the mean duration of the visits. The strongest effects were obtained with peripineal applications during the dark phase. This treatment also resulted in significantly lowered levels of pineal melatonin.

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PubMed1982

[Melatonin in the pineal organ, retina and plasma. Immunologic study in the pigeon].

Circadian variations in melatonin content have been studied in the pineal organ, retina and plasma of adult pigeons using radioimmunoassay. A clear-cut peak of melatonin was observed in the pineal organ at middark; this middark peak was of larger amplitude in July than in November. A nocturnal rise in melatonin concentration was also observed in the retina and plasma. We also used an immunocytochemical technique revealing the positive reactions of a melatonin-like compound in the photoreceptor cell layer (inner segments) of the pigeon's retina. Up to now, no melatonin storage has been visualized in the pineal organ of the pigeon.

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PubMedDate not supplied

des-Tyr1-gamma-endorphin and haloperidol increase pineal gland melatonin levels in rats.

The effect of subcutaneously injected DT gamma E (beta-endorphin, (beta E)2-17) on the pineal melatonin level was compared with that of closely related peptides and the neuroleptic drug haloperidol. As found previously, DT gamma E (3 ng/rat and 300 ng/rat) increased the melatonin levels. Similar doses of DT alpha E (beta E 2-16), DT beta E (beta E 2-31), gamma E (beta E 1-17), alpha E (beta E 1-16) and beta E failed to significantly change the melatonin levels in both the dark and the light phase. Haloperidol in a dose of 300 ng/rat exhibited a similar effect as DT gamma E.

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PubMedDate not supplied

Glycine immunoreactivity in the brainstem auditory and vestibular nuclei of the guinea pig.

An immunohistochemical study was performed on the brainstem of the guinea pig, using a specific antibody against glycine. Glycine-like immunoreactivity was observed in stellate and multipolar neurons in the cochlear nucleus, in the medial and lateral nuclei of the trapezoid body and in the ventromedial periolivary cell group. No immunoreactive neurons were found in the vestibular nuclei. Positive fibre tracts were observed mainly in dorsal acoustic stria and lateral lemniscus. The results are consistent with electrophysiological and anatomical data from the literature concerning the response pattern in the fusiform layer of the dorsal cochlear nucleus and the phenomenon of binaural inhibition in the superior olivary complex.

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PubMedDate not supplied

Evidence for the existence of L-dopa- and dopamine-immunoreactive nerve cell bodies in the caudal part of the dorsal motor nucleus of the vagus nerve.

The precise neurochemical nature of tyrosine hydroxylase-immunoreactive neurons lying in the caudal part of the dorsal motor nucleus of the vagus nerve of the rat has been identified by immunohistochemistry of the catecholamines themselves. This region corresponds precisely to the area where tyrosine hydroxylase has been previously shown to be colocalized with choline acetyltransferase. Adjacent serial cryostat sections from the medulla oblongata and from the cervical spinal cord were treated either for choline acetyltransferase immunohistochemistry, aromatic L-amino acid decarboxylase and tyrosine hydroxylase immunolabelling or for tyrosine hydroxylase, dopamine, noradrenaline and L-dihydroxyphenylalanine (DOPA) immunostaining. The procedure involved the peroxidase-antiperoxidase method and an intensified diaminobenzidine reaction with imidazole. While no noradrenaline-positive cells were detectable in the dorsal motor vagal nucleus, tyrosine hydroxylase-, dopamine- and DOPA-immunoreactive perikarya were seen in the medial half of this nucleus, caudally the obex level. These results led us to conclude that these tyrosine hydroxylase-positive cells were effectively of dopaminergic nature and therefore that dopamine is a neurotransmitter contained in some neurons of the dorsal motor vagal nucleus. In the light of previous data showing colocalization of tyrosine hydroxylase and choline acetyltransferase in neurons of this portion of the nucleus, colocalization of dopamine with acetylcholine appears most likely. This might shed some light on the physiological consequences of dopamine action at target parasympathetic organs, such as the gastrointestinal tract.

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PubMedDate not supplied

Distribution of dopamine immunoreactive systems in brain stem and spinal cord of the chameleon.

An immunohistochemical method, using glutaraldehyde fixation and a highly specific monoclonal antibody recently synthetized against dopamine (DA)-glutaraldehyde protein conjugate, permitted direct visualization of DA structures in the brainstem and spinal cord of a reptile (Chameleon). DA-immunoreactive cell bodies occurred in some contiguous areas of the midbrain tegmentum. The first one was located in the ventral tegmental area. Some somata intermingled with the oculomotor nucleus. The second group was the large round or oval DA-Immunostained neurons located in the substantia nigra. More caudally, a third group of round or fusiform DA-cell bodies was seen in an homologous area of so called mammalian A8 and were continuous with the substantia nigra group. In the medulla oblongata, the DA-containing cells were shown in the nucleus of solitary tract and in the dorsal lateral part of the dorsal motor nucleus of the vagus. The density of this DA-Immunoreactive neurons decreased more caudally. At the medullo-spinal level and upper cervical spinal cord, a few labelled cells were distinguished near the central canal. In the spinal cord DA-immunopositive cell bodies were observed in the vicinity of the central canal and formed a continuous column that extended throughout the rostral spinal cord. The apical processes of these neurons seemed to be in contact with the lumen of the central canal. This study constitute the first visualization of the immunoreactive DA-cell bodies at the medullo-spinal level which were already described, as TH immunoreactive in other species of reptiles.

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PubMedDate not supplied

The response of noradrenergic axons to systemically administered DSP-4 in the rat: an immunohistochemical study using antibodies to noradrenaline and dopamine-beta-hydroxylase.

The response of noradrenaline (NA) axons to the effects of systemic injections of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) was studied in the rat brain. Antibodies to NA and to dopamine-beta-hydroxylase (DBH) were employed to assess by immunohistochemistry the effects of DSP-4 on NA axons between 6 h and 2 weeks after drug administration. The changes in NA and DBH staining after DSP-4 treatment were restricted to brain regions innervated by the locus coeruleus. In these areas, DSP-4 induced profound loss of both NA and DBH from NA axons, but with a distinctly different time-course. While NA disappeared within hours after drug treatment, DBH staining of NA axons remained unchanged during the first 4 days after DSP-4 treatment. Thereafter, there was an abrupt loss of DBH staining which coincided with the appearance of numerous brightly stained, thick and swollen NA axons. The distribution of these fibres suggests that they represent the distal ends of preterminal NA axons. Two weeks after drug treatment, NA axons could no longer be visualized by either NA or DBH immunohistochemistry in regions affected by DSP-4. During this 2-week time-period, the staining of cell bodies in the locus coeruleus and of ascending NA axons in the dorsal bundle was unaffected. The results suggest two phases in the response of NA axons to DSP-4: an acute phase, marked by loss of transmitter, and a neurodegenerative phase, characterized by loss of DBH and structural disintegration of NA axons.

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PubMedDate not supplied

[Simultaneous detection of tryptamine and dopamine in the substantia nigra and raphe nuclei in rats using specific antibodies].

Using a double-labelling procedure, morphological relationships existing between dopaminergic and indoleaminergic neuronal systems in rat brain were investigated. Firstly, thanks to a tryptamine (T) antiserum, we visualized this indoleamine in all mesencephalic regions and showed that the T-immunoreactivity (IR) seems to overlap with the staining observed from serotonin (HT) and 5-methoxytryptamine (MT) antisera. Secondly, using a monoclonal anti-dopamine (DA) antibody and our anti-T antibodies, the simultaneous and specific detection of these compounds enabled us to define the chemically relationships existing between the dopaminergic and tryptaminergic neuronal systems from substantia nigra to raphe nuclei. No co-localization exists. But, the intensity of T-IR decreases from the back to the front, whereas the DA-staining decreases in the opposite way, indicating possible interactions at the end of substantia nigra and B9 area.

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PubMedDate not supplied

Do tyrosine hydroxylase-immunoreactive neurons in the ventrolateral arcuate nucleus produce dopamine or only L-dopa?

Dopamine (DA) was early demonstrated in the arcuate nucleus by means of the formaldehyde-induced histofluorescence method. In the present study we have investigated the distribution of cell bodies in the arcuate nucleus with antisera against tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC) and DA. The results indicate that TH-immunoreactive cells in the dorsomedial part of the arcuate nucleus also contain immunoreactivity for both AADC and DA. However, TH-positive cells in the ventrolateral arcuate nucleus lacked AADC- and DA-immunoreactivity with the sensitivity of the present methods. The findings raise the question whether the ventrolateral cells synthesize L-DOPA or DA as endproducts.

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PubMedDate not supplied

Monoclonal anti-idiotypic antibodies as probes for common idiotopes shared by anti-"benzo(a)pyrene-like" IgA of cancer patients and rabbit anti-conjugated benzo(a)pyrene antibodies.

Anti-"benzo(a)pyrene [B(a)P]-like" IgA [referred as idiotypic antibodies (Abl)] from cancer patients' sera were found to react with conjugated B(a)P and a monoclonal anti-anti-conjugated B(a)P, internal image of conjugated B(a)P called AIB1 (referred to as Ab2 beta). These IgA were used to raise mouse monoclonal anti-idiotypic antibodies (Ab2). A monoclonal Ab2 called AIK1 was characterized as the internal image of a "B(a)P-like" structure. As shown by competitive experiments, AIK1 inhibited the reaction between Ab1 from a rabbit anti-conjugated B(a)P serum- and its relevant internal image, AIB1. Furthermore, AIB1 inhibited the reaction between AIK1 and anti-"B(a)P-like" IgA from cancer patients' sera. These observations confirmed the cross-reactivity between idiotypic determinants of human anti-"B(a)P-like" IgA and rabbit anti-conjugated B(a)P antibodies (Ab). This result was reinforced by a correlation between the anti-"B(a)P-like" IgA levels found in cancer patients' sera using indirect ELISA method with conjugated B(a)P, AIB1 and AIK1 coated on well-plates.

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