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Biomedical subjects

Peter C Brunjes

Publications and source records attributed to Peter C Brunjes.

6 recordsLinked to original sources
PubMed2006

Differences in chemo- and cytoarchitectural features within pars principalis of the rat anterior olfactory nucleus suggest functional specialization.

The anterior olfactory nucleus (AON) lies between the olfactory bulb and piriform cortex and is the first bilaterally innervated structure in the olfactory system. It is typically divided into two subregions: pars externa and pars principalis. We examined the cytoarchitecture of pars principalis, the largest cellular area of the region, to determine whether it is homogeneously organized. Quantitative Nissl studies indicated that large cells (cell body area >2 standard deviations (SD) larger than the mean cell size) are densest in lateral and dorsolateral regions, while small cells (>1 SD smaller than the mean) are more numerous in medial and ventral areas. Further evidence for regional differences in the organization of the AON were obtained with immunohistochemistry for calbindin (CALB), parvalbumin (PARV), glutamic acid decarboxylase (GAD), and choline transporter (CHT). Cells immunopositive for CALB (CALB+) were denser in the deep portion of Layer II, although homogeneously dispersed throughout the circumference of the AON. PARV+ cells were located in the superficial half of Layer II and were sparse in ventral and medial regions. CHT+ and GAD+ fibers were denser in lateral versus medial regions. No regional differences were found in GAD+ somata, or in norepinephrine transporter or serotonin transporter immunoreactivity. The observed regional differences in cyto- and chemoarchitectural features may reflect functional heterogeneity within the AON.

Animals↗
PubMed2005

A field guide to the anterior olfactory nucleus (cortex).

While portions of the mammalian olfactory system have been studied extensively, the anterior olfactory nucleus (AON) has been relatively ignored. Furthermore, the existing research is dispersed and obscured by many different nomenclatures and approaches. The present review collects and assembles the relatively sparse literature regarding the portion of the brain situated between the olfactory bulb and primary olfactory (piriform) cortex. Included is an overview of the area's organization, the functional, morphological and neurochemical characteristics of its cells and a comprehensive appraisal of its efferent and afferent fiber systems. Available evidence suggests the existence of subdivisions within the AON and demonstrates that the structure influences ongoing activity in many other olfactory areas. We conclude with a discussion of the AON's mysterious but complex role in olfactory information processing.

Animals↗
PubMed2004

Experience-dependent activation of extracellular signal-related kinase (ERK) in the olfactory bulb.

Protein kinase-mediated signaling cascades play a fundamental role in translating extracellular signals into cellular responses in CNS neurons. The mitogen-activated protein kinase / extracellular signal-regulated kinase (MAPK/ERK) pathway participates in regulating diverse neuronal processes such as proliferation, differentiation, survival, synaptic efficacy, and long-term potentiation by inducing cAMP-response element (CRE)-mediated gene transcription. Central olfactory structures show plasticity throughout the lifespan, but the role of the MAPK/ERK pathway in odor-evoked activity has yet to be determined. Therefore, we examined the effect of odorant exposure and early postnatal deprivation on ERK activity. We found that odor stimulation induced ERK phosphorylation, that activation of the ERK pathway was decreased with early postnatal deprivation, and that ERK phosphorylation was subsequently increased by restoring stimulation. Further, locations of ERK activation in bulbar neurons after exposure to single odorants corresponded to odor-evoked activity patterns found with other measures of activity in the bulb. Finally, due to the cytoplasmic location of pERK, activated dendrites belonging to the primary excitatory output neurons of the bulb were observed following a single odor exposure. The results indicate that the MAPK/ERK pathway is activated by odorant stimulation and may play an important role in developmental sensory plasticity in the olfactory bulb.

Animals↗
PubMed2004

Taste bud cell dynamics during normal and sodium-restricted development.

Taste bud volume increases over the postnatal period to match the number of neurons providing innervation. To clarify age-related changes in fungiform taste bud volume, the current study investigated developmental changes in taste bud cell number, proliferation rate, and life span. Taste bud growth can largely be accounted for by addition of cytokeratin-19-positive taste bud cells. Examination of taste bud cell kinetics with 3H-thymidine autoradiography revealed that cell life span and turnover periods were not altered during normal development but that cells were produced more rapidly in young rats, a prominent modification that could lead to increased taste bud size. By comparison, dietary sodium restriction instituted during pre- and postnatal development results in small taste buds at adulthood as a result of fewer cytokeratin-19-positive cells. The dietary manipulation also had profound influences on taste bud growth kinetics, including an increased latency for cells to enter the taste bud and longer life span and turnover periods. These studies provide fundamental, new information about taste bud development under normal conditions and after environmental manipulations that impact nerve/target matching.

Animals↗
PubMed2002

Comparative study of aging in the mouse olfactory bulb.

Gene knockout technologies have been used to elevate the mouse as a model species. However, little work has examined age and strain differences in the mouse olfactory system. The present study compared the olfactory bulbs of mature (6 month) and aged (24 month) males of BALB/cBy, C57BL/6J, and DBA/2 strains. Volumes of the glomerular (GLM), external plexiform (EPL), and mitral/granule cell (MIG) layers varied little from strain to strain. Volume measurements increased with age even when corrected for body weight differences. Two nonoverlapping interneuron populations were examined with immunohistochemistry. Staining for the calcium binding protein calretinin varied little between strains, but age-related increases in staining were seen in EPL of C57BL/6J mice. Typical patterns of tyrosine hydroxylase immunoreactivity were observed in all subjects except for old DBA/2 mice, which evidenced considerable staining in submitral areas. Age-related increases were observed in BALB/cBy and DBA/2 mice but not in the C57BL/6J strain. Glial fibrillary acidic protein staining was similar in old BALB/cBy and DBA/2 mice, with astrocytes in all layers of the bulb, but more concentrated in the MIG. However, C57BL/6J tissue revealed very large astrocytes relatively evenly distributed in all layers. Cell proliferation dropped dramatically with age. Labeled cells could still be observed along the lateral ventricles, but very few were observed within the rostral migratory stream or subventricular zone. Although TUNEL labeling revealed many apoptotic figures in the granule cell layer of young subjects, almost no staining was seen in aged mice.

Aging↗