PubMed Health⌕ Search

Biomedical subjects

J A Olschowka

Publications and source records attributed to J A Olschowka.

At least 19 recordsLinked to original sources
PubMed1992

Rhythmic expression of Fos-related proteins within the rat suprachiasmatic nucleus during constant retinal illumination.

Within the retinorecipient or ventrolateral subfield of suprachiasmatic nuclei (SCN) in rodents, expression of the protein product of the c-fos proto-oncogene, Fos, is regulated by light. In the present study, the expression of Fos and Fos-related proteins within the SCN was examined immunocytochemically for evidence of rhythmic variation in rats sacrificed at different circadian times during exposure to constant retinal illumination (LL). In all animals, nuclear Fos immunoreactivity was mainly confined to an area of the SCN that was coextensive with neuropeptide Y-immunopositive fibers distinguishing the ventrolateral subfield of the nucleus. Moreover, Fos-immunostaining within the ventrolateral SCN of rats exposed to LL fluctuated over the course of the circadian cycle, such that the density of immunopositive cells within this subfield was 2 times greater during the subjective night than during the subjective day. Since Fos expression within the SCN oscillates in the absence of photoperiodic time cues and since the peak of this oscillation coincides with the circadian times when light modulates the periodicity of the SCN pacemaker, these data provide further evidence that expression of the c-fos gene may be a molecular signal in the circadian timekeeping mechanism in the SCN and its regulation by photic stimuli.

Animals↗
PubMed1992

Interaction of opioid peptide-containing terminals with dopaminergic perikarya in the rat hypothalamus.

Both direct pituitary and indirect CNS mechanisms have been postulated for the influence of opiate agonists on prolactin secretion. By examining the interactions between terminals of neurons containing opioid peptides and hypothalamic TH-positive cell bodies, this paper addressed the anatomical basis for the latter mechanism. Initial electron microscopic studies directly demonstrated contact between opioid peptide terminals and dopaminergic cell bodies and provided some visual criteria for assessing opioid-dopamine interactions at the light microscopic level. Using these guidelines, we examined the rates of contact on both A12 and A14 neurons of each of the three opioid peptide families: pro-enkephalin, pro-dynorphin, and pro-opiomelanocortin (POMC). For A14 neurons, many of which project to the posterior pituitary, contact rates were estimated at 15, 20, and 5% for dynorphin, Met-enkephalin, and ACTH (a POMC derivative), respectively. In contrast, the A12 dopamine neurons, which regulate prolactin secretion by inhibition, showed a roughly 70% contact rate with dynorphin axons (P less than 0.001) with Met-enkephalin and ACTH contact rates remaining low at 20 and 5% respectively. Contact frequency varied significantly during the estrus cycle only with dynorphin contacts on A12 neurons. Proestrus and diestrus (less so) showed a small but significant (P less than 0.05) elevation in contact rates versus estrus, male, lactating and pregnant groups. No other significant difference emerged among these groups. On the basis of these observations, we conclude that dynorphin represents a significant and specific factor in the innervation of A12 dopamine neurons. This relationship may account for some if not most of the influence of opiate agonists and antagonists on prolactin secretion.

Animals↗
PubMed1991

Induction of interleukin-1 beta mRNA in adult rat brain.

The ability of the central nervous system to produce the cytokine interleukin-1 beta (IL-1 beta) in response to challenge by activators of the mononuclear phagocyte system has been examined in vivo. Unilateral injection of a mixture of gamma-interferon (IFN-gamma) and lipopolysaccharide (LPS) into the forebrain of adult rats induced expression of IL-1 beta mRNA. In situ hybridization of IL-1 beta mRNA showed a gradient of cellular hybridization, which was most intense at the site of IFN-gamma/LPS injection. The reverse transcription--polymerase chain reaction (RT-PCR) was used to demonstrate the presence of IL-1 beta mRNA in normal rat brain, and to confirm increases in IL-1 beta mRNA levels following IFN-gamma/LPS injection. These studies show that IL-1 beta can be induced to high levels within the CNS as a consequence of exposure to potent stimulators of macrophage activation.

Animals↗
PubMed1991

Neuropeptide-Y innervation of the rat spleen: another potential immunomodulatory neuropeptide.

Neuropeptide-Y (NPY) is a 36 amino acid peptide that acts as a chemical messenger in the central and peripheral nervous systems. NPY often is found colocalized with the classical neurotransmitter norepinephrine (NE) and can potentiate the effects of this neurotransmitter postsynaptically in many systems. Using immunocytochemistry for NPY and specific lymphoid cell markers, we mapped the distribution of NPY-positive nerve fibers in the rat spleen. NPY-positive nerve fibers were present along the vasculature, trabeculae, and capsule, and also were found associated with specific lymphoid parenchymal compartments of the spleen, in close contact with lymphocytes and macrophages. These contacts were investigated further at the electron microscopic level. NPY-positive nerve terminals were found in close apposition with lymphocytes in the periarteriolar lymphatic sheath, and with lymphocytes and macrophages in the marginal zone. Previous studies have reported that postganglionic noradrenergic nerve fibers innervate specific lymphoid compartments of the rat spleen, with nerve terminals forming direct appositions with cells of the immune system. The possible colocalization of NPY and NE in these nerve fibers was investigated by chemical sympathectomy with 6-hydroxydopamine, followed by immunocytochemical labeling of NPY and tyrosine hydroxylase (TH), the rate-limiting enzyme in norepinephrine synthesis. Colocalization also was investigated by labeling for NPY with a fluorescent label, eluting the NPY, and staining for TH with diaminobenzidine as the label. These studies demonstrate that norepinephrine and NPY are colocalized in the postganglionic sympathetic nerve fibers of the rat spleen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Limited recovery of striatal dopaminergic fibers by adrenal medullary grafts in MPTP-treated aging mice.

Systemic injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) damages the dopaminergic (DA) nigrostriatal system in C57BL/6 mice. We have investigated the effect of MPTP neurotoxicity and subsequent adrenal medullary grafts into the striatum of young (2-3 months) and aging (12 months) mice. MPTP treatment (4 X 20 mg/kg ip given 3 or 12 h apart in young mice and 12 h apart in aging mice) resulted in 80-90% depletion of striatal DA and virtual disappearance of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers in both young and aging mice 1 week following treatment. Only partial recovery of TH-IR fibers was seen 5 weeks after MPTP treatment in young mice, while virtually no recovery was seen in aging mice. Adrenal medullary minced pieces were grafted into the striatum of young and aging mice 1 week after MPTP treatment. In young mice, dense TH-IR fibers were observed in the striatum on the grafted side 4 weeks later, far denser than those in sham-operated striatum. Although this staining was most prominent around the grafts, many TH-IR fibers also were found in the ventral striatum close to the nucleus accumbens. No such increase in TH-IR fibers was found on the nongrafted side. DA concentration on the grafted side recovered to 45% of the control level. In aging mice receiving similar grafts, TH-IR fibers also were observed in the grafted striatum, but were less dense and more restricted around the site of the graft compared with young mice. DA concentration on the grafted side was 29% of the control level. We conclude that the MPTP-depleted nigrostriatal DA system in aging mouse brain can recover partially following adrenal medullary grafts, but the degree of recovery is more limited compared with that in young brain.

Adrenal Medulla↗
PubMed1990

Photic regulation of c-fos expression in neural components governing the entrainment of circadian rhythms.

The rapid and transient induction of the proto-oncogene c-fos in mature neurons within the brain occurs in response to a variety of extracellular stimuli. To determine whether lighting conditions influence c-fos gene expression in the primary neural structures mediating the photoentrainment and generation of mammalian circadian rhythms, the expression of the c-fos protein (Fos) and related proteins in the retina and suprachiasmatic nuclei (SCN) of the anterior hypothalamus was examined immunohistochemically in rats exposed to a light-dark cycle of 12 h of light and 12 h of darkness (LD 12:12), constant light (LL), or constant dark (DD). The retina exhibited clear light-dark differences in the expression of Fos protein(s), such that immunopositive nuclei were readily evident during exposure to light (i.e., during the day of diurnal lighting or in LL), but were absent during exposure to darkness. In the SCN, the distribution of Fos immunoreactivity within specific subfields was differentially affected by photic conditions. Following exposure to light, a dense population of Fos-immunopositive cells was found in close association with the immunohistochemically distinct cell and fiber populations distinguishing the ventrolateral subfield of the SCN. In dark-exposed animals, Fos-immuno-reactive profiles were distributed throughout the SCN in areas coextensive with the immunohistochemical localization of peptidergic neural elements in both the ventrolateral and dorsomedial subfields. As a consequence of this light-dark difference in the distribution of Fos immunoreactivity, the density of labeled cells was increased within the ventrolateral SCN, but was decreased within the dorsomedial subfield, as a result of exposure to light versus darkness.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

A system of corticotropin releasing factor-containing amacrine cells in the rat retina.

Immunohistochemical processing of Long-Evans retina wholemounts using an antiserum directed against rat, human corticotropin releasing factor revealed a group of immunoreactive amacrine cells. Two subpopulations could be distinguished based primarily on the location of their cell bodies. One subpopulation had cell bodies situated along the junction of the inner nuclear layer and the inner plexiform layer. The other subpopulation had cell bodies in the ganglion cell layer. The latter was judged to be displaced amacrine cells since double-label experiments indicated that the pattern of corticotropin releasing factor-like immunoreactive staining in the ganglion cell layer did not coincide with that of ganglion cells labeled retrogradely with fluorogold. Corticotropin releasing factor-like immunoreactive amacrine cells on either side of the inner plexiform layer emitted processes which ramified extensively in sublamina 5 and, to a lesser degree, in sublamina 4. A minority of these cells also sent a single process to ramify in sublamina 1. Throughout the retina, corticotropin releasing factor-like immunoreactive cells were distributed relatively evenly, with a tendency to peak in the superior temporal region. Despite the anatomical classification into two subpopulations, it is proposed that the corticotropin releasing factor-like immunoreactive cells are functionally one system, influencing preferentially synaptic interactions associated with the inner half of the inner plexiform layer. The results of this study provide anatomical basis for further investigations of corticotropin releasing factor as a putative peptidergic neurotransmitter in the retina.

Animals↗
PubMed1987

Reinnervation of transplanted hypothalamic neurons by host aminergic fibers in rats.

Fetal mediobasal hypothalamic tissue which receives an extensive noradrenergic innervation in the adult brain, was implanted into the vicinity of the medial forebrain bundle of adult rats to determine whether host noradrenergic fibers would innervate the ectopically placed tissue in an organotypic manner. Tissue from the site of implantation was prepared for light and ultrastructural immunocytochemistry at 6, 12, or 20 weeks postsurgery. Putative host catecholamine fibers formed dense plexuses in localized portions of the grafts and made synaptic contacts with dendrites and somata of transplanted neurons. This suggests that a mature host central nervous system is capable of a region-specific integration of transplanted neurons.

Animals↗
PubMed1985

Noradrenergic and peptidergic innervation of lymphoid tissue.

Sympathetic noradrenergic nerve fibers innervate both the vasculature and parenchymal fields of lymphocytes and associated cells in several lymphoid organs, including the thymus, spleen, lymph nodes, gut-associated lymphoid tissue (GALT), and bone marrow, in a variety of mammalian species. This innervation is both regional and specific, and generally is directed into zones of T lymphocytes and plasma cells rather than into nodular regions or B lymphocyte regions. In the thymus, noradrenergic fibers enter with nerve bundles and plexuses around blood vessels, travel into the cortex from subcapsular plexuses and with the vasculature, and branch into the parenchyma of the thymic cortex. The vasculature and parenchymal regions of both the outer and deep cortex are innervated by these fibers. In the spleen, noradrenergic fibers enter with the vasculature, travel along the trabeculae and along the branching vasculature, and are distributed mainly in the white pulp along the central artery and associated periarterial lymphatic sheath. Fibers branch from a dense plexus around the central artery and travel into the parenchyma, where they end among fields of lymphocytes and other cell types. In lymph nodes, noradrenergic fibers enter at the hilus, travel along the vasculature and in a subcapsular plexus, and branch into the parenchyma in paracortical and cortical regions, where they end among lymphocytes. In the GALT, represented in these studies by rabbit appendix, sacculus rotundus, and Peyer's patches, noradrenergic fibers enter at the serosal surface, travel longitudinally with the muscularis interna, turn radially into internodular plexuses, plunge directly through the thymus-dependent zones, and ramify profusely among lymphocytes, enterochromaffin cells, and plasma cells in the interdomal regions. In the bone marrow, noradrenergic fibers enter with blood vessels, distribute deeply into the marrow on those vessels, and branch sparsely into the substance of the marrow. Immunocytochemical observations revealed the presence of neuro-peptide-like immunoreactivity in the thymus and spleen. Vasoactive intestinal peptide (VIP)-like immunoreactivity is found in varicose profiles in the thymus within the cortex. In the spleen, immunoreactive profiles showing neuropeptide Y-like, Met-enkephalin-like, cholecystokinin-8 (CCK)-like, and neurotensin-like immunoreactivity are present along the central artery of the white pulp and its smaller branches, with only sparse fibers of most of these peptides entering the parenchyma. CCK-like profiles are present in abundance in the white pulp among parenchymal elements.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic Fibers↗
PubMed1984

The subnuclear distribution of substance P, cholecystokinin, vasoactive intestinal peptide, somatostatin, leu-enkephalin, dopamine-beta-hydroxylase, and serotonin in the rat interpeduncular nucleus.

The distribution of immunofluorescent somata and processes within the interpeduncular nucleus (IPN) containing substance P (SP), cholecystokinin (CCK), vasoactive intestinal peptide (VIP), somatostatin (SST), leu-enkephalin (L-ENK), dopamine beta hydroxylase (DBH), and serotonin (5HT) was examined in male rats treated with colchicine 48 hours prior to perfusion. Serial sections were examined for immunofluorescence and variations in the density of fluorescence rated 1 + (sparse) to 4 + (dense). The rostral subnucleus contained SP, SST, and L-ENK-positive somata and processes. Substance P and VIP processes were present throughout the rostral subnucleus but were concentrated in two ovoid areas located dorsally in the caudal region of this subnucleus. Cholecystokinin and L-ENK processes surrounded these ovoid areas. The entire width of the central subnucleus was crossed by SP and L-ENK processes oriented horizontally in narrow bands. Substance P processes were also aligned into vertical columns adjacent to the lateral margins of the central subnucleus. Leu-enkephalin and 5HT processes were distributed throughout this subnucleus, while VIP processes were present only caudally. Dopamine beta hydroxylase processes were evenly distributed but were restricted from the vertical columns laterally. The intermediate subnuclei contained a sparse density of SP and 5HT processes that were present in proximity to the major blood vessels penetrating this subnucleus. Only DBH processes were evenly distributed. The lateral subnuclei contained a dense concentration of SP processes. The medial edges of this subnucleus were distinguished by VIP, CCK, L-ENK, and 5HT processes. The dorsal subnucleus contained 5HT, L-ENK, and SST-positive somata and processes. Substance P, VIP, CCK, and DBH processes were also present. Dorsal-lateral subnuclei contained SP, SST, L-ENK, and DBH processes. Interstitial subnuclei contained SP, CCK, L-ENK, 5HT, and DBH processes. This study demonstrates that perikarya and processes containing peptides and monoamines are distributed within subnuclei of IPN in a topographic and heterogeneous pattern. New features of IPN organization are revealed.

Animals↗
PubMed1983

Vasoactive intestinal polypeptide immunoreactive and cholinergic nerves in the whole mount preparation of the major cerebral arteries of the rat.

An immunofluorescence histochemical study of vasoactive intestinal polypeptide (VIP) was made in the major rat cerebral arteries of the whole mount preparation. A comparison was made between the distribution of VIP-immunoreactive and cholinergic nerves. An abundant number of VIP-containing nerves were observed in the internal carotid, anterior cerebral, middle cerebral and basilar artery. VIP and cholinergic nerves were unaffected by bilateral superior cervical ganglionectomy. The density and distribution of VIP-immunoreactive fibers was essentially the same as that of the cholinergic fibers of the rat cerebral vasculature. It is suggested that, as was previously demonstrated in other peripheral organs, VIP coexists within cholinergic neurons of the rat cerebral arteries.

Animals↗
PubMed1983

Bovine pancreatic polypeptide-like immunoreactive nerves in the rat major cerebral arteries.

Immunofluorescence histochemical observation of the major cerebral arteries of the rat demonstrated the presence of an extensive plexus of bovine pancreatic polypeptide (BPP) containing nerves. The density of the nerves were similar to those previously observed in the adrenergic plexus. The density of BPP-immunoreactive fibers markedly decreased following bilateral superior cervical ganglionectomy. It is concluded that BPP-containing fibers of the cerebral arteries emanate mostly from the superior cervical ganglion and that BPP and norepinephrine coexist in the adrenergic nerves.

Animals↗
PubMed1983

Vasoactive intestinal peptide inhibitory innervation in bovine mesenteric lymphatics. A histochemical and pharmacological study.

The localization of vasoactive intestinal peptide-immunoreactive nerves innervating bovine lymphatic vessels was studied by an immunohistochemical technique. Nerve fibers containing vasoactive intestinal peptide immunoreactivity were present in the smooth muscle layers as well as in the adventitia of all mesenteric lymphatics that were examined. The effect of vasoactive intestinal peptide on isolated lymphatic vessels in vitro was studied. Vasoactive intestinal peptide caused a concentration-dependent relaxation of bradykinin-induced contractions of lymphatic vessels. The threshold and maximum relaxations were achieved with vasoactive intestinal peptide at concentrations less than 6 X 10(-9) M and 3 X 10(-7) M, respectively. The relaxant response to vasoactive intestinal peptide was not modified by atropine, propranolol, bretylium, or tetrodotoxin. These results suggest that vasoactive intestinal peptide may be a possible inhibitory neurotransmitter that causes relaxation of lymphatic vessels.

Animals↗