A GABA cardiovascular mechanism in the dorsal raphe of the rat

Robinson, Susan E.; Rice, M. Andrea; Davidson, W. Sean

doi:10.1016/0028-3908(86)90213-3

Cited by 11 publications

(5 citation statements)

References 22 publications

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“…In contrast, stimulation of the ventrolateral column of the PAG (PAGvl) produces hypoactivity, hypotension, bradycardia, and an opioid dependent antinociception. The dorsal raphe nucleus (DR) embedded in the caudal portion of the PAGvl has also been implicated in antinociception and cardiovascular regulation (Robinson et al, 1986; Connor and Higgins, 1990; Lovick, 1993; Wang and Nakai, 1994) and is believed to play an important role in regulating neural activity in the PAG (Lovick, 1993).…”

mentioning

confidence: 99%

GABAergic projection from the ventral tegmental area and substantia nigra to the periaqueductal gray region and the dorsal raphe nucleus

Kirouac

Mabrouk

2003

J of Comparative Neurology

111

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Previous studies have shown that neurons in the ventral tegmental area (VTA) and substantia nigra (SN) project to the ventrolateral periaqueductal gray (PAGvl) and dorsal raphe nucleus (DR). Research has also shown that stimulation of neurons in the VTA/SN elicits cardiovascular depressor responses that are mediated by a projection to the PAGvl/DR. Anatomic and physiological experiments were done in the present study to determine the neurochemical identity of the VTA/SN projection to the PAGvl/DR. Experiments were done to characterize the origin and chemical nature of this projection by combining cholera toxin B tracing with immunofluorescence for the 67K isoform of glutamic acid decarboxylase (GAD) and tyrosine hydroxylase. The PAGvl/DR region was found to receive a substantial input from neurons in the VTA, SN, and deep mesencephalic nucleus. The DR was preferentially innervated by neurons in the VTA, whereas the PAGvl was preferentially innervated by neurons in the SN. A proportion of neurons in the VTA and the reticular portion of the SN found to project to the PAGvl/DR were GAD positive. In addition, experiments were done in urethane-anesthetized rats to determine whether injections of a gamma-aminobutyric acid (GABA) antagonist in the region of the PAGvl/DR attenuated the cardiovascular depressor responses produced by glutamate stimulation of the VTA/SN. Injections of the GABA-blocking agent picrotoxin (2.5 nmol, 500 nl) into the PAGvl/DR eliminated the cardiovascular responses from stimulation of the VTA/SN (0.01 M, 50 nl). The results of the present investigation provide evidence for a GABAergic projection from the VTA/SN to the PAGvl/DR. This projection may be an important regulator of the PAGvl/DR, an area of the midbrain involved in the production of behavioral and physiological responses to pain and stress.

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confidence: 99%

GABAergic projection from the ventral tegmental area and substantia nigra to the periaqueductal gray region and the dorsal raphe nucleus

Kirouac

Mabrouk

2003

J of Comparative Neurology

111

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“…Studies using mostly extensive electrical stimulation have suggested the participation of these areas in cardiovascular control (17)(18)(19)24). These studies showed that electrical stimulation of the DRN and MRN induces mainly pressor responses in the rat, and that these responses are mediated by 5-HT.…”

Section: Discussionmentioning

confidence: 99%

“…Tracing studies revealed the existence of a reciprocal pathway between the DRN and MRN, which is at least partially serotonergic (16,(21)(22)(23). Electrical or chemical stimulation of either nucleus elicits similar cardiovascular and behavioral responses (17)(18)(19)24). For instance, electrical stimulation of DRN or MRN elicits pressor responses in the anesthetized rat, that seem to require the participation of the rostral ventrolateral medulla (RVLM), considered a major component of the formerly called "vasomotor center" of the brainstem (25,26).…”

Section: Introductionmentioning

confidence: 99%

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Functional mapping of the cardiorespiratory effects of dorsal and median raphe nuclei in the rat

Alvarenga

Pires

Neto

2005

Braz J Med Biol Res

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The dorsal (DRN) and median (MRN) raphe nuclei are important sources of serotonergic innervation to the forebrain, projecting to sites involved in cardiovascular regulation. These nuclei have been mapped using electrical stimulation, which has the limitation of stimulating fibers of passage. The present study maps these areas with chemical stimulation, investigating their influence on cardiorespiratory parameters. Urethane-anesthetized (1.2 g/kg, iv) male Wistar rats (280-300 g) were instrumented for pulsatile and mean blood pressure (MBP), heart rate, renal nerve activity, and respiratory frequency recordings. Microinjections of L-glutamate (0.18 M, 50-100 nl with 1% Pontamine Sky Blue) were performed within the DRN or the MRN with glass micropipettes. At the end of the experiments the sites of microinjection were identified. The majority of sites within the MRN (86.1%) and DRN (85.4%) evoked pressor responses when stimulated (DRN: ∆MBP = +14.7 ± 1.2; MRN: ∆MBP = +13.6 ± 1.3 mmHg). The changes in renal nerve activity and respiratory rate caused by Lglutamate were +45 ± 11 and +42 ± 9% (DRN; P < 0.05%), +40 ± 10 and +29 ± 7% (MRN, P < 0.05), respectively. No significant changes were observed in saline-microinjected animals. This study shows that: a) the blood pressure increases previously observed by electrical stimulation within the raphe are due to activation of local neurons, b) this pressor effect is due to sympathoexcitation because the stimulation increased renal sympathetic activity but did not produce tachycardia, and c) the stimulation of cell bodies in these nuclei also increases the respiratory rate.

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“…[96] Studies have shown that the DRN modulates physiological arousal via its projections to central autonomic control systems [97,98] ; and that pharmacological manipulations of the DRN affect autonomic activities, including blood pressure and heart rate, in anesthetized rats. [99] Pupil diameter is another index of the central arousal state, [100] and optogenetic activation of 5-HT neurons in the DRN increases the pupil size of awake male mice depending on the level of environmental uncertainty. [101] Calcium imaging studies have shown that DRN 5-HT neurons are activated by several conditions, such as electric foot shocks, elevated plus-maze open-arm exploration, first social interaction with a novel male mouse, and both sucrose and quinine consumption.…”

Section: The Drn and Other Traits That Could Affect Aggressive Behavi...mentioning

confidence: 99%

Aggression modulator: Understanding the multifaceted role of the dorsal raphe nucleus

Mitsui,

Takahashi

2024

BioEssays

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Aggressive behavior is instinctively driven behavior that helps animals to survive and reproduce and is closely related to multiple behavioral and physiological processes. The dorsal raphe nucleus (DRN) is an evolutionarily conserved midbrain structure that regulates aggressive behavior by integrating diverse brain inputs. The DRN consists predominantly of serotonergic (5‐HT:5‐hydroxytryptamine) neurons and decreased 5‐HT activity was classically thought to increase aggression. However, recent studies challenge this 5‐HT deficiency model, revealing a more complex role for the DRN 5‐HT system in aggression. Furthermore, emerging evidence has shown that non‐5‐HT populations in the DRN and specific neural circuits contribute to the escalation of aggressive behavior. This review argues that the DRN serves as a multifaceted modulator of aggression, acting not only via 5‐HT but also via other neurotransmitters and neural pathways, as well as different subsets of 5‐HT neurons. In addition, we discuss the contribution of DRN neurons in the behavioral and physiological aspects implicated in aggressive behavior, such as arousal, reward, and impulsivity, to further our understanding of DRN‐mediated aggression modulation.

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A GABA cardiovascular mechanism in the dorsal raphe of the rat

Cited by 11 publications

References 22 publications

GABAergic projection from the ventral tegmental area and substantia nigra to the periaqueductal gray region and the dorsal raphe nucleus

GABAergic projection from the ventral tegmental area and substantia nigra to the periaqueductal gray region and the dorsal raphe nucleus

Functional mapping of the cardiorespiratory effects of dorsal and median raphe nuclei in the rat

Aggression modulator: Understanding the multifaceted role of the dorsal raphe nucleus

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