Biomaterial Database

Influence of the dorsal and median raphe nuclei on neurons in the periaqueductal gray matter: role of 5-hydroxytryptamine. 1994

T A Lovick

Department of Physiology, University of Birmingham, U.K.

In rats anaesthetized with urethane, selective activation of neuronal perikarya in the dorsal raphe nucleus evoked inhibitory (n = 17) and excitatory (n = 10) responses in single neurons recorded in the dorsolateral and lateral sectors of the periaqueductal gray matter and in the adjacent tegmental area. A further 11 cells showed biphasic inhibitory/excitatory responses. Ongoing activity of > 85% of the cells was inhibited by iontophoretic application of 5-hydroxytryptamine (1-70 nA). The duration of the inhibitory response evoked from the dorsal raphe nucleus was increased by 66-75% during iontophoretic application (3-10 nA) of the 5-hydroxytryptamine (serotonin) reuptake blocker paroxetine (five of six cells). In contrast, excitatory responses evoked from the dorsal raphe nucleus were either reduced (n = 3) or replaced by inhibitory responses (n = 2) in the presence of paroxetine. Paroxetine also produced a reduction in baseline firing and potentiated the responses of neurons to iontophoretically applied 5-hydroxytryptamine. Stimulation in the median raphe nucleus did not produce any significant changes in the activity of five neurons tested in the periaqueductal gray matter. It is suggested that the inhibitory influence of the dorsal raphe nucleus on cells in the dorsal half of the periaqueductal gray matter is mediated by 5-hydroxytryptamine. This projection may be involved in modulating the level of excitability of neurons in the midbrain aversive system which integrate defence behaviour. In addition, there appears to be a non-serotonergic excitatory projection from the dorsal raphe nucleus to the periaqueductal gray matter. The functional role of this projection remains obscure.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008845	Microinjections	The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.	Microinjection
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D010487	Periaqueductal Gray	Central gray matter surrounding the CEREBRAL AQUEDUCT in the MESENCEPHALON. Physiologically it is probably involved in RAGE reactions, the LORDOSIS REFLEX; FEEDING responses, bladder tonus, and pain.	Mesencephalic Central Gray,Midbrain Central Gray,Central Gray Substance of Midbrain,Central Periaqueductal Gray,Griseum Centrale,Griseum Centrale Mesencephali,Periaqueductal Gray Matter,Substantia Grisea Centralis,Substantia Grisea Centralis Mesencephali,Central Gray, Mesencephalic,Central Gray, Midbrain,Gray Matter, Periaqueductal,Gray, Central Periaqueductal,Griseum Centrale Mesencephalus,Periaqueductal Grays, Central
D011903	Raphe Nuclei	Collections of small neurons centrally scattered among many fibers from the level of the TROCHLEAR NUCLEUS in the midbrain to the hypoglossal area in the MEDULLA OBLONGATA.	Caudal Linear Nucleus of the Raphe,Interfascicular Nucleus,Nucleus Incertus,Rostral Linear Nucleus of Raphe,Rostral Linear Nucleus of the Raphe,Superior Central Nucleus,Central Nucleus, Superior,Incertus, Nucleus,Nuclei, Raphe,Nucleus, Interfascicular,Nucleus, Raphe,Nucleus, Superior Central,Raphe Nucleus
D001931	Brain Mapping	Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.	Brain Electrical Activity Mapping,Functional Cerebral Localization,Topographic Brain Mapping,Brain Mapping, Topographic,Functional Cerebral Localizations,Mapping, Brain,Mapping, Topographic Brain
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D004924	Escape Reaction	Innate response elicited by sensory stimuli associated with a threatening situation, or actual confrontation with an enemy.	Flight Reaction,Escape Reactions,Flight Reactions,Reaction, Escape,Reaction, Flight,Reactions, Escape,Reactions, Flight
D006710	Homocysteine	A thiol-containing amino acid formed by a demethylation of METHIONINE.	2-amino-4-mercaptobutyric acid,Homocysteine, L-Isomer,2 amino 4 mercaptobutyric acid,Homocysteine, L Isomer,L-Isomer Homocysteine
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential