with the property that for any pair r, s of elements of R either r = s or there is very little free cancellation in forming the product rs. The classical example of such a group is the fundamental group of a closed orientable 2-manifold of genus k. The study of this group has given rise both to the theory of one-relator groups, initiated by Magnus ([3]), and to the theory of small cancellation ...

The present study demonstrated that 5-HT receptor mRNA was expressed with moderate level in the NRM neurons. Most of 5-HT 1A 1A receptor mRNA positive cells were 5-HT neurons, suggesting the majority of 5-HT receptor in the NRM might be autoreceptors. Eight 1A hours after carrageenan inflammation, the expression of 5-HT receptor mRNA in the NRM neurons, especially in the 5-HT neurons, 1A was si...

Suppression of reactions to one noxious stimulus by a spatially distant noxious stimulus is termed heterotopic antinociception. In lightly anesthetized rats, a noxious visceral stimulus, colorectal distension (CRD), suppressed motor withdrawals but not blood pressure or heart rate changes evoked by noxious hindpaw heat. Microinjection of muscimol, a GABA(A) receptor agonist, into raphe magnus (...

There is evidence that serotonin [5-hydroxytryptamine (5-HT)] is involved in the physiological responses to hypercapnia. Serotonergic neurons represent the major cell type (comprising 15-20% of the neurons) in raphe magnus nucleus (RMg), which is a medullary raphe nucleus. In the present study, we tested the hypothesis 1) that RMg plays a role in the ventilatory and thermal responses to hyperca...

Previous studies have identified two neurectoderm-specific serotonin binding proteins (SBP), one with an apparent Mr of 45 kDa, and one of 56 kDa. The current experiments were undertaken to test the hypothesis that these proteins are specific components of serotonergic neurons. Since actin has been found to bind serotonin, the relationship of the 2 forms of SBP to actin was also investigated. A...

It has been shown previously that the muscarinic cholinergic system in the nucleus raphe magnus (NRM) is involved in the modulation of nociception. In this study, we examined the direct actions of muscarine on the NRM neurons in a slice preparation. Muscarine (1-30 microM) produced a dose-dependent hyperpolarization in a subpopulation of the NRM cells that contain 5-hydroxytryptamine (5-HT). In...

Experiments were done in alpha-chloralose-anesthetized rats to determine a pathway mediating the cardiovascular depressor responses elicited from stimulation of the ventral tegmental area (VTA). The magnitude of the depressor responses elicited by glutamate stimulation (0.1 M/30 nl) of the VTA was examined after neuronal block produced by microinjections of lidocaine into ascending fiber bundle...

The midbrain periaqueductal gray (PAG) has been shown to be a site where various manipulations induce pain suppression. Recent physiological evidence (Behbehani and Pert, 1984; Behbehani et al., 1987) suggests that neurotensin has pronounced physiological actions in PAG and effects pain suppression. We have performed immunohistochemical studies in order to determine the magnitude and distributi...

A B S T R A C TIntroduction: The nucleus cuneiformis (NCF) and ventrolateral periaqueductal gray (vlPAG), two adjacent areas, mediate the central pain modulation and project to the nucleus raphe magnus (NRM). Methods: This study examined whether the antinociceptive effect of morphine microinjected into the NCF is influenced by inactivation of vlPAG and NRM in rats. Animals were bilaterally micr...