Targeting presynaptic H3 heteroreceptor in nucleus accumbens to improve anxiety and obsessive-compulsive-like behaviors Xiao-Yang Zhanga,b,1, Shi-Yu Penga,1,2, Li-Ping Shena,1, Qian-Xing Zhuanga,1,3, Bin Lia,4,5, Shu-Tao Xiea, Qian-Xiao Lia, Ming-Run Shia, Tian-Yu Maa, Qipeng Zhanga,b, Jian-Jun Wanga,b, and Jing-Ning Zhua,b,5 aState Key Laboratory of Pharmaceutical Biotechnology and Department of Physiology, School of Life Sciences, Nanjing University, Nanjing 210023, China; and bInstitute for Brain Sciences, Nanjing University, Nanjing 210023, China Edited by Lily Yeh Jan, University of California, San Francisco, CA, and approved November 9, 2020 (received for review April 30, 2020) Anxiety commonly co‐occurs with obsessive-compulsive disorder compulsive symptoms in OCD patients (9, 10). More importantly, (OCD). Both of them are closely related to stress. However, the deep brain stimulation (DBS) targeting the NAc core has been shared neurobiological substrates and therapeutic targets remain foundtoimproveobsessive-compulsive symptoms and decrease unclear. Here we report an amelioration of both anxiety and OCD ratings of anxiety in patients suffering from treatment-resistant via the histamine presynaptic H3 heteroreceptor on glutamatergic OCD or depression (11, 12). Therefore, NAc core may be a po- afferent terminals from the prelimbic prefrontal cortex (PrL) to the tentialcommonneuralsubstratefor the clinical and neuropatho- nucleus accumbens (NAc) core, a vital node in the limbic loop. The logical overlap between anxiety and OCD. NAc core receives direct hypothalamic histaminergic projections, The NAc core receives dense glutamatergic projections from and optogenetic activation of hypothalamic NAc core histaminer- the limbic system, including the prefrontal cortex, basolateral gic afferents selectively suppresses glutamatergic rather than amygdala (BLA), and ventral hippocampus (vHipp), and inte- GABAergic synaptic transmission in the NAc core via the H3 recep- grates cognitive and affective information to instigate motiva- tor and thus produces an anxiolytic effect and improves anxiety- tional approach behaviors (13, 14). In addition, the NAc core is and obsessive-compulsive-like behaviors induced by restraint regulated by various neuromodulators, such as orexin, seroto- stress. Although the H3 receptor is expressed in glutamatergic af- – NEUROSCIENCE ferent terminals from the PrL, basolateral amygdala (BLA), and nin, and histamine, from several brain regions (15 17). Among ventral hippocampus (vHipp), rather than the thalamus, only the them, central histamine is synthesized and released by the PrL– and not BLA– and vHipp–NAc core glutamatergic pathways among the glutamatergic afferent inputs to the NAc core is respon- Significance sible for co-occurrence of anxiety- and obsessive-compulsive-like be- haviors. Furthermore, activation of the H3 receptor ameliorates Anxiety disorders and obsessive-compulsive disorder (OCD) are anxiety and obsessive-compulsive-like behaviors induced by optoge- highly prevalent and debilitating psychiatric disorders com- netic excitation of the PrL–NAc glutamatergic afferents. These results monly co-occurring in our stressful modern life. Yet the com- demonstrate a common mechanism regulating anxiety- and obsessive- mon effective therapeutic target is still unknown. Here we compulsive-like behaviors and provide insight into the clinical treatment report that activation of the histaminergic afferent system, strategy for OCD with comorbid anxiety by targeting the histamine particularly the histamine H3 receptor, in the nucleus accum- H3 receptor in the NAc core. bens (NAc) core, a vital node in the limbic loop, inhibits gluta- matergic synaptic transmission in the circuit from the prelimbic nucleus accumbens | prelimbic prefrontal cortex | histamine H3 receptor | prefrontal cortex (PrL) to NAc and improves both anxiety- and anxiety | OCD obsessive-compulsive-like behaviors induced by restraint stress. Our results define a common glutamatergic PrL–NAc nxiety disorders and obsessive-compulsive disorder (OCD) circuit involved in both anxiety- and obsessive-compulsive-like Aare disabling psychiatric conditions and the major contrib- behaviors modulated by the H3 presynaptic heteroreceptor utors to global burden of nonfatal illness (1). OCD is charac- and pave a path for developing potential strategies for clinical terized by recurrent thoughts (obsessions) and/or repetitive treatment of anxiety and OCD. behaviors (compulsions) that are aimed at reducing the anxiety caused by obsessions (2, 3), indicating a close correlation be- Author contributions: B.L. and J.-N.Z. designed research; X.-Y.Z., S.-Y.P., L.-P.S., Q.-X.Z., B.L., S.-T.X., Q.-X.L., M.-R.S., and T.-Y.M. performed research; X.-Y.Z., S.-Y.P., L.-P.S., B.L., tween anxiety and OCD. Indeed, anxiety disorders have been and Q.Z. analyzed data; and X.-Y.Z., S.-Y.P., B.L., J.-J.W., and J.-N.Z. wrote the paper. reported epidemiologically as the most frequent comorbid con- The authors declare no competing interest. ditions with OCD (3, 4). Therefore, common pathologies may be This article is a PNAS Direct Submission. present in anxiety disorders and OCD, and elucidation of the This open access article is distributed under Creative Commons Attribution-NonCommercial- shared neural substrates will lead to greater insight into their NoDerivatives License 4.0 (CC BY-NC-ND). pathophysiology and treatment. 1X.-Y.Z., S.-Y.P., L.-P.S., and Q.-X.Z. contributed equally to this work. The nucleus accumbens (NAc) is a main component of the 2Present address: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental ventral striatum and a pivotal node in limbic basal ganglia loop, Health Center, Shanghai Jiaotong University School of Medicine, Shanghai 200030, whose dysfunction may result in psychiatric diseases such as China. anxiety and OCD (5, 6). Accumulating experimental and clinical 3Present address: Department of Physiology, School of Medicine, Co-innovation Center of evidence indicates that the NAc, particularly the core compart- Neuroregeneration, Nantong University, Nantong 226001, China. ment, holds a key position in motivation, emotion, and cognition 4Present address: Women & Children Central Laboratory, The First Affiliated Hospital of and is strongly implicated in the psychopathology and treatment Nanjing Medical University, Nanjing 210029, China. of anxiety and OCD. It has been reported that trait anxiety and 5To whom correspondence may be addressed. Email: [email protected] or [email protected]. OCD risk are positively correlated with the volume of NAc (7, This article contains supporting information online at https://www.pnas.org/lookup/suppl/ 8). Functional neuroimaging reveals that the NAc activation cor- doi:10.1073/pnas.2008456117/-/DCSupplemental. relates positively with the severity of human anxiety and obsessive- www.pnas.org/cgi/doi/10.1073/pnas.2008456117 PNAS Latest Articles | 1of10 Downloaded by guest on September 28, 2021 histaminergic neurons restrictedly concentrated in the tuber- Results omammillary nucleus (TMN) of the hypothalamus and serves as Histaminergic Afferents in the NAc Core and Involvement of a general modulator for whole-brain activity via the mediation of Histamine H3 Receptor in Anxiety-Related Behaviors. To determine histamine H1 to H4 receptors (18, 19). Accordingly, the aberrant whether the hypothalamic histaminergic neurons directly project histamine signaling is closely associated with sleep, motor, cog- to the NAc core, we delivered anterograde tracer BDA by ion- nitive, and psychiatric conditions (18, 20, 21). In the clinic, drugs tophoresis into the hypothalamic TMN, the sole origin of the targeting the presynaptic H3 receptor have been used for pre- central histaminergic system (Fig. 1 A–C). As shown in Fig. 1D, 1 scribed treatment of various psychiatric and neurologic disorders to G, 3, BDA/histamine double-labeled fibers were observed in (22). Interestingly, a high density of the H3 receptor has been the NAc core, which possessed prominent varicosities and passed found in NAc (23, 24). Therefore, in the present study, we create around GAD67-labeled NAc core neurons. The result indicates a transgenic rat strain expressing Cre recombinase in histidine a possible modulation of histamine released from varicosities of decarboxylase (HDC, the histamine-synthesizing enzyme) neu- hypothalamic histaminergic afferents on GABAergic principle/ rons and employ anterograde axonal tract tracings, whole-cell projection neurons in the NAc core. patch clamp recordings, optogenetic and chemogenetic manip- Next, we employed Western blot to detect the expression of ulation, and behavioral tests to explore the role of hypothalamic histamine H3 receptor proteins in the NAc core. We found that histaminergic afferents and the H3 receptor in the NAc core in the expression of the H3 receptor in the NAc core was only regulation of anxiety and obsessive-compulsive-like behaviors. slightly less than that in the vestibular nuclei (Fig. 1H), where the We find that optogenetic activation of hypothalamic TMN–NAc H3 receptor is expressed very highly (24), indicating a high ex- core histaminergic projections produces an anxiolytic effect and pression of the H3 receptor in the NAc core. Furthermore, bi- ameliorates obsessive-compulsive-like behaviors induced by re- lateral microinjection of histamine into the NAc core significantly straint stress, which is due to H3 receptor–mediated suppression increased the time spent in the open arm