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A J Beitz

Publications and source records attributed to A J Beitz.

102 records · Page 6Linked to original sources
PubMed1982

The nuclei of origin of brainstem serotonergic projections to the rodent spinal trigeminal nucleus.

The origins of the serotonergic projections to the spinal trigeminal nucleus in the rat were determined utilizing the combined HRP retrograde transport-immunohistochemical technique. The areas providing the greatest number of serotonergic afferent projections to the spinal trigeminal nucleus are the raphe magnus, raphe obscurus, nucleus reticularis gigantocellularis pars alpha, and the nucleus reticularis paragigantocellularis. A smaller serotonergic input to the spinal trigeminal nucleus was found to arise from the raphe pallidus, periaqueductal gray, raphe dorsalis, raphe pontis and mesencephalic reticular formation. These results indicate that the spinal trigeminal nucleus receives serotonergic input from all levels of the brainstem including the midbrain cell group B7.

Afferent Pathways↗
PubMed1982

The nuclei of origin of brain stem enkephalin and substance P projections to the rodent nucleus raphe magnus.

The sites of origin of brain stem enkephalin and substance P projections to the rodent nucleus raphe magnus were studied utilizing the combined horseradish peroxidase retrograde transport-peroxidase-antiperoxidase immunohistochemical technique. Several brain stem areas were found to contain both enkephalin- and substance P-like immunoreactive double labeled neurons following injection of horseradish peroxidase into the raphe magnus. Nuclei providing both enkephalin and substance P inputs to the raphe magnus include the nucleus reticularis paragigantocellularis, the nucleus cuneiformis, the nucleus solitarius and the trigeminal subdivision of the lateral reticular nucleus. Enkephalin projections to the raphe magnus were also found to originate from the dorsal parabrachial nucleus, the nucleus reticularis gigantocellularis pars alpha and from an area which corresponds to the A5 group of Dahlström & Fuxe. Additional neurons containing substance P-like immunoreactivity and horseradish peroxidase reaction product were identified in the superior central raphe nucleus and the nucleus pontis oralis. The midbrain periaqueductal gray contributes very few enkephalin and substance P fibers to the raphe magnus. The nucleus raphe magnus is a key structure in the intrinsic analgesia system and it has also been implicated in other diverse and non-nociceptive functions. The present study identifies several brain stem sites which provide enkephalin and substance P input to this raphe nucleus. Several of these nuclei have been implicated in central analgesic mechanisms or in non-nociceptive autonomic functions. The present investigation raises the possibility that these brain stem regions may modulate neuronal activity in the raphe magnus via enkephalin or substance P projections and thus influence the involvement of the raphe magnus in both opiate related mechanisms of pain control and non-nociceptive functions.

Animals↗
PubMed1982

The organization of afferent projections to the midbrain periaqueductal gray of the rat.

The retrograde transport technique was utilized in the present study to investigate the afferent projections to the periaqueductal gray of the rat. Iontophoretic injections of horseradish peroxidase were made into the periaqueductal gray of 22 experimental animals and into regions adjacent to the periaqueductal gray in 6 control animal. Utilization of the retrograde transport method permitted a quantitative analysis of the afferent projections not only to the entire periaqueductal gray, but also to each of its four intrinsic subdivisions. The largest cortical input to this midbrain region arises from areas 24 and 32 in the medial prefrontal cortex. The basal forebrain provides a significant input to the periaqueductal gray and this arises predominantly from the ipsilateral lateral and medial preoptic areas and from the horizontal limb of the diagonal band of Broca. The hypothalamus was found to provide the largest descending input to the central gray. Numerous labeled cells occurred in the ventromedial hypothalamic nucleus, the lateral hypothalamic area, the posterior hypothalamic area, the anterior hypothalamic area, the perifornical nucleus and the area of the tuber cinereum. The largest mesencephalic input to the periaqueductal gray arises from the nucleus cuneiformis and the substantia nigra. The periaqueductal gray was found to have numerous intrinsic connections and contained a significant number of labeled cells both above and below the injection site in each case. Other structures containing significant label in the midbrain and isthmus region included the nucleus subcuneiformis, the ventral tegmental area, the locus coeruleus and the parabrachial nuclei. The medullary and pontine reticular reticular formation provide the largest input to the periaqueductal gray from the lower brain stem. The midline raphe magnus and superior central nucleus also supply a significant fiber projection to the central gray. Both the trigeminal complex and the spinal cord provide a minor input to this region of the midbrain. The sources of afferent projections to the periaqueductal gray are extensive and allow this midbrain region to be influenced by motor, sensory and limbic structures. In addition, evidence is provided which indicates that the four subdivisions of the central gray receive differential projections from the brain stem as well as from higher brain structures.

Afferent Pathways↗
PubMed1982

The sites of origin brain stem neurotensin and serotonin projections to the rodent nucleus raphe magnus.

The combined horseradish peroxidase retrograde transport-peroxidase-antiperoxidase immunohistochemical procedure was utilized in the present study to ascertain the sites of origin of serotonin and neurotensin projections to the rodent nucleus raphe magnus. The major serotonin inputs to the raphe magnus arise from the B-8 and B-9 groups of Dahlstrom and Fuxe (Dahlstrom, A., and K. Fuxe (1964) Acta Physiol. Scand. Suppl. 232 62: 1-55), the nucleus reticularis paragigantocellularis, and the nucleus reticularis gigantocellularis pars alpha. Neurotensinergic projections to the raphe magnus originate predominantly from the periaqueductal gray, the nucleus solitarius, the dorsal and ventral parabrachial nuclei, and the nucleus cuneiformis. The periaqueductal gray and the nucleus paragigantocellularis were found to provide both a neurotensin and a serotonin projection to this raphe nucleus. The present results indicate that several brain stem nuclei, which have been implicated previously in endogenous analgesia mechanisms, provide serotonergic and neurotensinergic input to the nucleus raphe magnus.

Afferent Pathways↗
PubMed1981

Specialized ependymal ridges in the cerebral aqueduct of the rat.

Novel paired ependymal ridges (EPRS) have been identified in the ventrolateral wall of the cerebral aqueduct of the rat. Scanning electron microscopic techniques revealed that the dorsolateral and ventromedial ridges differ from each other in surface morphology. Using the PAP immunohistochemical technique, the EPRS demonstrate a dense innervation of both serotonin and LH-RH fibers when compared to the surrounding midbrain periaqueductal gray and the "non-ridge" ependyma of the aqueduct. Each ridge is composed of a single layer of ependymal cells with a central core of subependymal cells and numerous blood vessels. Ependymal cells resembling tanycytes extend between the lumen of the aqueduct and the subependymal capillaries. It is suggested that the EPRS may serve as sites for the release of neurochemicals into the cerebrospinal fluid.

Animals↗
PubMed1981

Modes of protein and peptide uptake in the pineal gland of the Mongolian gerbil: an ultrastructural study.

The possible existence of either a blood-brain barrier or a CSF-brain barrier was examined in the pineal gland of the Mongolian gerbil using the ultrastructural tracers, horseradish peroxidase (HRP) and microperoxidase (MP). The mechanism of protein and peptide transport within the pineal gland and its possible relationship to pineal concretions was also considered. Gerbils were injected with either MP or HRP intravenously (IV), or they received intraventricular (IVT) injections of HRP. The IV injections resulted in both MP and HRP movement through the endothelial cells of the gland by vesicular transport and by diffusion through the endothelial cells of the gland by vesicular transport and by diffusion through the endothelial intercellular junctions. Following the IVT injections, the tracer was demonstrated in the subarachnoid space as well as in the glial cells associated with the periphery of the gland. In addition, after the IVT injections, rounded enlargements of the intercellular space that resembled canaliculi were filled with reaction product. In both cases (IVT and IV), the reaction product was localized to the perivascular space, to the glial cells and pinealocytes, and to the intercellular spaces. More importantly, there was specific localization of the tracers in the vacuolated pinealocytes and in the pineal concretions. The results of this study demonstrate several significant findings: 1) neither a blood-brain barrier nor a CSF-brain barrier exists in the pineal gland of the gerbil, 2) localization of the tracers in pineal concretions indicates a relationship between these structures and protein and peptide storage within the gland, and 3) the presence of the tracers within canaliculi after the IVT injections suggests a possible mode of secretion of pineal substances into the CSF.

Animals↗
PubMed1981

Brain functional activity during PAG stimulation-produced analgesia: a 2-DG study.

The autoradiographic 2-deoxyglucose method for regional cerebral metabolic activity was modified for use with tritium label to determine which brain stem and spinal cord nuclei changed their functional neural activity during periaqueductal gray stimulation-produced analgesia. The greatest changes in activity during electrical stimulation of the periaqueductal gray occurred in nucleus paragigantocellularis, the ventral portion of the nucleus reticularis gigantocellularis, and the nucleus cuneiformis. Substantial increases in metabolic activity were also evident in the spinal trigeminal nucleus and the substantia gelatinosa. Many of the regions which displayed increased functional activity in the present study have been shown to possess substantial enkephalin immunoreactivity. While several of these structures have previously been implicated in modulation of nociceptive transmission, this study raises the possibility that other brain stem nuclei may also participate in analgesic mechanisms.

Animals↗
PubMedDate not supplied

Possible origin of glutamatergic projections to the midbrain periaqueductal gray and deep layer of the superior colliculus of the rat.

The possible origin of glutamatergic input to the rodent periaqueductal gray (PAG) was analyzed utilizing a combined retrograde transport-immunocytochemical technique. Injections of wheat germ agglutinin-horseradish peroxidase were made into the PAG of 12 adult rats and into the deep layer of the superior colliculus in 2 rats. The brain tissue was first reacted histochemically to demonstrate the retrograde tracer and subsequently processed with immunohistochemical techniques using a recently developed monoclonal glutamate antibody. Following PAG injections, several brain areas were found to contain double-labeled neurons. The greatest number of double-labeled glutamate-like immunoreactive neurons were observed in the zona incerta, spinal trigeminal nucleus, cuneiform nucleus, cingulate cortex, cerebellar interpositus nucleus, deep mesencephalic nucleus and the PAG itself. Double-labeled neurons were also observed in several other nuclei including the pretectal nuclei, the frontal and occipital cortex, several reticular nuclei, the dorsomedial hypothalamic nucleus, and the substantia nigra. Many of the same nuclei contained double-labeled neurons following collicular injections, but in addition, double-stained cells were found in the primary visual cortex, lateral dorsal and lateral posterior thalamic nuclei, nucleus of the posterior commissure, ventral lateral geniculate nucleus, dorsal column nuclei and several additional pretectal nuclei. The results of this double-labeling study raise the possibility that these nuclei may provide glutamatergic inputs to the midbrain PAG and/or superior colliculus. These putative glutamatergic afferent projections may ultimately influence the PAG's role in several important functions including antinociception, defensive mechanisms or vocalization and may also play a role in the superior collicular involvement in defensive mechanisms, in visuo-motor integration in the orienting reflex and in facilitating shifts in gaze.

Animals↗