In JoVE (1)
Other Publications (8)
- Trends in Endocrinology and Metabolism: TEM
- Proceedings of the National Academy of Sciences of the United States of America
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- Se Pu = Chinese Journal of Chromatography / Zhongguo Hua Xue Hui
- The Journal of Physiology
- Nature Neuroscience
Articles by Haijiang Cai in JoVE
Mouse Adrenal Chromaffin Cell Isolation Aaron Kolski-Andreaco1, Haijiang Cai2,3, D. Spencer Currle4, K. George Chandy1, Robert H. Chow2,3 1Department of Physiology and Biophysics, University of California, Irvine (UCI), 2Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, 3Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, 4Department of Developmental and Cell Biology, University of California, Irvine (UCI) Adrenal medullary chromaffin cell culture systems are extremely useful for the study of excitation-secretion coupling in an in vitro setting. This protocol illustrates the method used to dissect the adrenals and then isolate the medullary region by stripping away the adrenal cortex. The digestion of the medulla into single chromaffin cells is then demonstrated.
Other articles by Haijiang Cai on PubMed
Mechanisms of Peptide Hormone Secretion Trends in Endocrinology and Metabolism: TEM. Dec, 2006 | Pubmed ID: 17084640 According to the classical view, peptide hormones are stored in large dense-core vesicles that release all of their cargo rapidly and completely when they fuse with and flatten into the plasma membrane. However, recent imaging studies suggest that this view is too simple. Even after vesicles fuse with the plasma membrane, cells might control the rate of dispersal of vesicle cargo - either by modulating the properties of the fusion pore that connects the vesicle lumen to the extracellular solution or by storing cargo in states that disperse slowly in the extracellular space. Understanding these mechanisms is important, owing to the increasing prevalence of diseases, such as type 2 diabetes mellitus, which arise from insufficient secretion of peptide hormones.
Complexin II Plays a Positive Role in Ca2+-triggered Exocytosis by Facilitating Vesicle Priming Proceedings of the National Academy of Sciences of the United States of America. Dec, 2008 | Pubmed ID: 19033464 SNARE-mediated exocytosis is a multistage process central to synaptic transmission and hormone release. Complexins (CPXs) are small proteins that bind very rapidly and with a high affinity to the SNARE core complex, where they have been proposed recently to inhibit exocytosis by clamping the complex and inhibiting membrane fusion. However, several other studies also suggest that CPXs are positive regulators of neurotransmitter release. Thus, whether CPXs are positive or negative regulators of exocytosis is not known, much less the stage in the vesicle life cycle at which they function. Here, we systematically dissect the vesicle stages leading up to exocytosis using a knockout-rescue strategy in a mammalian model system. We show that adrenal chromaffin cells from CPX II knockout mice exhibit markedly diminished releasable vesicle pools (comprising the readily and slowly releasable pools), while showing no change in the kinetics of fusion pore dilation or morphological vesicle docking. Overexpression of WT CPX II-but not of SNARE-binding-deficient mutants-restores the size of the the releasable pools in knockout cells, and in WT cells it markedly enlarges them. Our results show that CPXs regulate the size of the primed vesicle pools and have a positive role in Ca(2+)-triggered exocytosis.
Chronic Nicotine Selectively Enhances Alpha4beta2* Nicotinic Acetylcholine Receptors in the Nigrostriatal Dopamine Pathway The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Oct, 2009 | Pubmed ID: 19812319 These electrophysiological experiments, in slices and intact animals, study the effects of in vivo chronic exposure to nicotine on functional alpha4beta2* nAChRs in the nigrostriatal dopaminergic (DA) pathway. Recordings were made in wild-type and alpha4 nicotinic acetylcholine receptor (nAChR) subunit knock-out mice. Chronic nicotine enhanced methyllycaconitine citrate hydrate-resistant, dihydro-beta-erythroidine hydrobromide-sensitive nicotinic currents elicited by 3-1000 mum ACh in GABAergic neurons of the substantia nigra pars reticulata (SNr), but not in DA neurons of the substantia nigra pars compacta (SNc). This enhancement leads to higher firing rates of SNr GABAergic neurons and consequently to increased GABAergic inhibition of the SNc DA neurons. In the dorsal striatum, functional alpha4* nAChRs were not found on the neuronal somata; however, nicotine acts via alpha4beta2* nAChRs in the DA terminals to modulate glutamate release onto the medium spiny neurons. Chronic nicotine also increased the number and/or function of these alpha4beta2* nAChRs. These data suggest that in nigrostriatal DA pathway, chronic nicotine enhancement of alpha4beta2* nAChRs displays selectivity in cell type and in nAChR subtype as well as in cellular compartment. These selective events augment inhibition of SNc DA neurons by SNr GABAergic neurons and also temper the release of glutamate in the dorsal striatum. The effects may reduce the risk of excitotoxicity in SNc DA neurons and may also counteract the increased effectiveness of corticostriatal glutamatergic inputs during degeneration of the DA system. These processes may contribute to the inverse correlation between tobacco use and Parkinson's disease.
Genetic Dissection of an Amygdala Microcircuit That Gates Conditioned Fear Nature. Nov, 2010 | Pubmed ID: 21068836 The role of different amygdala nuclei (neuroanatomical subdivisions) in processing Pavlovian conditioned fear has been studied extensively, but the function of the heterogeneous neuronal subtypes within these nuclei remains poorly understood. Here we use molecular genetic approaches to map the functional connectivity of a subpopulation of GABA-containing neurons, located in the lateral subdivision of the central amygdala (CEl), which express protein kinase C-Î´ (PKC-Î´). Channelrhodopsin-2-assisted circuit mapping in amygdala slices and cell-specific viral tracing indicate that PKC-Î´(+) neurons inhibit output neurons in the medial central amygdala (CEm), and also make reciprocal inhibitory synapses with PKC-Î´(-) neurons in CEl. Electrical silencing of PKC-Î´(+) neurons in vivo suggests that they correspond to physiologically identified units that are inhibited by the conditioned stimulus, called CEl(off) units. This correspondence, together with behavioural data, defines an inhibitory microcircuit in CEl that gates CEm output to control the level of conditioned freezing.
[Determination of Eight Pesticide Residues in Tea by Liquid Chromatography-tandem Mass Spectrometry and Its Uncertainty Evaluation] Se Pu = Chinese Journal of Chromatography / Zhongguo Hua Xue Hui. Sep, 2012 | Pubmed ID: 23285969 A method was developed for the determination of eight pesticide residues (fipronil, imidacloprid, acetamiprid, buprofezin, triadimefon, triadimenol, profenofos, pyridaben) in tea by liquid chromatography-tandem mass spectrometry. The sample was extracted by accelerated solvent extraction with acetone-dichloromethane (1:1, v/v) as solvent, and the extract was then cleaned-up with a Carb/NH2 solid phase extraction (SPE) column. The separation was performed on a Hypersil Gold C, column (150 mm x 2. 1 mm, 5 microm) and with the gradient elution of acetonitrile and 0. 1% formic acid. The eight pesticides were determined in the modes of electrospray ionization (ESI) and multiple reaction monitoring (MRM). The analytes were quantified by matrix-matched internal standard method for imidacloprid and acetamiprid, by matrix-matched external standard method for the other pesticides. The calibration curves showed good linearity in 1 - 100 microg/L for fipronil, and in 5 -200 microg/L for the other pesticides. The limits of quantification (LOQs, S/N> 10) were 2 p.g/kg for fipronil and 10 microg/kg for the other pesticides. The average recoveries ranged from 75. 5% to 115.0% with the relative standard deviations of 2.7% - 7.7% at the spiked levels of 2, 5, 50 microg/kg for fipronil and 10, 50, 100 microg/kg for the other pesticides. The uncertainty evaluation for the results was carried out according to JJF 1059-1999 "Evaluation and Expression of Uncertainty in Measurement". Items constituting measurement uncertainty involved standard solution, weighing of sample, sample pre-treatment, and the measurement repeatability of the equipment were evaluated. The results showed that the measurement uncertainty is mainly due to sample pre-treatment, standard curves and measurement repeatability of the equipment. The method developed is suitable for the conformation and quantification of the pesticides in tea.
Complexin Facilitates Exocytosis and Synchronizes Vesicle Release in Two Secretory Model Systems The Journal of Physiology. May, 2013 | Pubmed ID: 23401610 Complexins (Cplxs) are small, SNARE-associated proteins believed to regulate fast, calcium-triggered exocytosis. However, studies have pointed to either an inhibitory and/or facilitatory role in exocytosis, and the role of Cplxs in synchronizing exocytosis is relatively unexplored. Here, we compare the function of two types of complexin, Cplx 1 and 2, in two model systems of calcium-dependent exocytosis. In mouse neuromuscular junctions (NMJs), we find that lack of Cplx 1 significantly reduces and desynchronizes calcium-triggered synaptic transmission; furthermore, high-frequency stimulation elicits synaptic facilitation, instead of normal synaptic depression, and the degree of facilitation is highly sensitive to the amount of cytoplasmic calcium buffering. In Cplx 2-null adrenal chromaffin cells, we also find decreased and desynchronized evoked release, and identify a significant reduction in the vesicle pool close to the calcium channels (immediately releasable pool, IRP). Viral transduction with either Cplx 1 or 2 rescues both the size of the evoked response and the synchronicity of release, and it restores the IRP size. Our findings in two model systems are mutually compatible and indicate a role of Cplx 1 and 2 in facilitating vesicle priming, and also lead to the new hypothesis that Cplxs may synchronize vesicle release by promoting coupling between secretory vesicles and calcium channels.
Central Amygdala PKC-δ(+) Neurons Mediate the Influence of Multiple Anorexigenic Signals Nature Neuroscience. Sep, 2014 | Pubmed ID: 25064852 Feeding can be inhibited by multiple cues, including those associated with satiety, sickness or unpalatable food. How such anorexigenic signals inhibit feeding at the neural circuit level is not completely understood. Although some inhibitory circuits have been identified, it is not yet clear whether distinct anorexigenic influences are processed in a convergent or parallel manner. The amygdala central nucleus (CEA) has been implicated in feeding control, but its role is controversial. The lateral subdivision of CEA (CEl) contains a subpopulation of GABAergic neurons that are marked by protein kinase C-δ (PKC-δ). We found that CEl PKC-δ(+) neurons in mice were activated by diverse anorexigenic signals in vivo, were required for the inhibition of feeding by such signals and strongly suppressed food intake when activated. They received presynaptic inputs from anatomically distributed neurons activated by different anorexigenic agents. Our data suggest that CEl PKC-δ(+) neurons constitute an important node that mediates the influence of multiple anorexigenic signals.
Ventromedial Hypothalamic Neurons Control a Defensive Emotion State ELife. 2015 | Pubmed ID: 25748136 Defensive behaviors reflect underlying emotion states, such as fear. The hypothalamus plays a role in such behaviors, but prevailing textbook views depict it as an effector of upstream emotion centers, such as the amygdala, rather than as an emotion center itself. We used optogenetic manipulations to probe the function of a specific hypothalamic cell type that mediates innate defensive responses. These neurons are sufficient to drive multiple defensive actions, and required for defensive behaviors in diverse contexts. The behavioral consequences of activating these neurons, moreover, exhibit properties characteristic of emotion states in general, including scalability, (negative) valence, generalization and persistence. Importantly, these neurons can also condition learned defensive behavior, further refuting long-standing claims that the hypothalamus is unable to support emotional learning and therefore is not an emotion center. These data indicate that the hypothalamus plays an integral role to instantiate emotion states, and is not simply a passive effector of upstream emotion centers.