Extracellular matrix glycoproteins inhibit neurite outgrowth of different types of identified leech neurons in culture

NeuronGrowth, a software for automatic quantification of neurite and filopodial dynamics from time-lapse sequences of digital images

We developed NeuronGrowth, a software for the automatic quantification of extension and retraction of neurites and filopodia, from time-lapse sequences of two-dimensional digital micrographs. NeuronGrowth requires a semiautomatic characterization of individual neurites in a reference frame, which is then used for automatic tracking and measurement of every neurite over the whole image sequence. Modules for sequence alignment, background subtraction, flat field correction, light normalization, and cropping have been integrated to improve the quality of the analysis. Moreover, NeuronGrowth incorporates a deconvolution filter that corrects the shadow-cast effect of differential interference contrast (DIC) images. NeuronGrowth was tested by analyzing the formation of outgrowth patterns by individual leech neurons cultured under two different conditions. Phase contrast images were obtained from neurons plated on CNS homogenates and DIC images were obtained from similar neurons plated on ganglion capsules as substrates. Filopodia were measured from fluorescent growth-cones of chick dorsal root ganglion cells. Quantitative data of neurite extension and retraction obtained by three different users applying NeuronGrowth and two other manually operated software packages were similar. However, NeuronGrowth required less user participation and had a better time performance when compared with the other software packages. NeuronGrowth may be used in general to quantify the dynamics of tubular structures such as blood vessels. NeuronGrowth is a free plug-in for the free software ImageJ and can be downloaded along with a user manual, a troubleshooting section and other information required for its use from http://www.ifc.unam.mx or http://www.ifc.unam.mx/ffm/index.html.

A method for semiautomatic tracing and morphological measuring of neurite outgrowth from DIC sequences

We present a method for semi-automatic tracing and measuring of neurite outgrowth from time-lapse sequences of digital Nomarski micrographs. The algorithm is based on neurite ridge extraction and characterization from a single frame, followed by an automatic neurite tracking and measurement along the image sequence. Our method was tested with two sequences one containing 29 and other with 77 frames taken at intervals of 2 min. Our method rendered comparable length measurements but better time performance than measurements made by use of certain public software.

Primary culture of the isolated terminal nerve-gonadotrophin-releasing hormone neurones derived from adult teleost (dwarf gourami, Colisa lalia) brain for the study of peptide release mechanisms

Terminal nerve (TN)-gonadotrophin-releasing hormone (GnRH) neurones are suggested to release GnRH peptides from widely-branched neural processes and the somatodendritic regions, depending on their firing activities. The released GnRH may exert its neuromodulatory actions on GnRH receptors located on various target neurones. The electrophysiological and morphological characteristics of TN-GnRH neurones, which are shared with other peptidergic neurones of vertebrate brains, are thought to represent general features of neuromodulatory and ⁄ or neurosecretory neurones. To address questions concerning the ways in which the electrical activities of peptidergic (TN-GnRH) neuronal somata affect GnRH release from different neuronal compartments, we established a primary culture system of TN-GnRH neurones, which will facilitate simultaneous recordings of various physiological signals from different compartments of a single TN-GnRH neurone cultured in a flat plane. The whole brain of an adult freshwater teleost, the dwarf gourami, was dissected out. The TN-GnRH neurones were then isolated and plated on a coverslip in culture medium. The isolated TN-GnRH neurones could be cultured for up to 2 weeks. In culture, the neurones grew both axon- and dendrite-like neurites, and these processes were phenotypically similar to those found in situ. Unlike the neurones in situ, the cultured neurones had somewhat depolarised resting membrane potentials and showed no spontaneous discharge, which, however, should not be considered to comprise unhealthy culture conditions. Instead, they showed subthreshold spontaneous membrane potential oscillations and could be induced to fire in phasic or tonic patterns. In addition, stimulus-induced exocytotic events could be demonstrated in the soma and neurites using a fluorescent dye, FM1-43. Thus, the present isolated culture of TN-GnRH neurones will open up a wide range of possibilities for studying cellular mechanism of exocytosis, generation of spontaneous firing activity, and neurite outgrowth in peptidergic neurones.