<i>Retinal illumination produces synaptic inhibition of a neurosecretory organ in the crayfish</i>, pacifastacus leniusculus (<i>Dana</i>)

Kirk, Mark D.; Prugh, John I. P.; Glantz, Raymon M.

doi:10.1002/neu.480140608

Cited by 11 publications

(2 citation statements)

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“…These neurons closely resemble previously identified neurosecretory neurons that exhibit tonic activity in darkness and are inhibited under illumination. It has been argued that these neurons are involved in the feedback control of dark adaptation and/or circadian changes in visual sensitivity (154). Thus, RPCH appears to modulate DP and photoreceptors of the retina via two pathways, via the circulation from the XOSG and via specific interneurons.…”

Section: Red Pigment Concentrating Hormone (Rpch)mentioning

confidence: 99%

Circadian clocks in crustaceans: identified neuronal and cellular systems

Strauß

Dircksen²

2010

Front Biosci

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Circadian rhythms are known for locomotory and reproductive behaviours, and the functioning of sensory organs, nervous structures, metabolism and developmental processes. The mechanisms and cellular bases of control are mainly inferred from circadian phenomenologies, ablation experiments and pharmacological approaches. Cellular systems for regulation summarised here comprise the retina, the eyestalk neuroendocrine X-organ-sinus gland system, several neuropeptides such as red pigment concentrating, hyperglycaemic and pigment-dispersing hormones, and factors such as serotonin and melatonin. No master clock has been identified, but a model of distributed clockwork involves oscillators such as the retinular cells, neurosecretory systems in the optic lobes, putative brain pacemakers, and the caudal photoreceptor. Extraretinal brain photoreceptors mediate entrainment. Comparative analyses of clock neurons and proteins known from insects may allow the identification of candidate clock neurons in crustaceans as putative homologues in the two taxa. Evidence for the existence of "insect-like" intracellular clock proteins and (light sensitive) transcription factors is scarce, but clock-, period-, and cryptochrome-gene products have been localised in the CNS and other organs rendering further investigations into crustacean clockwork very promising.

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Section: Red Pigment Concentrating Hormone (Rpch)mentioning

confidence: 99%

Circadian clocks in crustaceans: identified neuronal and cellular systems

Strauß

Dircksen²

2010

Front Biosci

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“…Some neurons of this group have been shown to be immunopositive to an antibody against the Red Pigment Concentration Hormone (Preciado et al, 1994) and to receive inhibitory light input (Kirk et al, 1983). It will be interesting to investigate whether DA and RPCH localize in some neurons in this cluster.…”

Section: Discussionmentioning

confidence: 98%

Dopaminergic Modulation of Neurosecretory Cells in the Crayfish

Álvarez¹,

Villalobos²,

Rosete³

et al. 2005

Cell Mol Neurobiol

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The main aims of this paper are (a) to locate possible dopaminergic neurons in the eyestalk with anti-tyrosine hydroxylase antibodies, (b) to search for the presence of dopamine (DA) in the nervous structures of the eyestalk, (c) to explore its release, and (d) to test the effect of DA on neurosecretory cells in the eyestalk. Experiments were performed in adult crayfishes Procambarus clarkii, in isolated optic peduncle. Immunocytochemistry was made with the antibody against its precursor synthesizing enzyme tyrosine-hydroxylase. The content and release studies of DA were made using high performance liquid chromatography (HPLC). Extracellular and intracellular recordings were conducted with conventional recording techniques. A large number (approximately 2000) of immunopositive somata of different sizes and shapes were identified in various regions of the eyestalk. The majority of somata are of the smallest size (5-25 microm diameter). DA content in the eyestalk was 5.6 +/- 0.1 pmol per structure; the greatest content is in the MT (over 60%). A basal level release of DA was observed. Incubation of eyestalks in solution containing a high K+ concentration increased the DA release (79%). Two effects of DA on the excitability of X-organ neurons were observed; an excitatory effect on neurons of approximately 25 microm somata diameter and another inhibitory effect in the group of approximately 35-microm somata diameter neurons. The excitation occurs with a depolarization and decrement of membrane conductance in the cell soma while the inhibition occurs with a hyperpolarization and increment of membrane conductance in soma. We concluded the following: (1) Dopamine is present in each optic ganglia of the crayfish eyestalk. (2) There is a basal release of DA from the isolated eyestalk. (3) DA release is enhanced threefold by eyestalk incubation in 40 mM [K+] solution. (4) DA selectively excites a population of neurons with low-speed conduction axons, and small somata in the X-organ-sinus gland system, while inhibiting another population characterized by higher axonal conduction speed and large somata. (5) These observations support a role for DA as a neurotransmitter or neuromodulator in the X-organ neurons of the crayfish eyestalk.

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