Dynamics and plasticity of peptidergic control centres in the retino‐brain‐pituitary system of <i>Xenopus laevis</i>

Krämer, Bianca; Kolk, Sharon M.; Berghs, C.A.F.M.; Tuinhof, R.; Ubink, Ruud; Jenks, Bruce G.; Roubos, Eric W.

doi:10.1002/jemt.1132

Cited by 19 publications

(19 citation statements)

References 135 publications

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“…Not surprisingly, tectum ablation did not disrupt visual background adaptation, a light-evoked neuroendocrine reflex that affects pigment cells in the skin. In other species, this response is mediated by a hypothalamo-pituitary projection with direct retinal input (e.g., Kramer et al, 2001). …”

Section: Ten Visual Systems Of Zebrafishmentioning

confidence: 99%

Of lasers, mutants, and see‐through brains: Functional neuroanatomy in zebrafish

Gahtan

Baier

2004

J. Neurobiol.

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Behavioral functions are carried out by localized circuits in the brain. Although this modular principle is clearly established, the boundaries of modules, and sometimes even their existence, are still debated. Zebrafish might offer distinct advantages in localizing behaviors to discrete brain regions because of the ability to visualize, record from, and lesion precisely identified populations of neurons in the brain. In addition, genetic screens in zebrafish enable the isolation of mutations that disrupt neural pathways and/or behaviors, as an alternative lesioning technique with complementary strengths to laser ablations. For example, the Mauthner cell, a large identified neuron in the hindbrain, has been postulated to be both necessary and sufficient for the execution of escapes. We discuss in this review how experiments, using laser ablations, calcium imaging, and mutants have eroded this notion. Even in a simple behavior, such as escape, many parallel pathways appear to be involved with no single one being absolutely necessary. Lesion studies and the analysis of behavioral mutants are now also beginning to elucidate the functional architecture of the zebrafish visual system. Although still in an embryonic stage, the neuroanatomy of behaviors in zebrafish has a bright future.

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Section: Ten Visual Systems Of Zebrafishmentioning

confidence: 99%

Of lasers, mutants, and see‐through brains: Functional neuroanatomy in zebrafish

Gahtan

Baier

2004

J. Neurobiol.

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“…To identify the contribution of DA neurons to regulation of pigmentation we exposed stage 42 larvae for 30 min to 10 nM sulpiride, a dopamine D 2 receptor antagonist, because coexpressed GABA and NPY can contribute to regulation of this behavior12,14. Sulpiride treatment blocks changes in skin pigmentation in response to altered illumination (Fig.…”

Section: Dopaminergic Neurons Regulate Pigmentationmentioning

confidence: 99%

Illumination controls differentiation of dopamine neurons regulating behaviour

Dulcis¹,

Spitzer²

2008

Nature

114

165

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Specification of the appropriate neurotransmitter is a crucial step in neuronal differentiation because it enables signaling among populations of neurons. Experimental manipulations demonstrate that both autonomous and activity-dependent genetic programs contribute to this process during development, but whether natural environmental stimuli specify transmitter expression in a neuronal population is unknown. We investigated neurons of the ventral suprachiasmatic nucleus that regulate neuroendocrine pituitary function in response to light in teleosts, amphibia and in primates. We find that altering light exposure, which changes the sensory input to the circuit controlling adaptation of skin pigmentation to background, changes the number of neurons expressing dopamine in amphibian larvae in a circuit-specific and activity-dependent manner. Newly dopaminergic neurons then regulate changes in camouflage coloration in response to illumination. Thus physiological activity alters the numbers of behaviorally relevant aminergic neurons in the brain at postembryonic stages of development. The results may be pertinent to changes in cognitive states that are regulated by biogenic amines.Keywords dopaminergic neurons; neurotransmitter respecification; sensory stimulation; activity-dependent plasticity; ventral suprachiasmatic nucleus; retinohypothalamic projection; background adaptation Electrical activity plays a key role in neurotransmitter specification [1][2][3][4] and postsynaptic receptor expression 5-7 in differentiating neurons. Moreover, postsynaptic receptors can be selected to match the transmitters expressed presynaptically8 , 9. L-type calcium channels have been implicated in the developmental expression of dopamine, because a loss-of-function mutation in tottering mutant mice 10 leads to abnormal expression of tyrosine hydroxylase (TH), the rate-limiting dopamine-synthetic enzyme 11 . TH is ectopically co-expressed with GABA in cerebellar Purkinje neurons in these mutants. These studies led us to hypothesize that activity driven by environmental stimuli will cause neurons to express an additional transmitter, without changing the number of neurons or affecting their original transmitter phenotype. The neurons would be able to perform a new function in addition to their default role. Hijacking activity-dependent mechanisms regulating transmitter expression could be a useful step toward the development of clinical treatments that drive transmitter specification in selected classes of neurons.Here we have examined the role of illumination in the specification of dopamine in neurons of the ventral suprachiasmatic nucleus (VSC) of Xenopus laevis. This is an attractive system to investigate during both pre-and post-embryonic development because of the small number of dopaminergic (DA) neurons, the clearly described retinohypothalamic circuitry to which they belong, and their well characterized inhibition of melanotrope cells that control skin pigmentation 12, 13. The neuroanatomy and behavior of the backgroun...

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“…The mutant GR can bind cortisol and translocate to the nucleus, but shows no transcriptional activity (Ziv et al, 2012). The mutant was identified on the basis of impaired visual background adaptation (VBA; Muto et al, 2005), a GR-dependent neuroendocrine response that causes skin pigment cells to contract under bright illumination (Kramer et al, 2001). gr s357 larvae appear darker than gr wt in the VBA assay (Figure 2) showed reduced swimming activity (Muto et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

A zebrafish model of glucocorticoid resistance shows serotonergic modulation of the stress response

Griffiths¹,

Schoonheim²,

Ziv³

et al. 2012

Front. Behav. Neurosci.

132

128

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One function of glucocorticoids is to restore homeostasis after an acute stress response by providing negative feedback to stress circuits in the brain. Loss of this negative feedback leads to elevated physiological stress and may contribute to depression, anxiety, and post-traumatic stress disorder. We investigated the early, developmental effects of glucocorticoid signaling deficits on stress physiology and related behaviors using a mutant zebrafish, grs357, with non-functional glucocorticoid receptors (GRs). These mutants are morphologically inconspicuous and adult-viable. A previous study of adult grs357 mutants showed loss of glucocorticoid-mediated negative feedback and elevated physiological and behavioral stress markers. Already at 5 days post-fertilization, mutant larvae had elevated whole body cortisol, increased expression of pro-opiomelanocortin (POMC), the precursor of adrenocorticotropic hormone (ACTH), and failed to show normal suppression of stress markers after dexamethasone treatment. Mutant larvae had larger auditory-evoked startle responses compared to wildtype sibling controls (grwt), despite having lower spontaneous activity levels. Fluoxetine (Prozac) treatment in mutants decreased startle responding and increased spontaneous activity, making them behaviorally similar to wildtype. This result mirrors known effects of selective serotonin reuptake inhibitors (SSRIs) in modifying glucocorticoid signaling and alleviating stress disorders in human patients. Our results suggest that larval grs357 zebrafish can be used to study behavioral, physiological, and molecular aspects of stress disorders. Most importantly, interactions between glucocorticoid and serotonin signaling appear to be highly conserved among vertebrates, suggesting deep homologies at the neural circuit level and opening up new avenues for research into psychiatric conditions.

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Dynamics and plasticity of peptidergic control centres in the retino‐brain‐pituitary system of Xenopus laevis

Cited by 19 publications

References 135 publications

Of lasers, mutants, and see‐through brains: Functional neuroanatomy in zebrafish

Of lasers, mutants, and see‐through brains: Functional neuroanatomy in zebrafish

Illumination controls differentiation of dopamine neurons regulating behaviour

A zebrafish model of glucocorticoid resistance shows serotonergic modulation of the stress response

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