Biomedical subjects

I Hähnlein

Publications and source records attributed to I Hähnlein.

5 recordsLinked to original sources

PubMed1996

Datura stramonium lectin staining of glial associated extracellular material in insect brains.

To investigate how glial cells structure the neuropile of olfactory pathways in the brains of honeybees and locusts, we used a lectin as a carbohydrate specific molecular label. On frozen sections, Datura stramonium lectin (DSL) stained extracellular material which is mainly associated with glial cells. Preadsorption of the DSL with the carbohydrate N, N'-diacetylchitobiose blocked the staining. The location of glial cells was detected by an antiserum against the glial-specific nuclear repo-protein. Lectin-staining surrounded the neuropile of the antennal lobe, axonal projections of olfactory relay neurons, and the mushroom body neuropile. Within the mushroom body neuropile of the bee, DSL-staining was especially intense at the branching sites of the Kenyon cell axons and in the ventral part of the alpha-lobe. The dissection of the various cellular contributions to the lectin-staining in dissociated cell cultures suggested that certain glial cells, but also neuronal somata of the antennal lobe and Kenyon cells of the mushroom bodies express the label. The expression of lectin-staining matures during the pupal development of the bee, whereas in larval stages of the hemimetabolous locust, the staining pattern appears already completed. Since carbohydrate recognition is thought to play an important role in the formation of neuronal networks, the glial derived extracellular material may contribute to the morphogenesis and structural integrity of the olfactory neuropiles.

Animals↗

PubMed1996

Morphology of neuroglia in the antennal lobes and mushroom bodies of the brain of the honeybee.

We investigated the distribution and anatomical organization of glial cells in the antennal lobes and mushroom bodies of the honeybee. Reconstructions from serial sections, prepared according to the ethyl gallate method, revealed the entire morphology of glial cells in neuropiles, tracts, and the soma rind. The distribution of the glial cell bodies in the neuropiles was derived from the staining of cell nuclei with a fluorescent dye. There are glial cells of different shape in the soma rind which are wrapped around the neuronal cell bodies of the antennal lobes and the Kenyon cells of the mushroom bodies. Glial cells surround neuropilar areas such as the external and lateral sides of the glomeruli of the antennal lobes. Whereas we could not detect glia in the glomerular neuropile, glial cells with long processes are located in the core of the antennal lobe. Extensions of these glial cells also invade tracts containing the olfactory projection neurons. A layer of glial cells separates the mushroom body neuropile from the surrounding protocerebral neuropile. The neuropile of the mushroom bodies is clearly compartmented by glial cells. There is a high density of astrocyte-like glia in a column of the pedunculus which can be followed to the ventral part of the alpha-lobe. A network of mushroom body intrinsic glial cells separates the alpha-lobe from the beta-lobe and the pedunculus. This anatomical description of glial cell types in olfactory information processing pathways of an insect brain provides a framework for further physiological studies of neuroglia in dissociated cell culture.

Animals↗

PubMed1995

NADPH-diaphorase expression in neurones and glial cells of the locust brain.

Using NADPH-diaphorase (NADPH-d) staining as a marker for the enzyme nitric oxide synthase (NOS) we investigated the possible sites of nitric oxide (NO) synthesis in the olfactory pathways of an insect brain. Staining of frozen sections revealed NADPH-d activity in neurones and in glial cells. A cluster of intensely stained interneurones innervates the neuropile of the antennal lobe. NADPH-d expression in the mushroom bodies showed a compartmentalized pattern. The mushroom body intrinsic Kenyon cells did not express NADPH-d. The pedunculus and lobes showed fine granular staining and were invaded by NADPH-d-positive mushroom body extrinsic fibres. The expression of NADPH-d in glial cells enclosing the mushroom bodies suggest that insect glial cells may release NO as a messenger molecule.

Amino Acid Oxidoreductases↗

PubMed1994

Long-term habituation of an appetitive reflex in the honeybee.

We examined habituation of an appetitive component of the honeybee's feeding behaviour, the proboscis extension reflex. This reflex is elicited by touching one antenna with a droplet of sugar water. The response decrement was quantified by determining the number of trials necessary to abolish any visible response. Measurements of the time dependent spontaneous recovery demonstrated that habituation persists for at least 10 min, representing a simple form of short-term memory. When repeated training sessions were applied over 2 days, a long-term memory for habituation to appetitive sensory stimuli, lasting for 24 h was established.

Animals↗

PubMed1994

Decrease of gap junction number in the rat neural tube between ED 11 and ED 15.

The apical regions of neuroepithelial cells of 11 and 15 day-old rat embryos were found to be interconnected near their luminal surface by extended junctional complexes, consisting of tight junctions and desmosome-like contacts. On the 11th and 12th embryonal day, small gap junction cell contacts occur in the juxtaluminal region of the neural tube. Besides these intercellular gap junctions, annulated gap junctions, located intracellularly, were also detected at this developmental stage. The latter type is thought to originate from intercellular gap junctions by an invagination process in the course of degradation of extended contacts which exist between neuroepithelial cells in earlier developmental phases. The decrease of gap junction number by the 14th and 15th embryonal day could be correlated with processes of cellular development and differentiation.

Animals↗