A role for effectors of cellular immunity in epimorphic regeneration of amphibian limbs.

Immune modulation of regeneration of amphibian appendages is suggested, but not proven, by previous studies. Earlier studies have not demonstrated effects of treatments on both epimorphic regeneration and immune responses or restoration of regeneration by specific reversal of immunomodulation. Cyclosporin A (CsA) and interleukin-2 (IL-2) were used in this study to demonstrate the effects of immune suppression and its reversal, on allograft rejection and forelimb regeneration.

Differential inflammatory and immunological responses in tissue regeneration and repair.

Repair and regeneration, contrasting resolutions to injury, evoke distinct inflammatory responses. Wound repair evokes a more robust peripheral leukocytosis and is accompanied by a larger inflammatory infiltrate into the wound site. Proliferation of thymocytes and splenocytes was enhanced following injury; however, the ability to be stimulated by myoblasts in coculure is lost by splenocytes harvested from rats undergoing wound repair.

Cyclic nucleotide metabolism during amphibian forelimb regeneration : II. The protein kinases.

The hypothesis that cAMP mediates neural and endocrine influences on limb regeneration was examined by studying the protein kinases in regenerating limb tissues. Since these enzymes are the vehicles through which cAMP acts intracellularly, an understanding of changes in their concentrations and behaviors during regeneration can be instrumental in elucidating the role of cAMP in this process. Mean activities oscillated throughout regeneration with maximal activities being observed during the mid-late bud stage.

Cyclic nucleotide metabolism during amphibian forelimb regeneration : I. The cyclic AMP phosphodiesterases.

Concentrations of the cyclic nucleotides in regenerating limb tissues change in a manner which suggests that they might mediate neural or endocrine influences upon specific developmental events. Since modulation of the role of cAMP within this process can be achieved through cAMP phosphodiesterase, enzymatic activity, relative intracellular distribution, and the kinetic parameters of this enzyme were examined at several stages of limb regeneration in adultNotophthalmus viridescens. Both forms of the phosphodiesterase displayed decreased activity about the time of bud formation.

Limb regeneration of the adult newt (Notophthalmus viridescens) in the absence of the spleen.

It has been suggested that the immune system might figure prominently in the regulation of forelimb regeneration. However, neither the nature of this influence nor the aspect(s) of regeneration influenced are clearly known. The determination of which components of the immune system are indispensable for regeneration would be a logical first step in attempting to address such questions.

The effects of hypophysectomy upon the endogenous levels of cyclic AMP during forelimb regeneration of adult newts (Notophthalmus viridescens).

Cyclic AMP is believed to play a role in limb regeneration. Using high pressure liquid chromatography, endogenous levels of cyclic AMP in regenerating tissues of normal and of hypophysectomized adult newts were estimated. In normally regenerating limbs, cyclic AMP levels were depressed 7 days after amputation and were elevated at 14 and 21 days.