Simultaneous elevation of plasma insulin and catecholamines during endotoxicosis in the conscious and anesthetized rat

Divergent neuroendocrine responses to localized and systemic inflammation

The sympathetic nervous system (SNS) is part of an integrative network that functions to restore homeostasis following injury and infection. The SNS can provide negative feedback control over inflammation through the secretion of catecholamines from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Central autonomic structures receive information regarding the inflammatory status of the body and reflexively modulate SNS activity. However, inflammation and infection can also directly regulate SNS function by peripheral actions on postganglionic cells. The present review discusses how inflammation activates autonomic reflex pathways and compares the effect of localized and systemic inflammation on ACCs and postganglionic sympathetic neurons. Systemic inflammation significantly enhanced catecholamine secretion through an increase in Ca(2+) release from the endoplasmic reticulum. In contrast, acute and chronic GI inflammation reduced voltage-gated Ca(2+) current. Thus it appears that the mechanisms underlying the effects of peripheral and systemic inflammation neuroendocrine function converge on the modulation of intracellular Ca(2+) signaling.

Role of cytokines in testicular function

Inflammatory disease has been established to affect male reproductive function and fertility. Relevant inflammatory diseases include general and chronic infectious diseases as well as localized acute or chronic infections of the male genitourinary tract. Male accessory gland infections account for almost 15% of all cases of male infertility seen in infertility clinics while fertility usually is not a clinical objective among patients with acute systemic infections such as Gram-negative sepsis. Infections of the male accessory glands frequently are associated with increased counts of white blood cells in semen and elevated levels of proinflammatory cytokines in semen and the testis. There is a mounting body of evidence that demonstrates the importance of cytokines and chemokines in the regulation of testicular and glandular function during pathophysiological states as well as under normal physiological conditions when cytokines act as growth and differentiation factors. The purpose of this review is to examine the role of cytokines in the regulation of steroidogenesis and spermatogenesis in the testis under physiological and pathophysiological conditions and considers clinical investigations that help to improve the evaluation and treatment of male infertility.

Platelet-activating factor receptor antagonist attenuates endotoxin-induced vascular hyporeactivity in the pithed rat

The role of platelet activating factor (PAF) and nitric oxide (NO) in the endotoxin-induced hyporeactivity to noradrenaline was studied in the pithed rat. Pressor dose-response curves to noradrenaline (0.01-10 microg/kg, i.v.) were made starting 1 h after the administration of endotoxin (0.5 mg/kg, i.v.) to the rats. Saline was administered to the control rats. The PAF receptor antagonist, TCV-309 (3-bromo-5-[N-phenyl-N-[2-[[2-(1,2,3,4-tetrahydro-2-isoquinolylcarbon yloxy)ethyl]carbamoyl]ethy]carbamoyl]-1-propylpyridinium nitrate, 100 microg/kg, i.v.), or the NO synthase inhibitor, N(G)-monomethyl-L-arginine (L-NMMA, 30 mg/kg, i.v.), was administered to the endotoxin-treated rats 20 or 10 min before the noradrenaline challenge. L-NMMA reversed endotoxin-induced hyporeactivity completely. TCV-309 produced a significant, but partial attenuation of the hyporeactivity to noradrenaline (P < 0.01). There was still significant hyporeactivity when compared with the control rats (P < 0.01) and the L-NMMA-treated endotoxin-administered rats (P < 0.05). These data suggest that endogenous PAF contributes to the vascular hyporeactivity to noradrenaline induced by endotoxin and that NO plays a major role in the endotoxin-induced hyporeactivity.

Involvement of interleukin-1 in the inhibition of in vivo insulin release: possible role of adrenal glands

The effect of recombinant human interleukin-1 beta (rhIL-1b) on in vivo insulin secretion was examined in intact and adrenalectomized (ADX) rats under conscious and pentobarbital anesthetized conditions. In conscious rats, rhIL-1b dose-dependently decreased blood glucose levels at 2 h in both groups and significantly inhibited insulin release only at doses of 1 and 10 micrograms/kg in ADX rats. Under pentobarbital anesthesia, rhIL-1b administration decreased blood glucose levels 2 h later in both intact and ADX rats and resulted in severe hypoglycemia in ADX rats. At 2 h later, rhIL-1b significantly suppressed insulin release by pentobarbital injection in both intact and ADX rats. It is concluded that rhIL-1b suppresses in vivo insulin secretion in conscious ADX and anesthetized rats.

Endotoxin inhibition of glucocorticoid enzyme induction and in vivo 3H-dexamethasone labelling of rat liver nuclei

1. The effect of endotoxin on glucocorticoid (GC) induction of liver TO and TAT was investigated. 2. It was found that endotoxin inhibited not only TO GC induction, but also that of TAT, though to a lesser extent (17.41%). 3. Endotoxin did not influence the binding capacity of liver cytosol for 3H-dexamethasone at the second hour after the toxin administration. 4. In in vivo experiments endotoxin inhibited with 57.2% the binding of 3H-dexamethasone to hepatic nuclei. 5. It is suggested that the lower extent of endotoxin inhibition of GC induction of TAT may be due to the counteracting action of some inductor(s) for TAT only.