Do silent dopaminergic neurons exist in rat substantia nigra in vivo?

Dai, Mi; Tepper, James M.

doi:10.1016/s0306-4522(97)00615-5

Cited by 36 publications

(20 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In accordance with the generally accepted view (Bunney and Grace 1978; for additional references, see Dai and Tepper 1998), we have interpreted the present changes in the number of DA neurons per track as reflecting those in the number of neurons spontaneously generating action potentials (i.e., some neurons are normally silent). On the other hand, Dai and Tepper (1998) have recently suggested that virtually all SNC DA neurons (Ͼ98%) are spontaneously active, even in anesthetized animals.…”

Section: Changes Following Intermittent Cocaine Injectionssupporting

confidence: 84%

“…On the other hand, Dai and Tepper (1998) have recently suggested that virtually all SNC DA neurons (Ͼ98%) are spontaneously active, even in anesthetized animals. According to these investigators, changes in the number of active neurons per track following D 2 blockade are secondary to such factors as increased firing rates or decreased electrotonic lengths of recorded neurons, which would spuriously increase the likelihood of finding slow-firing neurons or those that are distant from the recording electrode.…”

Section: Changes Following Intermittent Cocaine Injectionsmentioning

confidence: 99%

“…Moreover, acute D 2 antagonism by sulpiride (Gao et al 1998) or 5-day D 2 stimulation can specifically reverse these changes. Direct antidromic stimulation of DA neurons during 9-track population sampling (Dai and Tepper 1998) from cocaine-pretreated animals might provide a further clarification.…”

Section: Changes Following Intermittent Cocaine Injectionsmentioning

confidence: 99%

See 2 more Smart Citations

Altered Activity of Midbrain Dopamine Neurons Following 7-Day Withdrawal from Chronic Cocaine Abuse is Normalized by D2 Receptor Stimulation During the Early Withdrawal Phase

Lee

Gao

Davidson

et al. 1999

Neuropsychopharmacology

View full text Add to dashboard Cite

Using in vivo single-unit recording in rats, we compared the effects of continuous cocaine infusion via minipump or single daily injections (both 40 mg/kg/d ϫ 14 days, SC) on the activity of putative dopamine (DA) neurons in the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA).The two opposite behavioral outcomes in animal models of chronic cocaine or amphetamine abuse are sensitization and tolerance, which are induced by intermittent injection or continuous infusion, respectively (Inada et al. 1992;King et al. 1992;Lau et al. 1991;Post and Rose 1976;Reith et al. 1987). Behavioral sensitization has been hypothesized as a model of the increasing reinforcing effects of cocaine in humans, especially during the early stages of abuse (Kilbey and Ellinwood 1977;Post and Contel 1983;Robinson and Berridge 1993;Mendrek et al. 1998;Kalivas 1995). Tolerance, on the other hand, may provide an animal model for elucidating time-dependent loss of mental and physical energy associated with stimulant withdrawal after multi-day high-dose, compulsive binges (Gawin and Ellinwood 1988;Weiss et al. 1995).The two dosing regimens for the above stimulants are also associated with distinctive electrophysiological changes in the potency of dopamine (DA) agonists in inhibiting activity of DA neurons in the substantia nigra zona compacta (SNC, which projects primarily to the dorsal striatum) and ventral tegmental area (VTA, which projects to the ventral striatum and prefrontal cortex). In the SNC, for example, while both continuous (Kamata and Rebec 1984;Ellinwood and Lee 1983;Lee and Ellinwood 1989), the mechanisms underlying this subsensitivity are different (Pitts et al. 1989(Pitts et al. , 1993Lee et al. 1997). For intermittent injections (which lead to phasically high levels of cocaine) an enabling by a D 1 -dependent mechanism appears to play a key role in the agonist subsensitivity (Pitts et al. 1989(Pitts et al. , 1993Lee et al. 1997), whereas a direct change in D 2 autoreceptor sensitivity might underlie the subsensitivity following continuous infusion (Lee et al. 1997). In contrast to the SNC, the findings in the VTA are most consistent with autoreceptor subsensitivity (Henry et al. 1989;Lee et al. 1997;White et al. 1995) and normosensitivity (Lee et al. 1997) 1 day after withdrawal from intermittent and continuous regimens, respectively. The differential effects of chronic cocaine treatments on the VTA and SNC may be reflective of their different afferent connections as well as differences in their respective DA receptor populations.Following a longer withdrawal period (e.g., 7 days), intermittent injections are generally associated with normosensitivity of the SNC and VTA DA neurons to DA agonists (Henry et al. 1989;White et al. 1995;Lee et al. 1997). Continuous infusion is also associated with a normosensitivity of the VTA DA neurons following 7-day withdrawal. However, as we have demonstrated previously, the SNC DA neurons become supersensitive to apomorphine (Ellinwood and Lee 1983;Lee and Ellinwood 1989...

show abstract

Section: Changes Following Intermittent Cocaine Injectionssupporting

confidence: 84%

Section: Changes Following Intermittent Cocaine Injectionsmentioning

confidence: 99%

See 1 more Smart Citation

Altered Activity of Midbrain Dopamine Neurons Following 7-Day Withdrawal from Chronic Cocaine Abuse is Normalized by D2 Receptor Stimulation During the Early Withdrawal Phase

Lee

Gao

Davidson

et al. 1999

Neuropsychopharmacology

View full text Add to dashboard Cite

show abstract

“…While drug-induced changes in the number of cells per track might well indicate changes in the proportion of spontaneously active neurons, alternative explanations have been proposed including changes in firing rate and/or changes in the extent to which the action potential invades the dendrites thereby altering the size of the extracellular field potential of the neuron. Both of these would alter the probability of encountering a neuron while lowering a microelectrode through a designated region of the brain (see discussions in Diana et al 1995a andDai andTepper 1998). For example, a reduction in the number of dopaminergic cells per track was observed after chronic ethanol administration and subsequent withdrawal and attributed to a reduced number of spontaneously active neurons due to depolarization block (Shen and Chiodo 1993).…”

Section: Effects Of Chronic Antipsychotic Drug Administrationthe mentioning

confidence: 99%

Electrophysiological Pharmacology of Mesencephalic Dopaminergic Neurons

Diana¹,

Tepper²

2002

Dopamine in the CNS II

View full text Add to dashboard Cite

“…Almost all nigrostriatal dopaminergic neurons fire spontaneously in vivo (Tepper et al, 1984;Dai and Tepper, 1998; but see Chiodo, 1988;Floresco et al, 2003) at relatively slow rates averaging between 4 and 5 spikes/s (Bunney et al, 1973;Deniau et al, 1978;Guyenet and Aghajanian, 1978;Bunney, 1979;Grace and Bunney, 1983). The spontaneous activity exists along a continuum of firing patterns that is only loosely related to the mean rate Freeman et al, 1985;Hyland et al, 2002).…”

Section: Introductionmentioning

confidence: 99%