Noise is an environmental physical agent, which is regarded as a stressful stimulus: impairment and modifications in biological functions are reported, after loud noise exposure, at several levels in human and animal organs and apparatuses, as well as in the endocrine, cardiovascular and nervous system In the present study equilibrium binding parameters of peripheral benzodiazepine receptors (PBRs) labelled by the specific radioligand [H-3]PK 11195, were evaluated in cardiac tissue of rats submitted to 6 or 12 h noise exposure and of rats treated "in vivo" with PER ligands such as PK 11195, Ro5-4864, diazepam and then noise-exposed. Results revealed a statistically significant decrease in the maximum number of binding sites (B-max) of [H-3]PK 11195 in atrial membranes of 6 or 12 h noise exposed rats, compared with sham-exposed animals, without any change in the dissociation constant (K-d) The "in vivo" PER ligand pretreatment counteracted the noise-induced modifications of PER density. As PBRs are mainly located on mitochondria we also investigated whether noise exposure can affect the [H-3]PK 11195 binding parameters in isolated cardiac mitochondrial fractions. Results indicated a significant B-max value decrease in right atrial mitochondrial fractions of rats 6 or 12 h noise- exposed. Furthermore, as PER has been suggested to be a supramolecular complex that might coincide with the not-yet-established structure of the mitochondrial permeability transition (MPT)-pore, the status of the MPT-pore in isolated heart mitochondria was investigated in noise- and sham-exposed rats. The loss of absorbance associated with the calcium-induced MPT-pore opening was greater in mitochondria isolated from hearts of 6 h noise-than those of sham-exposed rats. In conclusion, these findings represent a further instance for PER density decrease in response to a stressful stimulus, like noise; in addition they revealed that "in vivo" administration of PER ligands significantly prevents this decrease. Finally, our data also suggest the involvement of MPT in the response of an organism to noise stress.
Effect of noise exposure on rat cardiac peripheral benzodiazepine receptors
GESI, MARCO;PELLEGRINI, ANTONIO;GIANNACCINI, GINO;LUCACCHINI, ANTONIO;MARTINI, CLAUDIA
2000-01-01
Abstract
Noise is an environmental physical agent, which is regarded as a stressful stimulus: impairment and modifications in biological functions are reported, after loud noise exposure, at several levels in human and animal organs and apparatuses, as well as in the endocrine, cardiovascular and nervous system In the present study equilibrium binding parameters of peripheral benzodiazepine receptors (PBRs) labelled by the specific radioligand [H-3]PK 11195, were evaluated in cardiac tissue of rats submitted to 6 or 12 h noise exposure and of rats treated "in vivo" with PER ligands such as PK 11195, Ro5-4864, diazepam and then noise-exposed. Results revealed a statistically significant decrease in the maximum number of binding sites (B-max) of [H-3]PK 11195 in atrial membranes of 6 or 12 h noise exposed rats, compared with sham-exposed animals, without any change in the dissociation constant (K-d) The "in vivo" PER ligand pretreatment counteracted the noise-induced modifications of PER density. As PBRs are mainly located on mitochondria we also investigated whether noise exposure can affect the [H-3]PK 11195 binding parameters in isolated cardiac mitochondrial fractions. Results indicated a significant B-max value decrease in right atrial mitochondrial fractions of rats 6 or 12 h noise- exposed. Furthermore, as PER has been suggested to be a supramolecular complex that might coincide with the not-yet-established structure of the mitochondrial permeability transition (MPT)-pore, the status of the MPT-pore in isolated heart mitochondria was investigated in noise- and sham-exposed rats. The loss of absorbance associated with the calcium-induced MPT-pore opening was greater in mitochondria isolated from hearts of 6 h noise-than those of sham-exposed rats. In conclusion, these findings represent a further instance for PER density decrease in response to a stressful stimulus, like noise; in addition they revealed that "in vivo" administration of PER ligands significantly prevents this decrease. Finally, our data also suggest the involvement of MPT in the response of an organism to noise stress.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
