Lateral habenular influence on dorsal raphe neurons.
Previously, we have demonstrated that lateral habenula (LH) modulates the bioelectric activity of the hippocampus through the dorsal raphe nucleus functional involvement. In this study we have, preliminarily, electrophysiologically identified two types of raphe neurons: "slow" (S cells, serotonergic in nature); and "fast" (F cells, presumably GABAergic in nature). Then, we have shown that LH electrical stimulation at lower frequency induced an excitation of S and F neurons. LH stimulation at higher frequency inhibited only S neurons. Furthermore, iontophoretic NMDA excited S and F neurons. The excitatory effects of LH stimulation were antagonized by the iontophoretic 2-APV (NMDA antagonist). Iontophoretic GABA inhibited only S neurons. Iontophoretic bicuculline antagonized the LH-induced inhibition os S neurons. The data suggested a direct (NMDA-mediated) and indirect (through the F GABAergic inhibitory interneuron) influence of the LH on the serotonergic efferent neuron.
Ferraro
G
G
Institute of Human Physiology, University of Palermo, Italy.
Montalbano
M E
ME
Sardo
P
P
La Grutta
V
V
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D004594:Electrophysiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D019262:Habenula / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007478:Iontophoresis; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D011903:Raphe Nuclei / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D001640:Bicuculline