Arachidonic acid metabolites, secretion

Fig. 1. A model for the pleiotropic effects of LH on functions of Leydig cells. LH interacts with its specific receptor in the plasma membrane of the Leydig cell which results in the activation of several transducing systems and the formation of several second messengers (cyclic AMP, Ca2+, diacylglycerol and arachidonic acid metabolites). Protein kinases (A, C and calmodulin dependent) are activated resulting in the phosphorylation of specific proteins and the synthesis of specific proteins. The (phospho)proteins are involved in the transport of cholesterol to, and the control of, cholesterol metabolism in the inner mitochondrial membrane. Arachidonic acid metabolites (prostaglandins, leukotrienes) may also control steroidogenesis. LH can also regulate the secretion of proteins. The trophic effects of LH are manifested in the growth and differentiation of the Leydig cells.

Secretion of arachidonic acid metabolites (E series prostaglandins) to protect the gastric mucosa... 

Secretion of eosinophil-active cytokines such as IL-5 is not the only mechanism by which mast cells may mediate the LAR. Other cytokines such as IL-4 are also secreted by mast cells (62), and IL-4 might indirectly mediate the LAR through its upregulatory effects on T cells or epithelial cells (63-65). In addition, other mast cell mediators such as arachidonic acid metabolites may cause activation of airway epithelial cells or macrophages, setting off a cascade of events... 

Rouzer CA, Scott WA, Hamill AL, Liu FT, Katz DH, Cohn ZA. Secretion of leuko-triene C and other arachidonic acid metabolites by macrophages challenged with immunoglobulin E immune complexes. J Exp Med 1982 156(4) 1077-1086. 

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