Although the importance of the nucleus raphe magnus in descending inhibitory control of nociception is clear, it is not known whether these effects are equivalent for different types of nociception. Thus, we examined the differential inhibition of behavioral responses evoked by A or C fiber thermonociceptor activation by electrical stimulation of nucleus raphe magnus neurons as well as the invo...

We have studied the distribution of neurokinin A-like immunoreactive cell bodies and fibers in the cat brainstem. The densest clusters of perikarya containing the peptide were observed in the periaqueductal gray, inferior colliculus, postpyramidal nucleus of the raphe, medial nucleus of the solitary tract and in the lateral reticular nucleus. By contrast, the interpeduncular nucleus, magnocellu...

The role of raphe nucleus (R.N) and serotonin in some behaviors such as sleep, cognition, mood, and memory has previously been reported. The median raphe (MR) nucleus is a major serotonin-containing cell group within the brainstem and is one of the main sources of projections to the septum and hippocampus. The hippocampus is widely believed to be essential for context-conditioning learning. Mor...

Midbrain periaqueductal gray mater area (PAG) receives some afferents from anterolateral system, frontal cortex, and hypothalamus that inhibit pain through its descending pathway that synapses medial raphe nuclus (mrph) and finally terminates on spinal cord enkephalinergic interneurons in layers II and III. In the present study, the role of Ca+2–channels located on medial raphe nucleus neurons ...

The present studies sought to investigate the effect of tryptophan alone or coadministration of tryptophan and ethanol on the interaction of central frontal cortex and dorsal raphe nucleus serotonergic functional activities by utilizing in vivo microdialysis. Tryptophan (50 mg/kg, i.p.) led to a significant increase in the levels of 5-HIAA, a metabolite of serotonin (5-HT), in the dorsal raphe ...

Midbrain periaqueductal gray mater area (PAG) receives some afferents from anterolateral system, frontal cortex, and hypothalamus that inhibit pain through its descending pathway that synapses medial raphe nuclus (mrph) and finally terminates on spinal cord enkephalinergic interneurons in layers II and III. In the present study, the role of Ca+2–channels located on medial raphe nucleus neurons ...

INTRODUCTION Post-traumatic stress disorder (PTSD) is an anxiety disorder that develops after exposure to a life-threatening traumatic experience. Meta-analyses of the brainstem showed that midsagittal area of the pons was significantly reduced in patients with PTSD, suggesting a potential apoptosis in dorsal raphe nucleus after single-prolonged stress (SPS). The aim of this study is to investi...

BACKGROUND AND PURPOSE Tryptophan hydroxylase activity was assayed in cell-free extracts of rat brain base arteries as marker of a serotonergic innervation. METHODS Estimation of the enzymatic activity was made in untreated male Sprague-Dawley rats (n = 53) and in those who underwent destruction of the dorsal and median raphe nuclei (n = 10). RESULTS Tryptophan hydroxylase activity was meas...

The recent introduction ofa number offluorescent retrograde axonal tracers that have different emission spectra (1,2,9,10,25,26) has permitted the investigation of possible collateral projections of senotonengic neurons. Extensive collateralization from single neurons in the raphe nuclei was expected given the widespread distribution ofserotonergic nerve terminals in the central nervous system ...

Theta rhythm in many brain structures characterizes wakefulness and desynchronized sleep in most subprimate mammalian brains. In close relation to behaviors, theta frequency and voltage undergo a fine modulation which may involve mobilization of dorsal raphe nucleus efferent pathways. In the present study we analyzed frequency modulation (through instantaneous frequency variation) of theta wave...