Beta-adrenoceptor blockade delays granulation tissue formation in polyurethane sponge implants.
BACKGROUND
The role of adrenoceptors in granulation tissue formation is not well understood. The aim of this study was to investigate the effects of alpha- and beta-adrenoceptor blockade on granulation tissue development using polyurethane (PU) implants in the rat.


METHODS
Animals were treated orally with propranolol (beta1- and beta2-antagonist), atenolol (beta1-antagonist) or phentolamine (alpha1- and alpha2-antagonist) until euthanasia. The control group received only water. All animals received subcutaneous implants of PU sponges. After 14 days, implants were collected, formalin-fixed and paraffin-embedded. Sections were stained with hematoxylin and eosin and Sirius red and immunostained for CD68 and alpha-smooth muscle actin.


RESULTS
The number of inflammatory cells and the volume density of myofibroblasts and blood vessels were lower in the control group than in the propranolol- and atenolol-treated groups. The collagen fiber score was greater in the control group than in the propranolol- and atenolol-treated groups. The inflammatory infiltrate, collagen fiber score, blood vessel density or myofibroblast differentiation was not affected by phentolamine. The percentage of fibrovascular invasion was greater in the antagonist-treated groups than in the control group.


CONCLUSIONS
Blockade of beta1- and beta2-adrenoceptors, but not alpha-adrenoceptors, impairs granulation tissue development in PU implants due to interference with the inflammatory response.
Romana-Souza
Bruna
B
Department of Histology and Embryology, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
Santos
Jeanine S
JS
Desmoulière
Alexis
A
Monte-Alto-Costa
Andréa
A
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D003094:Collagen / Q000187:drug effects; D006097:Granulation Tissue / Q000187:drug effects* / Q000473:pathology*; D007150:Immunohistochemistry; D020007:Implants, Experimental / Q000009:adverse effects; D008297:Male; D011140:Polyurethanes / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D011943:Receptors, Adrenergic, beta / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D011140:Polyurethanes; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D003094:Collagen