Serotonin: a regulator of neuronal morphology and circuitry.

Serotonin is an important neuromodulator associated with a wide range of physiological effects in the central nervous system. The exact mechanisms whereby serotonin influences brain development are not well understood, although studies in invertebrate and vertebrate model organisms are beginning to unravel a regulatory role for serotonin in neuronal morphology and circuit formation. Recent data suggest a developmental window during which altered serotonin levels permanently influence neuronal circuitry, however, the temporal constraints and molecular mechanisms responsible are still under investigation.

Serotonergic dystrophy induced by excess serotonin.

Administration of certain serotonin-releasing amphetamine derivatives (fenfluramine and/or 3,4-methylenedioxymethamphetamine, MDMA, 'ecstasy') results in dystrophic serotonergic morphology in the mammalian brain. In addition to drug administration, dystrophic serotonergic neurites are also associated with neurodegenerative disorders. We demonstrate here that endogenously elevated serotonin in the Drosophila CNS induces aberrant enlarged varicosities, or spheroids, that are morphologically similar to dystrophic mammalian serotonergic fibers.

Drosophila serotonergic varicosities are not distributed in a regular manner.

Neurons of the brain form complex tree-like structures that are critical for function. Here we examine the spatial pattern of serotonergic varicosities, the synaptic sites of serotonin release in the central nervous system (CNS). These varicosities are thought to form largely nonjunctional-type connections that partition in a grid-like manner in order to distribute evenly the neuromodulatory neurotransmitter serotonin.

Branch architecture of the fly larval abdominal serotonergic neurons.

In the metazoan central nervous system (CNS), serotonergic neurons send projections throughout the synaptic neuropil. Little is known about the rules that govern these widespread neuromodulatory branching patterns. In this study, we utilize the Drosophila as a model to examine serotonergic branching.

A freeware java tool for spatial point analysis of neuronal structures.

Spatial point analysis is an analytical approach towards understanding patterns in the distribution of single points, such as synapses. To aid in this type of analysis of neuronal structures, a freeware tool, called PAJ, has been developed. This Java-based tool takes 3D Cartesian coordinates as input and performs a range of analyses to test for underlying patterns.

Developmental effects of SSRIs: lessons learned from animal studies.

Selective serotonin reuptake inhibitors (SSRIs) are utilized in the treatment of depression in pregnant and lactating women. SSRIs may be passed to the fetus through the placenta and the neonate through breastfeeding, potentially exposing them to SSRIs during peri- and postnatal development. However, the long-term effects of this SSRI exposure are still largely unknown.

A solid-phase immunostaining protocol for high-resolution imaging of delicate structures in the Drosophila larval central nervous system (CNS).

INTRODUCTIONThis protocol describes a method for mounting and immunostaining Drosophila larval tissue in preparation for high-resolution fluorescent imaging of fine structures in the central nervous system (CNS). Affixing the tissue directly to the coverslip and then moving the coverslip between wash solutions provides a simple solid-phase method of immunostaining that assists in preserving fine structures. This method also easily allows for manipulations and/or viewing of the live sample prior to fixation if desired.

A behavioral stress assay in Drosophila larvae.

INTRODUCTIONThis protocol describes a simple behavioral assay designed to test the response of Drosophila larvae to a homeostatic insult: bright light. Treating normally photophobic larvae with bright light before placing them near a target food source reveals a greater latency to reach the target when compared to controls not receiving light treatment. This effect is reversible given a recovery period after light treatment, and it may reveal a method by which to measure behavioral plasticity and stress responses in fruit fly larvae.

Development and sensitivity to serotonin of Drosophila serotonergic varicosities in the central nervous system.

Serotonin is a classical small-molecule neurotransmitter with known effects on developmental processes. Previous studies have shown a developmental role for serotonin in the fly peripheral nervous system. In this study, we show that serotonin can modulate the development of serotonergic varicosities within the fly central nervous system.

An assay of behavioral plasticity in Drosophila larvae.

Stress, or threats to homeostasis, is a universal part of life. Organisms face changing and challenging situations everyday, and the ability to respond to such stress is essential for survival. When subjected to acute stress, the body responds molecularly and behaviorally in order to recover a steady state.

Variation in serotonergic and dopaminergic neuronal survival in the central nervous system of adult Drosophila.

Loss of serotonergic and dopaminergic neurons may have serious implications for normal brain function. Drosophila models of neurodegenerative diseases utilize the short life-span and simple anatomy of the fly to characterize the molecular and genetic processes characteristic of each dysfunctional state. In fly embryonic and larval ventral nerve cords, serotonergic and dopaminergic neurons are positioned in a stereotypic pattern that is reorganized during metamorphosis.

robo2 and robo3 interact with eagle to regulate serotonergic neuron differentiation.

The function of the central nervous system (CNS) depends crucially upon the correct differentiation of neurons and formation of axonal connections. Some aspects of neuronal differentiation are known to occur as axonal connections are forming. Although serotonin is a highly conserved neurotransmitter that is important for many CNS functions, little is known about the process of serotonergic neuron differentiation.