Ipsilateral alterations in tryptophan hydroxylase activity in rat brain after hypothalamic 5,7-di-hydroxytryptamine lesion

Ljubic‐Thibal, Vesna; Dikšić, Mirko; Hamel, Edith; Raison, Sylvie; Pujol, Jean‐François; Weissmann, Dinah

doi:10.1016/0006-8993(96)00327-7

Cited by 7 publications

(6 citation statements)

References 29 publications

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“…Zhou et al (1998) reported that the OBX-associated axotomy of 5-HT fibers projecting into the olfactory bulb caused collateral sprouting and the regeneration and synaptogenesis of new 5-HT synapses, especially in the frontal cortex. Similar changes have also been observed after lesions along the ascending projection of the 5-HT neurons of the raphe nuclei (Azmitia and WhitakerAzmitia 1991;Tsuiki et al 1995;Ljubic-Thibal et al 1996)). Such lesion-induced sprouting and regeneration of 5-HT networks has been shown to result in the formation of new synapses and the functional recovery of 5-HT afferents in the denervated projection fields (Wuttke et al 1977).…”

Section: Discussionsupporting

confidence: 55%

Chronic administration of citalopram in olfactory bulbectomy rats restores brain 5-HT synthesis rates: an autoradiographic study

et al. 2004

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There is no significant global or individual structure difference in the synthesis between the Sham-CTP and OBX-CTP groups. The similarity in the synthesis between the OBX-CTP, Sham-CTP and Sham-SAL groups is likely a result of changes in the sensitivity of the receptors through which 5-HT synthesis is controlled. Because of some of the differences in the synthesis between the Sham-CTP and Sham-SAL groups, the data suggest that receptors throughout the brain are not fully desensitized.

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Section: Discussionsupporting

confidence: 55%

Chronic administration of citalopram in olfactory bulbectomy rats restores brain 5-HT synthesis rates: an autoradiographic study

et al. 2004

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“…These changes are probably due to the loss of the negative feedback regulation exerted on TPH level and activity by the end-product 5-HT. We have shown previously that the DHL lesion produces a rather extended ipsilateral increase in TPH activity and 5-HT synthesis rate (Ljubic-Thibal et al, 1996a;Tsuiki et al, 1995). The increase in 5-HT synthesis could be due in part to an increase in TPH activity but also, as demonstrated here, to an increase in newly synthesized TPH protein in serotonergic neurons that reacted to the lesion by upregulating TPH mRNA.…”

Section: Discussionmentioning

confidence: 58%

“…Moreover, the results show that serotonergic neurons whose terminal fields have been locally and selectively damaged upregulate TPH mRNA expression, and are likely to maintain adequate levels of 5-HT within the lesioned area. This compensatory change results in an increased level of TPH protein not only in the projection neurons but also in the axonal pathway, as documented previously by an increased TPH protein level in the medial forebrain bundle (Ljubic-Thibal et al, 1996a). These changes are probably due to the loss of the negative feedback regulation exerted on TPH level and activity by the end-product 5-HT.…”

Section: Discussionmentioning

confidence: 72%

“…In a recent study, we observed that the in vivo steady-state levels of TPH protein selectively increase ipsilaterally in the medial forebrain bundle and discretely in a subset of DR neurons in rats subjected to a 5,7-DHT lesion of serotonergic terminals in the DLH (Ljubic-Thibal et al, 1996a). We interpreted these findings as evidence that a localized disruption in 5-HT projections would induce changes in the projection neurons as an attempt to maintain adequate levels of 5-HT at the terminal area.…”

Section: Introductionmentioning

confidence: 98%

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Origin of the serotonergic innervation to the rat dorsolateral hypothalamus: Retrograde transport of cholera toxin and upregulation of tryptophan hydroxylase mRNA expression following selective nerve terminals lesion

Ljubic‐Thibal

Morin

Dikšić

et al. 1999

Synapse

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The regulation of serotonin synthesis was investigated in the serotonergic neurons, which provide afferents to the dorsolateral hypothalamus (DLH). The origin of the DLH projection neurons within the raphe nucleus was identified by retrograde transport of Cholera toxin (CTb) and their serotonergic nature confirmed by tryptophan hydroxylase (TPH) immunocytochemistry. Disruption of serotonin synthesis steady-state was induced unilaterally by a selective and local destruction of serotonergic nerve terminals with 5,7-dihydroxytryptamine (5,7-DHT), stereotaxically injected in the right DLH. The results show that most of the serotonergic dorsal raphe neurons projecting to the DLH have an ipsilateral localization within the lateral aspects of the nucleus. In rats with unilateral DLH lesion, a population of serotonergic cells within the raphe nucleus exhibited a clear increase in TPH mRNA. These cells were about five times more numerous in the ipsilateral as compared to the contralateral dorsal raphe nucleus and they had, for the most part, a lateral localization within the raphe nucleus. Sham-operated rats did not exhibit any upregulation of TPH mRNA. Together, the present results provide the first demonstration that a discreet and selective destruction of serotonergic terminals induces a circumscribed and striking increase in TPH mRNA expression in a subset of brainstem serotonergic neurons projecting to and/or passing through the DLH. On the basis of these results and previous in vivo measurements of TPH activity (e.g., 5-HT synthesis), we suggest that this upregulation in TPH mRNA expression results from the loss of pre-synaptic and/or post-synaptic regulation of serotonin synthesis. These new findings raise important issues related to the repercussions of a local disruption in serotonergic neurotransmission on brain areas remote from the site of injury.

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“…Serotonergic neurons in the DRND/L project to several structures of the central visual system including the dLGN, superior colliculus, and primary visual cortex where serotonin actively shapes the responses property of visual system networks 19 . In addition, serotonergic neurons in the DRND/L appear to exert inhibitory control over serotonergic projection neurons in the dorsal (DRD) and ventral (DRV) DRN subgroups, acting as serotonergic interneurons 11 56 . Thus, although the retinoraphe projection is strongest to the DRND/L, DRN-projecting RGCs may modulate the activity serotonergic neurons in other regions of the DRN either by direct input or indirectly via serotonergic and GABAergic interneurons thereby contributing to the serotonergic modulation of diverse processes.…”

Section: Discussionmentioning

confidence: 99%

ON and OFF retinal ganglion cells differentially regulate serotonergic and GABAergic activity in the dorsal raphe nucleus

Zhang

Huang

Zhang

et al. 2016

Sci Rep

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The dorsal raphe nucleus (DRN), the major source of serotonergic input to the forebrain, receives excitatory input from the retina that can modulate serotonin levels and depressive-like behavior. In the Mongolian gerbil, retinal ganglion cells (RGCs) with alpha-like morphological and Y-like physiological properties innervate the DRN with ON DRN-projecting RGCs out numbering OFF DRN-projecting RGCs. The DRN neurons targeted by ON and OFF RGCs are unknown. To explore retino-raphe anatomical organization, retinal afferents labeled with Cholera toxin B were examined for association with the postsynaptic protein PSD-95. Synaptic associations between retinal afferents and DRN serotonergic and GABAergic neurons were observed. To explore retino-raphe functional organization, light-evoked c-fos expression was examined. Light significantly increased the number of DRN serotonergic and GABAergic cells expressing c-Fos. When ON RGCs were rendered silent while enhancing the firing rate of OFF RGCs, c-Fos expression was greatly increased in DRN serotonergic neurons suggesting that OFF DRN-projecting RGCs predominately activate serotonergic neurons whereas ON DRN-projecting RGCs mainly target GABAergic neurons. Direct glutamatergic retinal input to DRN 5-HT neurons contributes to the complex excitatory drive regulating these cells. Light, via the retinoraphe pathway can modify DRN 5-HT neuron activity which may play a role in modulating affective behavior.

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Ipsilateral alterations in tryptophan hydroxylase activity in rat brain after hypothalamic 5,7-di-hydroxytryptamine lesion

Cited by 7 publications

References 29 publications

Chronic administration of citalopram in olfactory bulbectomy rats restores brain 5-HT synthesis rates: an autoradiographic study

Chronic administration of citalopram in olfactory bulbectomy rats restores brain 5-HT synthesis rates: an autoradiographic study

Origin of the serotonergic innervation to the rat dorsolateral hypothalamus: Retrograde transport of cholera toxin and upregulation of tryptophan hydroxylase mRNA expression following selective nerve terminals lesion

ON and OFF retinal ganglion cells differentially regulate serotonergic and GABAergic activity in the dorsal raphe nucleus

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