American journal of physiology. Regulatory, integrative and comparative physiology
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Sep 2001
The influence of topical capsaicin on the local thermal control of skin blood flow in humans.
To test whether heat-sensitive receptors participate in the cutaneous vascular responses to direct heating, we monitored skin blood flow (SkBF; laser Doppler flowmetry) where the sensation of heat was induced either by local warming (T(Loc); Peltier cooling/heating unit) or by both direct warming and chemical stimulation of heat-sensitive nociceptors (capsaicin). In part I, topical capsaicin (0.075 or 0.025%) was applied to 12 cm(2) of skin 1 h before stepwise local warming of untreated and capsaicin-treated forearm skin. Pretreatment with 0.075% capsaicin cream shifted the SkBF/T(Loc) relationship to lower temperatures by an average of 6 +/- 0.8 degrees C (P < 0.05). ⋯ Cutaneous vasomotor responses were compared when the temperatures at these two sites were perceived to be the same. SkBF differed significantly between capsaicin and control sites when compared on the basis of actual temperatures, but that difference became insignificant when compared on the basis of the perceived temperatures. These data suggest heat-sensitive nociceptors are important in the cutaneous vasodilator response to local skin warming.
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Sep 2001
Differential roles for glutamate receptor subtypes within commissural NTS in cardiac-sympathetic reflex.
Ischemic stimulation of cardiac receptors evokes excitatory sympathetic reflexes. Although the nucleus of the solitary tract (NTS) is an important site for integration of visceral afferents, its involvement in the cardiac-renal sympathetic reflex remains to be fully defined. This study examined the role of glutamate receptor subtypes in the commissural NTS in the sympathetic responses to stimulation of cardiac receptors. ⋯ Bilateral microinjection of 10 pmol of 6-cyano-7-nitroquinoxaline-2,3-dione, a non-N-methyl-D-aspartate (NMDA) antagonist, into the commissural NTS eliminated the pressor and RSNA responses to BK application in 10 rats. However, microinjection of 2-amino-5-phosphonopentanoic acid (0.1 and 1 nmol, n = 8), an NMDA- receptor antagonist, or alpha-methyl-4-carboxyphenylglycine (0.1 and 1 nmol, n = 5), a glutamate metabotropic receptor antagonist, failed to attenuate significantly the pressor and RSNA responses to stimulation of cardiac receptors with BK. Thus this study suggests that non-NMDA, but not NMDA and glutamate metabotropic, receptors in the commissural NTS play an important role in the sympathoexcitatory reflex response to activation of cardiac receptors during myocardial ischemia.
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Am. J. Physiol. Regul. Integr. Comp. Physiol. · Sep 2001
Restraint increases prolactin and REM sleep in C57BL/6J mice but not in BALB/cJ mice.
Sleep is generally considered to be a recovery from prior wakefulness. The architecture of sleep not only depends on the duration of wakefulness but also on its quality in terms of specific experiences. In the present experiment, we studied the effects of restraint stress on sleep architecture and sleep electroencephalography (EEG) in different strains of mice (C57BL/6J and BALB/cJ). ⋯ Furthermore, this study confirms that different stressors differentially affect NREM and REM sleep. Whereas restraint stress promotes REM sleep in C57BL/6J mice, we previously found that in the same strain, social defeat stress promotes NREM sleep. As such, studying the consequences of specific stressful stimuli may be an important tool to unravel both the mechanism and function of different sleep stages.