American journal of physiology. Regulatory, integrative and comparative physiology
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Jun 2005
Cytokine profiles in the testes of rats treated with lipopolysaccharide reveal localized suppression of inflammatory responses.
Evidence indicates that the testis possesses a reduced capacity to mount inflammatory and rejection responses, which undoubtedly contributes to the ongoing survival of the highly immunogenic germ cells. The contribution of local cytokine expression to this condition was investigated in adult male rats treated with lipopolysaccharide to induce inflammation. Cytokine mRNA and protein expression were determined in tissue extracts and fluids by Northern blot analysis, quantitative PCR, or RNAse protection assay and specific ELISAs. ⋯ These data indicate that inflammatory and regulatory cytokine activity is regulated at both transcriptional and posttranslational levels in a testis-specific manner. It is concluded that a novel pattern of suppression of proinflammatory cytokine responses and normal or elevated expression of immunoregulatory cytokines may be responsible for reduced inflammatory responses and enhanced graft survival in the testis. These data have important implications for the understanding and treatment of male autoimmune infertility, testicular inflammation. and carcinogenesis.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · May 2005
Effects of menstrual cycle and physical training on heat loss responses during dynamic exercise at moderate intensity in a temperate environment.
We evaluated the effects of the menstrual cycle and physical training on heat loss (sweating and cutaneous vasodilation) responses during moderate exercise in a temperate environment. Ten untrained (group U) and seven endurance-trained (group T) women (maximal O2 uptake of 36.7+/-1.1 vs. 49.4+/-1.7 ml.kg-1.min-1, respectively; P<0.05) performed a cycling exercise at 50% maximal O2 uptake for 30 min during both the midfollicular and midluteal menstrual phase in a temperate environment (ambient temperature of 25 degrees C, relative humidity of 45%). In group U, plasma levels of estrone, estradiol, and progesterone at rest and esophageal temperature (Tes) during exercise were significantly higher during the midluteal than during the midfollicular phase (P<0.05). ⋯ These results suggest that heat loss responses in group U were inhibited in the midluteal phase compared with in the midfollicular phase. Menstrual cycle had no remarkable effects in group T. Physical training improved heat loss responses, which was more marked in the midluteal than in the midfollicular phase.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · May 2005
Cutaneous vasoconstrictor responses to norepinephrine are attenuated in older humans.
Cutaneous vasoconstriction (VC) in response to cooling is impaired with human aging. On the basis of previous findings that older humans rely predominantly on norepinephrine (NE) for reflex VC of skin blood vessels, and that the VC effects of NE are blunted with age in many vascular beds, we tested the hypothesis that cutaneous VC responses to exogenous NE are attenuated in aged skin compared with young skin. In 11 young (18-30 yr) and 11 older (62-76 yr) men and women, skin blood flow was monitored at two forearm sites with laser Doppler (LD) flowmetry, while local skin temperature was clamped at 34 degrees C. ⋯ Older maximal VC responses were also blunted compared with young [-80 (confidence interval:-73,-87) vs.-88 (confidence interval:-87, -90) %DeltaCVCbase, P=0.03]. NE-mediated cutaneous VC is blunted at both physiological and superphysiological doses in older subjects compared with young subjects. Considering that NE is the only functional neurotransmitter mediating reflex VC in aged skin, attenuated NE-mediated VC may further predispose older humans to excess heat loss in the cold.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Apr 2005
Subfornical organ disconnection alters Fos expression in the lamina terminalis, supraoptic nucleus, and area postrema after intragastric hypertonic NaCl.
The lamina terminalis was severed by a horizontal knife cut through the anterior commissure to determine the effects of a disconnection of the subfornical organ (SFO) on drinking and Fos-like immunoreactivity (Fos-ir) in the rat brain in response to an intragastric load of hypertonic saline (5 ml/kg of 1.5 M NaCl by gavage). After an initial load, knife-cut rats drank significantly less water than sham-cut rats, thus confirming a role for the SFO in osmotic drinking. After a second load at least 1 wk later, the rats were not allowed to drink after the gavage and were perfused for analysis of Fos-ir at 90 min. ⋯ Fos-ir was expressed mainly in the midcoronal and caudal parts of the area postrema of sham-cut rats, and this expression was greatly reduced in knife-cut rats. These findings strengthen the case for the presence of independently functioning osmoreceptors within the SFO and suggest that the structures of the lamina terminalis provide mutual inhibition during hypernatremia. They also demonstrate that the Fos-ir in the area postrema after intragastric osmotic loading is heavily dependent on the intact connectivity of the SFO.
-
Am. J. Physiol. Regul. Integr. Comp. Physiol. · Oct 2004
Medullary substrate and differential cardiovascular responses during stimulation of specific acupoints.
Electroacupuncture (EA) at P5-P6 acupoints overlying the median nerve reduces premotor sympathetic cardiovascular neuronal activity in the rostral ventral lateral medulla (rVLM) and visceral reflex pressor responses. In previous studies, we have noted different durations of influence of EA comparing P5-P6 and S36-S37 acupoints, suggesting that point specificity may exist. The purpose of this study was to evaluate the influence of stimulating P5-P6 (overlying the median nerve), LI4-L7 (overlying branches of the median nerve and the superficial radial nerve), LI6-LI7 (overlying the superficial radial nerve), LI10-LI11 (overlying the deep radial nerves), S36-S37 (overlying the deep peroneal nerves), or K1-B67 (overlying terminal branches of the tibial nerves) specific acupoints, overlying deep and superficial somatic nerves, on the excitatory cardiovascular reflex and rVLM responses evoked by stimulation of chemosensitive receptors in the cat's gallbladder with bradykinin (BK) or direct splanchnic nerve (SN) stimulation. ⋯ In addition, EA stimulation at P5-P6 and LI4-L7 decreased rVLM neuronal activity by 41 and 12%, respectively, for >1 h, demonstrating that prolonged input into the medulla during stimulation of somatic nerves, depending on the degree of convergence, leads to more or less inhibition of activity of these cardiovascular neurons. Thus EA at acupoints overlying deep and superficial somatic nerves leads to point-specific effects on cardiovascular reflex responses. In a similar manner, sympathetic cardiovascular rVLM neurons that respond to both visceral (reflex) and somatic (EA) nerve stimulation manifest graded responses during stimulation of specific acupoints, suggesting that this medullary region plays a role in site-specific inhibition of cardiovascular reflex responses by acupuncture.