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The Rice Lab Studies FACTORS THAT GOVERN DYNAMIC, LOCAL DOPAMINE RELEASE.

 

Dopamine (DA) transmission plays a critical role in motor and reward learning through two major pathways connecting the midbrain to the distant striatal complex. The nigrostriatal pathway projects from the substantia nigra pars compacta (SNc) to the dorsal striatum, where the axonal arbor of single DA neuron can extend over 6% of striatal volume. Loss of SNc DA underlies the basal ganglia dysfunction and the motor deficits observed during Parkinson's disease. The parallel mesolimbic pathway projects from the ventral tegmental area (VTA) to the ventral striatum (nucleus accumbens [NAc] shell and core). In the NAc, an increase in the frequency of phasic DA release has been shown to accompany the motivational and reinforcing properties of drugs, food, and other rewarding stimuli.

Within target striatal regions, DA release occurs from DA axons. Notably, however, midbrain DA neurons also release DA from their cell bodies (somata) and dendrites, in a process known as somatodendritic release. Because DA receptors and the DA transporter (DAT) are largely extrasynaptic, DA release relies predominantly on volume transmission and thus depends on regionally dependent diffusion and uptake characteristics.

Research in the Rice Lab is focused on elucidating factors that provide local regulation of axonal and somatodendritic DA release. The primary method in the Rice group to detect DA release is fast-scan cyclic voltammetry (FSCV), complemented by whole-cell patch clamp recording, fluorescence imaging, and immunohistochemistry.  Most studies are conducted in ex vivo rodent brain slices, which are used to provide insight into local regulation of DA release and uptake without the confounding influence of feedback from longer pathways and brain circuits.

Ongoing Projects

 

Insulin is a reward signal that enhances striatal DA release via cholinergic interneurons

 

Striatal DA plays key roles in modulating motor and reward behaviors. DA release from striatal axons is often assumed to be governed exclusively by the firing pattern of midbrain dopamine neurons. However, it is also strongly influenced by local transmitters, especially acetylcholine (ACh) (e.g., Rice and Cragg 2004), as well as by extrinsic factors, like insulin. During and after we eat, we experience a sustained increase in plasma insulin, which activates insulin receptors (InsRs) in the hypothalamus and communicates with appetitive circuits to decrease eating. However, the rising incidence of obesity and Type II diabetes, which results in chronically high levels of insulin, suggests that there may be competitive reward circuitry regulating the motivational and rewarding properties of food.

The nucleus accumbens (NAc) has been shown to mediate the anticipation of rewarding food or drugs, while  the caudate-putamen (CPu) has been proposed to play a role in habit-formation and craving. On-going work in the Rice Lab has shown that insulin can amplify action potential-dependent DA release in the NAc and CPu.

Indeed, ACh-dopamine interactions are central to the influence of peripherally derived insulin in the striatum through an indirect mechanism that involves striatal cholinergic interneurons (ChIs) that express InsRs (Stouffer et al., 2015). At physiological concentrations (nM), insulin enhances evoked DA release in ex vivo striatal slices, monitored using FSCV. This enhancement requires ACh and nAChRs, as the effect is lost in striatal slices from mice with forebrain ACh deletion, or after pharmacological antagonism of nAChRs. Further implicating ChIs in this process, insulin increases ChI excitability via insulin receptors on these cells. The amplification of DA release by insulin suggests a role for this neuropeptide as a reward signal, which complements its well-established role in satiety.

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Insulin receptors (InsRs) on striatal cholinergic interneuron (ChI). Electrophysiologically identified ChI triple labelled for biocyin (red, from the recording pipette), acetylcholine synthesis (blue, choline acetyltransferase, ChAT), and InsRs (gre…

Insulin receptors (InsRs) on striatal cholinergic interneuron (ChI). Electrophysiologically identified ChI triple labelled for biocyin (red, from the recording pipette), acetylcholine synthesis (blue, choline acetyltransferase, ChAT), and InsRs (green). Activation of InsRs increases ChI excitability and enhances release of dopamine, a key reward pathway transmitter. Adapted from Stouffer et al., 2015.

Insulin receptors (InsRs) on a striatal cholinergic interneuron (ChI). ChI identified by immunolabelling acetylcholine synthesis (blue, choline acetyltransferase) expresses InsRs. Activation of InsRs increases ChI excitability and enhances DA releas…

Insulin receptors (InsRs) on a striatal cholinergic interneuron (ChI). ChI identified by immunolabelling acetylcholine synthesis (blue, choline acetyltransferase) expresses InsRs. Activation of InsRs increases ChI excitability and enhances DA release. Adapted from Stouffer et al., 2015.

Insulin boosts striatal dopamine release by activating cholinergic interneurons, and thereby influences food choice.

Insulin boosts striatal dopamine release by activating cholinergic interneurons, and thereby influences food choice.

Companion behavioral studies done in collaboration with Kenneth Carr’s lab at NYU show that intact insulin signaling conveys the nutritive value of what we ingest, and thereby reinforces preference for high sugar substances. Together, these data reveal the key roles of local modulation of dopamine within the striatum in mediating the influence of insulin on motivation. Current studies include addressing the pathways and ion channels involved in activation of ChIs by insulin using whole-cell recording.  We are also working on refining an enzyme electrode to detect ACh.

 

LEPTIN PROMOTES DOPAMINE RELEASE IN THE NIGROSTRIATAL and mesolimbic PATHWAYs

 

Left. Leptin receptor (red) expression in SNc dopamine neurons (blue). Right. Leptin increases the spontaneous activity of SNc dopamine neurons.

Left. Leptin receptor (red) expression in SNc dopamine neurons (blue). Right. Leptin increases the spontaneous activity of SNc dopamine neurons.

Like insulin, leptin (a satiety hormone) also enhances striatal dopamine release in both dorsal and ventral striatum in ex vivo brain slices. In contrast to the effect of exercise, however, the influence of leptin is entirely dependent on the boosting of dopamine release by ACh. Leptin has no effect on dopamine release in slices from mice that lack ACh synthesis, or when ACh receptors are blocked.Further mechanistic studies implicate an increase in intracellular calcium amplifying DA release. On-going studies are investigating the influence of leptin on DA neurons of the substantia nigra, as well as how leptin regulation of DA release changes with exercise. 

    

 The Influence of Exercise on Nigrostriatal and mesolimbic Dopamine Regulation and release

  

Exercise has been shown to increase levels of brain-derived neurotrophic factor (BDNF) in rodent hippocampus. However, the influence of exercise on striatal DA release and its possible regulation by BDNF are poorly understood. Our recent results indicated that mice allowed free access to running wheels for 30 days led to a significant increase in dynamic striatal DA release in brain slices from runners vs. mice with a fixed wheel in their cages. As striatal DA release is potently regulated by another striatal neurotransmitter, acetylcholine (ACh), parallel studies  examined whether the runner/non-runner difference involved indirect boosting by ACh, or whether it was a direct effect on DA axons. These studies showed that higher levels of DA release in runners vs. non-runners persisted when nicotinic ACh receptors were blocked, and thus confirmed a direct effect on DA release. On-going studies include assessing BDNF levels in runners and non-runners.

 

Immunofluorescence staining showing colocalization of tyrosine hydroxylase (labelled in blue) and the SNARE protein SNAP-25 (labelled in red) in both the somata and the dendrites of midbrain dopamine neurons.

Immunofluorescence staining showing colocalization of tyrosine hydroxylase (labelled in blue) and the SNARE protein SNAP-25 (labelled in red) in both the somata and the dendrites of midbrain dopamine neurons.

THE MECHANISM OF SOMATODENDRITIC DA RELEASE FROM DA NEURONS OF THE SUBSTANTIA NIGRA PARS COMPACTA

 

In addition to releasing DA from their striatal axons, midbrain DA neurons in the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) release DA from their cell bodies and dendrites (Patel and Rice 2015; Ludwig et al. 2017). Current work in the Rice Lab is addressing the roles of specific SNARE proteins in the process of somatodendritic DA release.  Consistent with the idea that DA release from a given neuron regulates the activity of that same cell via D2 DA autoreceptors, we find that introduction of botulinum toxin (which cleaves the SNARE protein, SNAP-25) into a recorded DA neuron via a patch-pipette eliminates evoked DA-dependent currents in that cell while preserving the response to an exogenous D2 dopamine receptor agonist.

In related studies, we are using immunohistochemistry to identify subcellular proteins typically involved in dopamine storage or exocytotic release in order to gain insight into the mechanisms behind these processes.

Lastly, in collaboration with Jin Ryoun Kim’s group at the NYU Tandon School of Engineering, we are also examining the influence of different forms of α-synuclein (monomers, oligomers, and fibrils) on DA neuron physiology and somatodendritic DA release. This protein is a key component of Lewy bodies that are pathological hallmarks of Parkinson’s, and may be causally linked to the DA neuron degeneration that leads to the immobility of Parkinson’s disease.

 

Lab Members

 

Lab Alumni

 

 

In Memoriam of Dr. Paul Witkovsky

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Contact Us

 
 
 

Publications


Rice, M.E., Hikima, T., Witkovsky, P., Patel, J.C. (2025) Somatodendritic dopamine release. In Handbook of Dopamine, Chapter 9 pp. 101-113. Eds: S.J. Cragg and M.E. Walton.  

Mancini, M., Hikima, T., Witkovsky, P., Patel, J.C., Stone, D.W., Affinati, A.H., and Rice, M.E. (2025) Leptin activates dopamine and GABA neurons in the substantia nigra via a local pars compacta—pars reticulata circuit. J. Neurosci. 45: e1539242025 (PMID: 40127936; PMCID: PMC12096038). 

Regoni, M.*, Zanetti, L.*, Sevegnani, M., Domenicale, C., Magnabosco, S., Patel, J.C., Fernandes, M.K., Feeley, R.M., Monzani, E., Mini, C., Comai, S., Cherchi, L., De Gregorio, D., Soliman, I., Ruto, F., Croci, L., Consalez, G.G., Rodighiero, S., Ciammola, A, Valtorta, F., Morari, M., Piccoli, G., Rice, M. E., Sassone, J. (2024) Dopamine neuron dysfunction and loss in the PrknR275W mouse model of Juvenile Parkinsonism (*co-first authors). Brain 147: 4017-402; doi:10.1093/brain/awae276 (PMID: 39350737; PCMID: PMC11733804). 

Jamalzadeh M, Cuniberto E, Huang Z, Feeley RM, Patel JC, Rice ME, Uichanco J, Shahrjerdi D (2024) Toward robust quantification of dopamine and serotonin in mixtures using nano-graphitic carbon sensors. Analyst. 149: 2351-2362. doi: 10.1039/d3an02086j. PMID: 38375597  

Patel JC, Sherpa AD, Melani R, Witkovsky P, Wiseman MR, O'Neill B, Aoki C, Tritsch NX, Rice ME (2024) GABA co-released from striatal dopamine axons dampens phasic dopamine release through autoregulatory GABAA receptors Cell Reports 202443: 113834. doi: 10.1016/j.celrep.2024.113834. PMCID: PMC11089423 

Patel JC, Carr KD, Rice ME (2023) Actions and consequences of insulin in the striatum. Biomolecules 13:518. PMCID: PMC10046598 

Bastioli, G., Arnold, J.C., Mancini, M., Mar, A.C., Gamallo-Lana, B., Saadipour, L., Chao, M.V., Rice M.E. (2022) Voluntary Exercise Boosts Striatal Dopamine Release: Evidence for the Necessary and Sufficient Role of BDNF. J. Neurosci. 42: 4725-4736. doi: 10.1523/JNEUROSCI.2273-21.2022.

Hikima, T., Witkovsky, P., Khatri, L., Chao, M.V., Rice, M.E. (2022) Synaptotagmins 1 and 7 Play Complementary Roles in Somatodendritic Dopamine Release. J. Neurosci. 42: 3919-3930. doi: 10.1523/JNEUROSCI.2416-21.2022.

Longo, F., Mancini, M., Ibraheem, P.L., Aryal, S., Mesini, C., Patel, J.C., Penhos, E., Rahman, N., Mamcarz, M., Santini, E., Rice, M.E., Klann, E. (2021) Cell-type-specific disruption of PERK-elF2α signaling in dopaminergic neurons alters motor and cognitive function. Mol. Psychiatry 26: 6427-6450. doi: 10.1038/s41380-021-01099-w.

Hikima, T., Lee, C.R., Witkovsky, P., Chesler, J., Ichtchenko, K., Rice, M.E. (2021) Activity-dependent somatodendritic dopamine release in the substantia nigra autoinhibits the releasing neuron. Cell Rep. 35: 108951. doi: 10.1016/j/celrep.2021.108951.

Rice, M.E. (2019) Closing in on what motivates motivation. Nature 570: 40-42. doi: 10.1038/d41586-019-01589-6.

Patel, J.C., Stouffer, M.A., Nicholson, C., Mancini, M., Carr, K.D., Rice, M.E. (2018) Interactions between insulin and diet on striatal dopamine uptake kinetics in rodent brain slices. Eur. J. Neuroscience 49: 794-804. doi: 10.1111/ejn.13958.

O’Neill, B., Patel, J.C., Rice, M.E. (2017) Characterization of optically and electrically evoked dopamine release in striatal slices from digenic knock-in mice with DAT-driven expression of channelrhodopsin. ACS Chem. Neurosci. 8: 310-319 doi: 10.1021/acschemneuro.6b00300.

Ludwig, M., Apps, D., Menzies, J., Patel, J.C., Rice, M.E. (2017) Dendritic release of neurotransmitters. Compr. Physiol. 7: 235-252.

Rice, M.E. (2017) Monitoring molecules then and now. ACS Chem. Neurosci. 8: 215-217. doi: 10.1021/acschemneuro.7b00043.

Farooq, M., Kim, S., Patel, S., Khatri, L., Hikima, T., Rice, M.E., Ziff, E.B. (2017) Lithium increases synaptic GluA2 in hippocampal neurons by elevating the delta-catenin protein. Neuropharmacology. 113: 426-433.

Asri, R., O’Neill, B., Patel, J.C., Siletti, K.A., Rice, M.E. (2016) Detection of evoked acetylcholine release in mouse striatal brain slices. Analyst 141: 6416-6421.

Sulzer, D., Cragg, S.J., Rice, M.E. (2016) Striatal dopamine neurotransmission: regulation of release and uptake. Basal Ganglia  6: 123-148.

Sulzer, D., Cragg, S.J., Rice, M.E. (2016) Regulation of extracellular dopamine: release and reuptake. In: Handbook of Basal Ganglia Structure and Function. Steiner, H. and Tseng, K.Y. eds. Cambridge, MA: Academic Press ; 373-402

Stouffer, M.A., *Woods, C.A., *Patel, J.C., Lee, C.R., Witkovsky, P., Bao, L., Jones, K.T., Machold, R.P., Cabeza de Vaca, S., Reith, M.E.A, Carr, K.D., Rice, M.E. (2015) Insulin enhances striatal dopamine release by activating cholinergic interneurons and thereby signals reward. Nature Commun. 6: 8543 doi: 10.1038/ncomms9543 (*equal contribution). 

Rice, M.E., Patel, J.C. (2015) Somatodendritic dopamine release: recent mechanistic insights.  Phil. Trans. R. Soc. B. 370: 20140185 (doi: 10.1098/rstb.2014.0185).

Lee, C.R., Patel, J.C, O’Neill, B., Rice, M.E. (2015)  Excitatory and inhibitory neuromodulation by hydrogen peroxide: translating energetics to information. J. Physiol. (Lond.) 593: 3431-3446.

O’Neill, B., Lauterstein, D., Patel, J.C., Zelikoff, J.T, Rice, M.E. (2015) Striatal dopamine release regulation by the cholinergic properties of the smokeless tobacco product, gutkha. ACS Chem. Neurosci. 6: 832-837.

Karayannis, T., Au, E., Patel, J.C., Kruglikov, I., Markx, S., Delorme, R.,  Héron, D., Salomon, D., Glessner, J., Restituito, S., Gordon, A., Rodriguez-Murillo, L., Roy, N.C., Gogos, J., Rudy, B., Rice, M.E., Karayiorgou, M., Hakonarson, H., Keren, B., Huguet, G., Bourgeron, T., Hoeffer, C., Tsien, R.W., Peles, E., Fishell, G. (2014) Cntnap4 differentially contributes to GABAergic and dopaminergic synaptic transmission. Nature 511: 236-240.

Patel, J.C., Rice, M.E. (2013) Monitoring axonal and somatodendritic dopamine release using fast-scan cyclic voltammetry in brain slices. Methods Mol. Biol. 964: 243-273.

Lee, C.R., Machold, R.P., Witkovsky, P., Rice, M.E. (2013) TRPM2 channels are required for NMDA-induced burst firing and contribute to H2O2-dependent modulation in substantia nigra pars reticulata GABAergic neurons. J. Neurosci. 33: 1157-1168.

Patel, J.C., Rossignol, E., *Rice, M.E., *Machold, R.P. (2012) Opposing regulation of dopaminergic activity and exploratory motor behavior by forebrain and brainstem cholinergic circuits. Nature Commun. 3: 1172;  doi: 10.1038/ncomms2144 (*co-corresponding authors).

Patel, J.C., Rice, M.E. (2012) Classification of H2O2 as a neuromodulator that regulates striatal dopamine release on a subsecond time scale. ACS Chem. Neurosci. 3: 991-1001.

Rice, M.E. (2012) Brain ascorbate: protective, yet permissive for redox signaling. In: Neural Metabolism In Vivo; Advances in Neurobiology; Advances in Neurobiology 4, Choi, I.-Y. and Gruetter, R. eds. New York: Springer. 1051-1073.

Pan, Y., Chau, L., Liu, S., Avshalumov, M.V., Rice, M.E., Carr, K.D. (2011) A food restriction protocol that increases drug reward decreases TrkB in the ventral tegmental area, with no effect on BDNF or TrkB protein levels in dopaminergic forebrain regions. Neuroscience. 197: 330-338.

Patel, J.C., Witkovsky, P., Coetzee, W.A., Rice, M.E. (2011) Subsecond regulation of striatal dopamine release by presynaptic KATP channels. J. Neurochem. 118: 721-736.

Rice, M.E., Patel, J.C., Cragg, S.J. (2011) Dopamine release in the basal ganglia. Neuroscience. 198: 112-137.

Rice, M.E. (2011) H2O2: a dynamic neuromodulator. The Neuroscientist. 17: 389-406.

Stouffer, M.A., Ali, S., Reith, M.E.A., Sarti, F., Patel, J.C., Carr, K.D., Rice, M.E. (2011) SKF-83566, a D1 dopamine receptor antagonist, inhibits the dopamine transporter. J. Neurochem. 118: 714-720.

Chen, B.T., Patel, J.C., Moran, K.A., Rice, M.E. (2011) Differential calcium dependence of axonal versus somatodendritic dopamine release, with characteristics of both in the ventral tegmental area. Front. Syst. Neurosci. 5: 39.

Lee, C.R., Witkovsky, P., Rice, M.E. (2011) Regulation of substantia nigra pars reticulata GABAergic neuron activity by H2O2 via flufenamic acid-sensitive channels and K-ATP channels. Front. Syst. Neurosci. 5: 14.

*Bao, L., *Patel, J.C., Walker, R.H., Shashidharan, P., Rice, M.E. (2010) Dysregulation of striatal dopamine release in a mouse model of dystonia. J. Neurochem. 114: 1781-1791. (*co-first authors)

*Page, M.E., *Bao, L., Andre, P., Pelta-Heller, J., Sluzas, E., Gonzalez-Alegre, P., Iacovitti, L., Rice, M.E., Ehrlich, M.E. (2010) Cell-autonomous alteration of dopaminergic transmission by wild type and mutant (ΔE) TorsinA in transgenic mice. Neurobiol. Dis. 39: 318-326. (*co-first authors)

Tecuapetla, F., Patel, J.C., Xenias, H., English, D., Tadros, I., Shah, F., Deisseroth, K., Rice, M.E., Tepper, J.M., Koós, T. (2010) Glutamatergic signaling by mesolimbic dopamine neurons in the nucleus accumbens. J. Neurosci. 30: 7105-7110.

Li, X., Patel, J.C., Wang, J., Avshalumov, M.V., Nicholson, C., Buxbaum, J.D., Elder, G.A., Rice, M.E., Yue, Z. (2010) Enhanced motor performance and striatal dopamine transmission caused by LRRK2 overexpression in mice is eliminated by familial Parkinson’s Disease mutation G2019S. J. Neurosci. 30: 1788-1797.

Witkovsky, P., Patel, J.C., Lee, C.R., Rice, M.E. (2009) Immunocytochemical identification of proteins involved in dopamine release from the somatodendritic compartment of nigral dopaminergic neurons. Neuroscience. 164: 488-496.