Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of neonatal exposure to excitotoxins on the development of interneurons have not been well characterized, but may be relevant to the pathogenesis of neuropsychiatric disorders. In this study, the excitotoxin, kainic acid (KA) was administered to rats at postnatal day 7 (P7) by intracerebroventricular (i.c.v.) infusion. At P14, P25, P40 and P60, Nissl staining and immunohistochemical studies with the interneuron markers, glutamic acid decarboxylase (GAD-67), calbindin-D28k (CB) and parvalbumin (PV) were performed in the hippocampus. In control animals, the total number of interneurons, as well as the number of interneurons stained with GAD-67, CB and PV, was nearly constant from P14 through P60. In KA-treated rats, Nissl staining, GAD-67 staining, and CB staining revealed a progressive decline in the overall number of interneurons in the CA1 and CA3 subfields from P14 to P60. In contrast, PV staining in KA-treated rats showed initial decreases in the number of interneurons in the CA1 and CA3 subfields at P14 followed by increases that approached control levels by P60. These results suggest that, in general, early exposure to the excitotoxin KA decreases the number of hippocampal interneurons, but has a more variable effect on the specific population of interneurons labeled by PV. The functional impact of these changes may be relevant to the pathogenesis of neuropsychiatric disorders, such as schizophrenia.
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PMID:Intracerebroventricular kainic acid administration to neonatal rats alters interneuron development in the hippocampus. 1451 96

Cannabis use during adolescence is associated with an increased risk for schizophrenia and other disorders. The neuronal basis is unclear, but prefrontal cortical mechanisms have been implicated. Here, we investigated developmental changes in the endocannabinoid system by assessing expression and function of the CB1 cannabinoid receptor in prefrontal and other cortical areas in juvenile (postnatal day 25, P25), adolescent (P40), and adult (P70) rats. Overall, the expression of CB1 receptors in the cortex is highest in juveniles and drops thereafter toward adult levels. However, CB1 receptor expression follows distinct developmental trajectories in different cortical areas. The most pronounced and progressive decrease in CB1 expression was observed in medial prefrontal and other limbic/associative regions. In contrast, major changes in sensorimotor cortices occurred only after P40. We also assessed electrophysiological measures of CB1 receptor function and found that CB1-dependent inhibition of synaptic transmission in the prefrontal cortex follows the same developmental trajectory as observed for receptor expression. Together, these findings indicate that CB1 receptor-mediated signaling decreases during development but is differentially regulated in limbic/associative vs. sensorimotor systems. Therefore, cannabis use during adolescence likely differentially affects limbic/associative and sensorimotor cortical circuits.
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PMID:Differential developmental trajectories for CB1 cannabinoid receptor expression in limbic/associative and sensorimotor cortical areas. 2068 6

A developmental disruption of prefrontal cortical inhibitory circuits is thought to contribute to the adolescent onset of cognitive deficits observed in schizophrenia. However, the developmental mechanisms underlying such a disruption remain elusive. The goal of this study is to examine how repeated exposure to the NMDA receptor antagonist dizocilpine maleate (MK-801) during periadolescence [from postnatal day 35 (P35) to P40] impacts the normative development of local prefrontal network response in rats. In vivo electrophysiological analyses revealed that MK-801 administration during periadolescence elicits an enduring disinhibited prefrontal local field potential (LFP) response to ventral hippocampal stimulation at 20 Hz (beta) and 40 Hz (gamma) in adulthood (P65-P85). Such a disinhibition was not observed when MK-801 was given during adulthood, indicating that the periadolescent transition is indeed a sensitive period for the functional maturation of prefrontal inhibitory control. Accordingly, the pattern of prefrontal LFP disinhibition induced by periadolescent MK-801 treatment resembles that observed in the normal P30-P40 prefrontal cortex (PFC). Additional pharmacological manipulations revealed that these developmentally immature prefrontal responses can be mimicked by single microinfusion of the GABA(A) receptor antagonist picrotoxin into the normal adult PFC. Importantly, acute administration of the GABA(A)-positive allosteric modulator Indiplon into the PFC reversed the prefrontal disinhibitory state induced by periadolescent MK-801 to normal levels. Together, these results indicate a critical role of NMDA receptors in regulating the periadolescent maturation of GABAergic networks in the PFC and that pharmacologically induced augmentation of local GABA(A)-receptor-mediated transmission is sufficient to overcome the disinhibitory prefrontal state associated with the periadolescent MK-801 exposure.
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PMID:Periadolescent exposure to the NMDA receptor antagonist MK-801 impairs the functional maturation of local GABAergic circuits in the adult prefrontal cortex. 2328 19

The maturation of inhibitory circuits during adolescence may be tied to the onset of mental health disorders such as schizophrenia. Neurotrophin signaling likely plays a critical role in supporting inhibitory circuit development and is also implicated in psychiatric disease. Within the neocortex, subcircuits may mature at different times and show differential sensitivity to neurotrophin signaling. We measured miniature inhibitory and excitatory postsynaptic currents (mIPSCs and mEPSCs) in Layer 5 cell-types in the mouse anterior cingulate (Cg) across the periadolescent period. We differentiated cell-types mainly by Thy1 YFP transgene expression and also retrobead injection labeling in the contralateral Cg and ipsilateral pons. We found that YFP- neurons and commissural projecting neurons had lower frequency of mIPSCs than neighboring YFP+ neurons or pons projecting neurons in juvenile mice (P21-25). YFP- neurons and to a lesser extent commissural projecting neurons also showed a significant increase in mIPSC amplitude during the periadolescent period (P21-25 vs. P40-50), which was not seen in YFP+ neurons or pons projecting neurons. Systemic disruption of tyrosine kinase receptor B (TrkB) signaling during P23-50 in TrkBF616A mice blocked developmental changes in mIPSC amplitude, without affecting miniature excitatory post synaptic currents (mEPSCs). Our data suggest that the maturation of inhibitory inputs onto Layer 5 pyramidal neurons is cell-type specific. These data may inform our understanding of adolescent brain development across species and aid in identifying candidate subcircuits that may show greater vulnerability in mental illness.
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PMID:Adolescent maturation of inhibitory inputs onto cingulate cortex neurons is cell-type specific and TrkB dependent. 2576 98

Growing evidence points to a disruption of cortico-thalamo-cortical circuits in schizophrenia (SZ) and bipolar disorder (BD). Clues for a specific involvement of the thalamic reticular nucleus (TRN) come from its unique neuronal characteristics and neural connectivity, allowing it to shape the thalamo-cortical information flow. A direct involvement of the TRN in SZ and BD has not been tested thus far. We used a combination of human postmortem and rodent studies to test the hypothesis that neurons expressing parvalbumin (PV neurons), a main TRN neuronal population, and associated Wisteria floribunda agglutinin-labeled perineuronal nets (WFA/PNNs) are altered in SZ and BD, and that these changes may occur early in the course of the disease as a consequence of oxidative stress. In both disease groups, marked decreases of PV neurons (immunoreactive for PV) and WFA/PNNs were observed in the TRN, with no effects of duration of illness or age at onset. Similarly, in transgenic mice with redox dysregulation, numbers of PV neurons and WFA/PNN+PV neurons were decreased in transgenic compared with wild-type mice; these changes were present at postnatal day (P) 20 for PV neurons and P40 for WFA/PNN+PV neurons, accompanied by alterations of their firing properties. These results show profound abnormalities of PV neurons in the TRN of subjects with SZ and BD, and offer support for the hypothesis that oxidative stress may play a key role in impacting TRN PV neurons at early stages of these disorders. We put forth that these TRN abnormalities may contribute to disruptions of sleep spindles, focused attention and emotion processing in these disorders.
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PMID:The thalamic reticular nucleus in schizophrenia and bipolar disorder: role of parvalbumin-expressing neuron networks and oxidative stress. 2918 Jun 72

The fast-spiking parvalbumin (PV) interneurons play a critical role in neural circuit activity and dysfunction of these cells has been implicated in the cognitive deficits typically observed in schizophrenia patients. Due to the high metabolic demands of PV neurons, they are particularly susceptible to oxidative stress. Given the extant literature exploring the pathological effects of oxidative stress on PV cells in cortical regions linked to schizophrenia, we decided to investigate whether PV neurons in other select brain regions, including sub-cortical structures, may be differentially affected by redox dysregulation induced oxidative stress during neurodevelopment in mice with a genetically compromised glutathione synthesis (Gclm KO mice). Our analyses revealed a spatio-temporal sequence of PV cell deficit in Gclm KO mice, beginning with the thalamic reticular nucleus at postnatal day (P) 20 followed by a PV neuronal deficit in the amygdala at P40, then in the lateral globus pallidus and the ventral hippocampus Cornu Ammonis 3 region at P90 and finally the anterior cingulate cortex at P180. We suggest that PV neurons in different brain regions are developmentally susceptible to oxidative stress and that anomalies in the neurodevelopmental calendar of metabolic regulation can interfere with neural circuit maturation and functional connectivity contributing to the emergence of developmental psychopathology.
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PMID:A developmental redox dysregulation leads to spatio-temporal deficit of parvalbumin neuron circuitry in a schizophrenia mouse model. 3085 72