Journal of chemical neuroanatomy
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J. Chem. Neuroanat. · Dec 2005
Functional and ultrastructural neuroanatomy of interactive intratectal/tectonigral mesencephalic opioid inhibitory links and nigrotectal GABAergic pathways: involvement of GABAA and mu1-opioid receptors in the modulation of panic-like reactions elicited by electrical stimulation of the dorsal midbrain.
In the present study, the functional neuroanatomy of nigrotectal-tectonigral pathways as well as the effects of central administration of opioid antagonists on aversive stimuli-induced responses elicited by electrical stimulation of the midbrain tectum were determined. Central microinjections of naloxonazine, a selective mu(1)-opiod receptor antagonist, in the mesencephalic tectum (MT) caused a significant increase in the escape thresholds elicited by local electrical stimulation. Furthermore, either naltrexone or naloxonazine microinjected in the substantia nigra, pars reticulata (SNpr), caused a significant increase in the defensive thresholds elicited by electrical stimulation of the continuum comprised by dorsolateral aspects of the periaqueductal gray matter (dlPAG) and deep layers of the superior colliculus (dlSC), as compared with controls. ⋯ Labeled neurons of the midbrain tectum send inputs with varicosities to ipsi and contralateral dlSC/dlPAG and ipsilateral substantia nigra, pars reticulata and compacta, in which the anterograde and retrograde tracing from a single injection indicates that the substantia nigra has reciprocal connections with the dlSC/dlPAG featuring close axo-somatic and axo-dendritic appositions in both locations. In addition, ultrastructural approaches show inhibitory axo-axonic synapses in MT and inhibitory axo-somatic/axo-axonic synapses in the SNpr. These findings, in addition to the psychopharmacological evidence for the interaction between opioid and GABAergic mechanisms in the cranial aspects of the MT as well as in the mesencephalic tegmentum, offer a neuroanatomical basis of a pre-synaptic opioid inhibition of GABAergic nigrotectal neurons modulating fear in defensive behavior-related structures of the cranial mesencephalon, in a short link, and through a major neural circuit, also in GABA-containing perikarya and axons of nigrotectal neurons.
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J. Chem. Neuroanat. · Aug 1995
Localization of enkephalinergic neurons in the central nervous system of the salmon (Salmo salar L.) by in situ hybridization and immunocytochemistry.
The distribution of neurons expressing preproenkephalin (PPE) mRNA in the brain of the salmon was investigated by means of non-radioactive in situ hybridization, and directly compared with the distribution of enkephalin-immunoreactive (ENKir) neurons. This approach, utilized here for the first time in a non-mammalian vertebrate for the identification of neurons containing opioid peptides, permitted a detailed analysis of the distribution of putative enkephalinergic neurons in the salmon brain. Several cell groups containing neurons that express PPE mRNA also contain ENKir neurons. ⋯ The majority of these periventricular ENKir neurons were of the cerebrospinal fluid-contacting type. ENKir neurons were also located in the dorsal lateral tegmental nucleus and in area B9. The results also permitted a tentative identification of enkephalinergic neurons afferent to the optic tectum, that have previously not been identified with immunocytochemistry, located in the dorsal telencephalic area, as well as enkephalinergic neurons intrinsic to the tectum that may contribute to the laminar arrangement of ENKir fibers in the optic tectum.
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J. Chem. Neuroanat. · Nov 2013
Embryonic and postnatal development of calcium-binding proteins immunoreactivity in the anterior thalamus of the guinea pig.
Our recent studies have shown that the distribution of calretinin (CR) in the anterior thalamic nuclei (ATN) changes significantly during the development of the guinea pig. The present study was designed to reveal the distribution pattern of calcium-binding proteins, i.e. calbindin (CB) and parvalbumin (PV), as well as the colocalization pattern of all three proteins, including CR, in the ATN of guinea pigs ranging from the 40th embryonic day (E40) to the 80th postnatal day (P80). According to these patterns, CB appears exclusively in the perikarya of the anteromedial nucleus (AM) not before P20 and always colocalizes with CR. ⋯ In conclusion, our study reveals that the distribution of the studied proteins differs greatly. Nevertheless, the postnatal coexistence of CB and CR in the AM perikarya may indicate the cooperation of both of the proteins in some functions of the nucleus. Parvalbumin is limited mostly to the neuropil of the AD, suggesting different functions in comparison to CB and CR.
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J. Chem. Neuroanat. · Jun 1997
Localization of two cholinergic markers, choline acetyltransferase and vesicular acetylcholine transporter in the central nervous system of the rat: in situ hybridization histochemistry and immunohistochemistry.
Choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) are proteins that are required for cholinergic neurotransmission. Present knowledge concerning the organization of cholinergic structures has been derived primarily from immunohistochemistry for ChAT. In the present study, we investigated the distribution of mRNAs and the corresponding proteins for ChAT and VAChT by in situ hybridization histochemistry and immunohistochemistry. ⋯ In the forebrain, they were present in the olfactory bulb, nucleus of the lateral olfactory tract, olfactory tubercle, lateral septal nucleus, amygdala, hippocampus, neocortex, caudate-putamen, thalamus and median eminence of the hypothalamus. In the brainstem, they were localized in the superior colliculus, interpeduncular nucleus and some cranial nerve motor nuclei, and further in the ventral horn of the spinal cord. These results indicate strongly that ChAT and VAChT are expressed in most of the cholinergic neurons, and that immunohistochemistry for VAChT is as useful to detect cholinergic terminal fields as that for ChAT.
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J. Chem. Neuroanat. · Jan 2013
Developmental changes of calretinin immunoreactivity in the anterior thalamic nuclei of the guinea pig.
This study describes for the first time the distribution of the calcium-binding protein calretinin (CR) in the anterior thalamic nuclei (ATN) of the guinea pig during development. Brains from animals ranging from 40th embryonic day (E40) to 80th postnatal day (P80) were used in the study. No CR-immunoreactive (CR-ir) perikarya were present among the ATN at E40, but thick bundles of fibers containing CR were crossing the anteromedial nucleus (AM). ⋯ The ATN of newborns (P0) already showed an adult-like CR distribution pattern - perikarya in the AM and AV were distributed more homogenously and their number was slightly decreased in comparison to E60. The anterodorsal nucleus (AD) was devoid of CR-ir neurons in all studied stages. In conclusion, our results demonstrate that calretinin appears for the first time in neurons of various anterior thalamic nuclei of the guinea pig between 40th and 60th day of prenatal development.