Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Truth Incorporated

What is the cognitive value of the concept of truth? What epistemic difference does the concept of truth make to those who grasp it? This paper employs a new perspective for thinking about the concept of truth and recent debates concerning it, organized around the question of the cognitive value of the concept of truth. The paper aims to defend a substantively correct and dialectically optimal account of the cognitive value of the concept of truth. This perspective is employed in understanding the critical discussion around what Hartry Field (2001a) has called “the incorporation model” for extending a deflationary view of truth to foreign sentences. Field's original intentions in discussing the incorporation model were to defend the deflationary view from some counterintuitive consequences concerning the understanding of truth attributions to foreign sentences. However, more recently, philosophers unencumbered by deflationary commitments have taken over the incorporation model for their own inflationary purposes. In particular, and in my terms, these philosophers can be understood as making what I argue is the ultimately too radical suggestion that the cognitive value of the concept of truth is to allow the incorporation not only of the linguistically foreign, but also of the conceptually alien. I clarify this dialectic en route to explaining and arguing for the cognitive inflationary view, according to which the cognitive value of the concept of truth is is to make possible the proprietary kind and quality of knowledge allowed by reflective clarity over the concepts and thoughts that one already has.     

Indeterminacy,A Priority,and Analyticity in the Quinean Critique

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