Project description:AimsAnxiety disorders associated with pain are a common health problem. However, the underlying mechanisms remain poorly understood. We aimed to investigate the role of paraventricular nucleus (PVN)-central nucleus of the amygdala (CeA) oxytocinergic projections in anxiety-like behaviors induced by inflammatory pain.MethodsAfter inflammatory pain induction by complete Freund's adjuvant (CFA), mice underwent elevated plus maze, light-dark transition test, and marble burying test to examine the anxiety-like behaviors. Chemogenetic, optogenetic, and fiber photometry recordings were used to modulate and record the activity of the oxytocinergic projections of the PVN-CeA.ResultsThe key results are as follows: inflammatory pain-induced anxiety-like behaviors in mice accompanied by decreased activity of PVN oxytocin neurons. Chemogenetic activation of PVN oxytocin neurons prevented pain-related anxiety-like behaviors, whereas inhibition of PVN oxytocin neurons induced anxiety-like behaviors in naïve mice. PVN oxytocin neurons projected directly to the CeA, and microinjection of oxytocin into the CeA blocked anxiety-like behaviors. Inflammatory pain also decreased the activity of CeA neurons, and optogenetic activation of PVNoxytocin -CeA circuit prevented anxiety-like behavior in response to inflammatory pain.ConclusionThe results of our study suggest that oxytocin has anti-anxiety effects and provide novel insights into the role of PVNoxytocin -CeA projections in the regulation of anxiety-like behaviors induced by inflammatory pain.
Project description:The supramammillary nucleus (SuM) provides substantial innervation to the dentate gyrus (DG). It remains unknown how the SuM and DG coordinate their activities at the circuit level to regulate spatial memory. Additionally, SuM co-releases GABA and glutamate to the DG, but the relative role of GABA versus glutamate in regulating spatial memory remains unknown. Here we report that SuM-DG Ca2+ activities are highly correlated during spatial memory retrieval as compared to the moderate correlation during memory encoding when mice are performing a location discrimination task. Supporting this evidence, we demonstrate that the activity of SuM neurons or SuM-DG projections is required for spatial memory retrieval. Furthermore, we show that SuM glutamate transmission is necessary for both spatial memory retrieval and highly-correlated SuM-DG activities during spatial memory retrieval. Our studies identify a long-range SuM-DG circuit linking two highly correlated subcortical regions to regulate spatial memory retrieval through SuM glutamate release.
Project description:The lateral hypothalamus (LH) is physiologically critical in brain functions. The LH also plays an important role in drug addiction. However, neural circuits underlying LH involvement of drug addiction remain obscure. In the present study,our results showed that in male mice, during context-induced expression of morphine withdrawal memory, LH glutamatergic neurons played an important role; dopamine D1 receptor-expressing medium spiny neurons (D1-MSNs) projecting from the core of nucleus accumbens (NAcC) to the LH were an important upstream circuit to activate LH glutamatergic neurons; D1-MSNs projecting from the NAcC to the LH activated LH glutamatergic neurons through inhibiting LH local gamma-aminobutyric acid (GABA) neurons. These results suggest that disinhibited LH glutamatergic neurons by neural circuits from the NAcC importantly contribute to context-induced the expression of morphine withdrawal memory.
Project description:The hypothalamic supramammillary nucleus (SuM) projects heavily to the hippocampus to regulate hippocampal activity and plasticity. Although the projections from the SuM to the dentate gyrus (DG) and CA2 have been extensively studied, whether the SuM projects to CA1, the main hippocampal output region, is unclear. Here, we report a glutamatergic pathway from the SuM that selectively excites CA1 interneurons in the border between the stratum radiatum (SR) and the stratum lacunosum-moleculare (SLM). We find that the SuM projects selectively to a narrow band in the CA1 SR/SLM and monosynaptically excites SR/SLM interneurons, including vasoactive intestinal peptide-expressing (VIP+) and neuron-derived neurotrophic factor-expressing (NDNF+) cells, but completely avoids making monosynaptic contacts with CA1 pyramidal neurons (PNs) or parvalbumin-expressing (PV+) or somatostatin-expressing (SOM+) cells. Moreover, SuM activation drives spikes in most SR/SLM interneurons to suppress CA1 PN excitability. Taken together, our findings reveal that the SuM can directly regulate hippocampal output region CA1, bypassing CA2, CA3, and the DG.
Project description:BackgroundSocial recognition memory (SRM) is the ability to distinguish familiar from novel conspecifics and is crucial for survival and reproductive success across social species. We previously reported that oxytocin (OXT) receptor (OXTR) signaling in the CA2/CA3a of dorsal hippocampus is essential to promote the persistence of long-term SRM, yet how the endogenous OXT system influences CA2 outputs to regulate long-term SRM formation remains unclear.MethodsTo achieve a selective deletion of CA2 OXTRs, we crossed Amigo2-Cre mice with Oxtr-floxed mice to generate CA2-specific Oxtr conditional knockout (Oxtr-/-) mice. A three-chamber paradigm test was used for studying SRM in mice. Chemogenetic and optogenetic targeting strategies were employed to manipulate neuronal activity.ResultsWe show that selective ablation of Oxtr in the CA2 suffices to impair the persistence of long-term SRM but has no effect on sociability and social novelty preference in the three-chamber paradigm test. We find that cell-type specific activation of OXT neurons within the hypothalamic paraventricular nucleus enhances long-term SRM and this enhancement is blocked by local application of OXTR antagonist L-368,899 into dorsal hippocampal CA2 (dCA2) region. In addition, chemogenetic neuronal silencing in dCA2 demonstrated that neuronal activity is essential for forming long-term SRM. Moreover, chemogenetic terminal-specific inactivation reveals a crucial role for dCA2 outputs to ventral CA1 (vCA1), but not dorsal lateral septum, in long-term SRM. Finally, targeted activation of the dCA2-to-vCA1 circuit effectively ameliorates long-term SRM deficit observed in Oxtr-/- mice.ConclusionsThese findings highlight the importance of hippocampal CA2 OXTR signaling in governing the persistence of long-term SRM and identify a hippocampal circuit linking dCA2 to vCA1 necessary for controlling long-term SRM formation.
Project description:Nuclear receptor corepressor 1 (NCOR1) and NCOR2 (also known as SMRT) regulate gene expression by activating histone deacetylase 3 through their deacetylase activation domain (DAD). We show that mice with DAD knock-in mutations have memory deficits, reduced anxiety levels, and reduced social interactions. Mice with NCOR1 and NORC2 depletion specifically in GABAergic neurons (NS-V mice) recapitulated the memory deficits and had reduced GABAA receptor subunit α2 (GABRA2) expression in lateral hypothalamus GABAergic (LHGABA) neurons. This was associated with LHGABA neuron hyperexcitability and impaired hippocampal long-term potentiation, through a monosynaptic LHGABA to CA3GABA projection. Optogenetic activation of this projection caused memory deficits, whereas targeted manipulation of LHGABA or CA3GABA neuron activity reversed memory deficits in NS-V mice. We describe de novo variants in NCOR1, NCOR2 or HDAC3 in patients with intellectual disability or neurodevelopmental disorders. These findings identify a hypothalamus-hippocampus projection that may link endocrine signals with synaptic plasticity through NCOR-mediated regulation of GABA signaling.
Project description:Drug-associated conditioned cues promote subjects to recall drug reward memory, resulting in drug-seeking and reinstatement. A consolidated memory becomes unstable after recall, such that the amnestic agent can disrupt the memory during the reconsolidation stage, which implicates a potential therapeutic strategy for weakening maladaptive memories. The basolateral amygdala (BLA) involves the association of conditioned cues with reward and aversive valences and projects the information to the nucleus accumbens (NAc) that mediates reward-seeking. However, whether the BLA-NAc projection plays a role in drug-associated memory reactivation and reconsolidation is unknown. We used methamphetamine (MeAM) conditioned place preference (CPP) to investigate the role of BLA-NAc neural projection in the memory reconsolidation. Two weeks before CPP training, we infused adeno-associated virus (AAV) carrying the designer receptor exclusively activated by designer drugs (DREADD) or control constructs. We infused clozapine-N-oxide (CNO) after the recall test to manipulate the neural activity of BLA-NAc projections in mice. We found that after recall, DREADD-mediated inhibition of BLA neurons projecting to the NAc core blunted consolidated MeAM-associated memory. Inhibition of BLA glutamatergic nerve terminals in the NAc core 1 h after recall disrupted consolidated MeAM-associated memory. However, inhibiting this pathway after the time window of reconsolidation failed to affect memory. Furthermore, under the condition without memory retrieval, DREADD-mediated activation of BLA-NAc core projection was required for amnesic agents to disrupt consolidated MeAM-associated memory. Our findings provide evidence that the BLA-NAc pathway activity is involved in the post-retrieval processing of MeAM-associated memory in CPP.
Project description:BackgroundThe lateral hypothalamus (LHA) is an evolutionarily conserved structure that regulates basic functions of an organism, particularly wakefulness. To clarify the function of LHAGABA neurons and their projections on regulating general anesthesia is crucial for understanding the excitatory and inhibitory effects of anesthetics on the brain. The aim of the present study is to investigate whether LHAGABA neurons play either an inhibitory or a facilitatory role in sevoflurane-induced anesthetic arousal regulation.MethodsWe used fiber photometry and immunofluorescence staining to monitor changes in neuronal activity during sevoflurane anesthesia. Opto-/chemogenetic modulations were employed to study the effect of neurocircuit modulations during the anesthesia. Anterograde tracing was used to identify a GABAergic projection from the LHA to a periaqueductal gray (PAG) subregion.Resultsc-Fos staining showed that LHAGABA activity was inhibited by induction of sevoflurane anesthesia. Anterograde tracing revealed that LHAGABA neurons project to multiple arousal-associated brain areas, with the lateral periaqueductal gray (LPAG) being one of the dense projection areas. Optogenetic experiments showed that activation of LHAGABA neurons and their downstream target LPAG reduced the burst suppression ratio (BSR) during continuous sevoflurane anesthesia. Chemogenetic experiments showed that activation of LHAGABA and its projection to LPAG neurons prolonged the anesthetic induction time and promoted wakefulness.ConclusionsIn summary, we show that an inhibitory projection from LHAGABA to LPAGGABA neurons promotes arousal from sevoflurane-induced loss of consciousness, suggesting a complex control of wakefulness through intimate interactions between long-range connections.
Project description:Evidence in humans suggests that limbic cortices are more active during rapid eye movement (REM or paradoxical) sleep than during waking, a phenomenon fitting with the presence of vivid dreaming during this state. In that context, it seemed essential to determine which populations of cortical neurons are activated during REM sleep. Our aim in the present study is to fill this gap by combining gene expression analysis, functional neuroanatomy, and neurochemical lesions in rats. We find in rats that, during REM sleep hypersomnia compared to control and REM sleep deprivation, the dentate gyrus, claustrum, cortical amygdaloid nucleus, and medial entorhinal and retrosplenial cortices are the only cortical structures containing neurons with an increased expression of Bdnf, FOS, and ARC, known markers of activation and/or synaptic plasticity. Further, the dentate gyrus is the only cortical structure containing more FOS-labeled neurons during REM sleep hypersomnia than during waking. Combining FOS staining, retrograde labeling, and neurochemical lesion, we then provide evidence that FOS overexpression occurring in the cortex during REM sleep hypersomnia is due to projections from the supramammillary nucleus and the claustrum. Our results strongly suggest that only a subset of cortical and hippocampal neurons are activated and display plasticity during REM sleep by means of ascending projections from the claustrum and the supramammillary nucleus. Our results pave the way for future studies to identify the function of REM sleep with regard to dreaming and emotional memory processing.