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Reverse Pharmacology on Corydalis yanhusuo: Dehydrocorybulbine, Analgesia and Antipsychosis And Methionine-induced Animal Models of Schizophrenia

Wang, Lien
Advisor(s): Civelli, Olivier

UC Irvine Electronic Theses and Dissertations (2015)

In the first part of the dissertation, a traditional Chinese medicine, Corydalis yanhusuo, which is widely used for pain treatment, was systematically evaluated in three standardized pain assays and its mechanism of action in terms of antinociceptive effects was further studied. The results show that Corydalis yanhusuo extract effectively attenuates acute nociceptive pain, persistent inflammatory pain and chronic neuropathic pain, without causing tolerance. The effects on acute and neuropathic pain but not inflammatory pain are at least partially mediated through dopamine D2 receptor antagonism.

By applying pharmacological approach which is used to identify compounds acting at G protein-coupled receptors, one compound, dehydrocorybulbine (DHCB) was identified from Corydalis yanhusuo extact. DHCB was synthesized and it is shown displaying weak μ-opioid receptor agonist and moderate dopamine receptor antagonist activities. DHCB is effective at alleviating thermally induced acute pain. By using selective pharmacological compounds and dopamine receptor knockout mice, the results show that the antinociceptive effect relies upon DHCB’s antagonist activity at the dopamine D2 receptor but not on its agonist activity at μ-opioid receptor. DHCB is further demonstrated to be effective against inflammatory pain and injury-induced neuropathic pain and furthermore causes no antinociceptive tolerance.

Moreover, the antipsychotic effects of DHCB were evaluated by using apomorphine and MK-801 induced schizophrenia-like symptoms in mice and the extended pharmacological profile of DHCB was screened through radioligand receptor binding assays. DHCB is shown effectively attenuating positive, negative and cognitive symptoms in apomorphine and MK-801 induced animal models of schizophrenia. These effects are thought to be mediated through dopamine receptor antagonism but also other receptor activities such as serotonin-7 and sigma-1 receptors.

In the second part of the dissertation, administration of l-methionine to adult mice for 7 days induces behavioral responses that reflect three types of schizophrenia-like symptoms. These responses are differentially reversed by typical and atypical antipsychotics in ways that parallel their effects in schizophrenics. Further, the male offspring from the prenatal l-methionine treatment exhibit behavioral responses that reflect three types of schizophrenia-like symptoms. Moreover, these mice show reduced excitatory synaptic connection and dysregulated expression of several neuronal activity-regulated genes that are known to be involved in the neurodevelopment, synaptic plasticity and learning and memory function.

Cover page: Reverse Pharmacology on Corydalis yanhusuo: Dehydrocorybulbine, Analgesia and Antipsychosis And Methionine-induced Animal Models of Schizophrenia

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Peer Reviewed

Identification of Neuropeptide Receptors Expressed by Melanin-Concentrating Hormone Neurons

UC Irvine Previously Published Works (2014)

Article
Peer Reviewed

Identification of neuropeptide receptors expressed by melanin‐concentrating hormone neurons

UC Irvine Previously Published Works (2014)

Melanin-concentrating hormone (MCH) is a 19-amino-acid cyclic neuropeptide that acts in rodents via the MCH receptor 1 (MCHR1) to regulate a wide variety of physiological functions. MCH is produced by a distinct population of neurons located in the lateral hypothalamus (LH) and zona incerta (ZI), but MCHR1 mRNA is widely expressed throughout the brain. The physiological responses and behaviors regulated by the MCH system have been investigated, but less is known about how MCH neurons are regulated. The effects of most classical neurotransmitters on MCH neurons have been studied, but those of most neuropeptides are poorly understood. To gain insight into how neuropeptides regulate the MCH system, we investigated which neuropeptide receptors are expressed by MCH neurons by using double in situ hybridization. In all, 20 receptors, selected based on either a suspected interaction with the MCH system or demonstrated high expression levels in the LH and ZI, were tested to determine whether they are expressed by MCH neurons. Overall, 11 neuropeptide receptors were found to exhibit significant colocalization with MCH neurons: nociceptin/orphanin FQ opioid receptor (NOP), MCHR1, both orexin receptors (ORX), somatostatin receptors 1 and 2 (SSTR1, SSTR2), kisspeptin recepotor (KissR1), neurotensin receptor 1 (NTSR1), neuropeptide S receptor (NPSR), cholecystokinin receptor A (CCKAR), and the κ-opioid receptor (KOR). Among these receptors, six have never before been linked to the MCH system. Surprisingly, several receptors thought to regulate MCH neurons displayed minimal colocalization with MCH, suggesting that they may not directly regulate the MCH system.

Article
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Inactivation of the melanin concentrating hormone system impairs maternal behavior

UC Irvine Previously Published Works (2016)

In order to prepare the mother for the demands of pregnancy and lactation, the maternal brain is subjected to a number of adaptations. Maternal behaviors are regulated by complex neuronal interactions. Here, we show that the melanin concentrating hormone (MCH) system is an important regulator of maternal behaviors. First, we report that melanin concentrating hormone receptor 1 knockout (MCHR1 KO) mice display a disruption of maternal behavior. Early postpartum MCHR1 KO females exhibit poor nesting, deficits in pup retrieval and maternal aggression. In addition, ablation of MCH receptors results in decreased milk production and prolactin mRNA levels. Then we show that these results are in line with those obtained in wild type mice (WT) treated with the specific MCHR1 antagonist GW803430. Furthermore, following pups retrieval, MCHR1 KO mice display a lower level of Fos expression than WT mice in the ventral tegmental area, and nucleus accumbens. With the progression of the lactation period, however, the MCHR1 KO mice improve maternal care towards their pups. This is manifested by an increase in the pups׳ survival rate and the decrease in pups׳ retrieval time beyond the second day after parturition. In conclusion, we show that the MCH system plays a significant role in the initiation of maternal behavior. In this context, MCH may play a role in integrating information from multiple sources, and connecting brain reward, homeostatic and regulatory systems.

Cover page: Inactivation of the melanin concentrating hormone system impairs maternal behavior

Article
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A Methionine-Induced Animal Model of Schizophrenia: Face and Predictive Validity

UC Irvine Previously Published Works (2015)

Modulating the methylation process induces broad biochemical changes, some of which may be involved in schizophrenia. Methylation is in particular central to epigenesis, which is also recognized as a factor in the etiology of schizophrenia. Because methionine administration to patients with schizophrenia has been reported to exacerbate their psychotic symptoms and because mice treated with methionine exhibited social deficits and prepulse inhibition impairment, we investigated whether methionine administration could lead to behavioral changes that reflect schizophrenic symptoms in mice. l-Methionine was administered to mice twice a day for 7 days. We found that this treatment induces behavioral responses that reflect the 3 types of schizophrenia-like symptoms (positive, negative, or cognitive deficits) as monitored in a battery of behavioral assays (locomotion, stereotypy, social interaction, forced swimming, prepulse inhibition, novel object recognition, and inhibitory avoidance). Moreover, these responses were differentially reversed by typical haloperidol and atypical clozapine antipsychotics in ways that parallel their effects in schizophrenics. We thus propose the l-methionine treatment as an animal model recapitulating several symptoms of schizophrenia. We have established the face and predictive validity for this model. Our model relies on an essential natural amino acid and on an intervention that is relatively simple and time effective and may offer an additional tool for assessing novel antipsychotics.

Cover page: A Methionine-Induced Animal Model of Schizophrenia: Face and Predictive Validity

Article
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Histamine inhibits the melanin‐concentrating hormone system: implications for sleep and arousal

UC Irvine Previously Published Works (2014)

Melanin-concentrating hormone (MCH)-producing neurons are known to regulate a wide variety of physiological functions such as feeding, metabolism, anxiety and depression, and reward. Recent studies have revealed that MCH neurons receive projections from several wake-promoting brain regions and are integral to the regulation of rapid eye movement (REM) sleep. Here, we provide evidence in both rats and mice that MCH neurons express histamine-3 receptors (H3R), but not histamine-1 (H1R) or histamine-2 (H2R) receptors. Electrophysiological recordings in brain slices from a novel line of transgenic mice that specifically express the reporter ZsGreen in MCH neurons show that histamine strongly inhibits MCH neurons, an effect which is TTX insensitive, and blocked by the intracellular presence of GDP-β-S. A specific H3R agonist, α-methylhistamine, mimicks the inhibitory effects of histamine, and a specific neutral H3R antagonist, VUF 5681, blocks this effect. Tertiapin Q (TPQ), a G protein-dependent inwardly rectifying potassium (GIRK) channel inhibitor, abolishes histaminergic inhibition of MCH neurons. These results indicate that histamine directly inhibits MCH neurons through H3R by activating GIRK channels and suggest that that inhibition of the MCH system by wake-active histaminergic neurons may be responsible for silencing MCH neurons during wakefulness and thus may be directly involved in the regulation of sleep and arousal.

Cover page: Histamine inhibits the melanin‐concentrating hormone system: implications for sleep and arousal

Article
Peer Reviewed

Melanin concentrating hormone modulates oxytocin-mediated marble burying

UC Irvine Previously Published Works (2018)

Repetitive and perseverative behaviors are common features of a number of neuropsychiatric diseases such as Angelman's syndrome, Tourette's syndrome, obsessive-compulsive disorder, and autism spectrum disorders. The oxytocin system has been linked to the regulation of repetitive behavior in both animal models and humans, but many of its downstream targets have still to be found. We report that the melanin-concentrating hormone (MCH) system is a target of the oxytocin system in regulating one repetitive behavior, marble burying. First we report that nearly 60% of MCH neurons express oxytocin receptors, and demonstrate using rabies mediated tract tracing that MCH neurons receive direct presynaptic input from oxytocin neurons. Then we show that MCH receptor knockout (MCHR1KO) mice and MCH ablated animals display increased marble burying response while central MCH infusion decreases it. Finally, we demonstrate the downstream role of the MCH system on oxytocin mediated marble burying by showing that central infusions of MCH and oxytocin alone or together reduce it while antagonizing the MCH system blocks oxytocin-mediated reduction of this behavior. Our findings reveal a novel role for the MCH system as a mediator of the role of oxytocin in regulating marble-burying behavior in mice.

Article
Peer Reviewed

Melanin concentrating hormone modulates oxytocin-mediated marble burying.

UC Irvine Previously Published Works (2018)

Repetitive and perseverative behaviors are common features of a number of neuropsychiatric diseases such as Angelman's syndrome, Tourette's syndrome, obsessive-compulsive disorder, and autism spectrum disorders. The oxytocin system has been linked to the regulation of repetitive behavior in both animal models and humans, but many of its downstream targets have still to be found. We report that the melanin-concentrating hormone (MCH) system is a target of the oxytocin system in regulating one repetitive behavior, marble burying. First we report that nearly 60% of MCH neurons express oxytocin receptors, and demonstrate using rabies mediated tract tracing that MCH neurons receive direct presynaptic input from oxytocin neurons. Then we show that MCH receptor knockout (MCHR1KO) mice and MCH ablated animals display increased marble burying response while central MCH infusion decreases it. Finally, we demonstrate the downstream role of the MCH system on oxytocin mediated marble burying by showing that central infusions of MCH and oxytocin alone or together reduce it while antagonizing the MCH system blocks oxytocin-mediated reduction of this behavior. Our findings reveal a novel role for the MCH system as a mediator of the role of oxytocin in regulating marble-burying behavior in mice.

Article
Peer Reviewed

The Antinociceptive Properties of the Corydalis yanhusuo Extract.

UC Irvine Previously Published Works (2016)

Corydalis yanhusuo. W.T. extracts (YHS) are widely used for the treatment of pain and inflammation. There are a few studies that assessed the effects of YHS in pain assays; however, none of these studies has systematically compared its activities in the different pain animal modes namely: acute, inflammatory and chronic pain. Furthermore, little is known about the mechanism of YHS activity in these assays. The aim of this study was to systematically evaluate the antinociceptive properties of YHS by testing it in four standardized pain assays and to investigate its mechanism. YHS antinociceptive properties were analyzed in the tail flick, the formalin paw licking, the von Frey filament and the hot box assays after spinal nerve ligation, which monitors acute nociceptive, persistent inflammatory and chronic neuropathic pain, respectively. YHS pharmacological profile was determined by screening it against a battery of G-protein coupled receptors and its mechanism of action was studied using knock-out mice. Our study shows that YHS, at a non-sedative dose, increases the tail flick latency in the tail flick assay without resulting in development of tolerance. YHS also decreases paw licking time in the formalin assay. Further, YHS increases paw withdraw threshold and latency in the von Frey filament and the hot box assays, respectively. In vitro, YHS exhibits prominent dopamine receptor antagonistic properties. In dopamine D2 receptor knockout mice, its antinociceptive effects are attenuated in acute and neuropathic pain but not inflammatory pain assays. Our results therefore indicate that YHS effectively attenuates acute, inflammatory and neuropathic pain, without causing tolerance. The effects on acute and neuropathic pain, but not inflammatory pain, are at least partially mediated through dopamine D2 receptor antagonism. Since YHS is a dietary supplement commercially available in the United States, our data suggest that it might be a candidate for alternative pain treatment.

Cover page: The Antinociceptive Properties of the Corydalis yanhusuo Extract.

Article
Peer Reviewed

A novel analgesic isolated from a traditional Chinese medicine.

UC Irvine Previously Published Works (2014)

BACKGROUND: Current pain management is limited, in particular, with regard to chronic pain. In an attempt to discover novel analgesics, we combined the approach developed to characterize traditional Chinese medicine (TCM), as part of the herbalome project, with the reverse pharmacology approach aimed at discovering new endogenous transmitters and hormones. RESULTS: In a plant used for centuries for its analgesic properties, we identify a compound, dehydrocorybulbine (DHCB), that is effective at alleviating thermally induced acute pain. We synthesize DHCB and show that it displays moderate dopamine receptor antagonist activities. By using selective pharmacological compounds and dopamine receptor knockout (KO) mice, we show that DHCB antinociceptive effect is primarily due to its interaction with D2 receptors, at least at low doses. We further show that DHCB is effective against inflammatory pain and injury-induced neuropathic pain and furthermore causes no antinociceptive tolerance. CONCLUSIONS: Our study casts DHCB as a different type of analgesic compound and as a promising lead in pain management.

Cover page: A novel analgesic isolated from a traditional Chinese medicine.