Immunohistochemical description of cyclic nucleotide phosphodiesterase (PDE) isoenzymes in the human labia minora.

INTRODUCTION

Up until now, only minimal research has been carried out on those female genital organs known to contribute to the normal cycle of sexual arousal and orgasm. Some findings indicated that there might be a significance of cyclic nucleotide-mediated pathways in the control of the normal function of female genital tissues.

AIM: To elucidate, by means of immunohistochemistry, the distribution of the phosphodiesterase (PDE) isoenzymes 1, 3, 4, 5, 10, and 11 in the human labia minora.

MAIN OUTCOME MEASURES: The amount of immunohistochemical staining specific for cyclic adenosine monophosphate (cAMP)- and/or cyclic guanosine monophosphate (cGMP)-degrading PDE isoenzymes was detected.

METHODS

Human labial tissue was obtained from four female cadavers (age at death: 18-42 years). Vibratome sections prepared from formaldehyde-fixated tissue specimens were incubated with primary antibodies directed against the respective PDE isoenzymes. Sections were then incubated with fluorochrome (fluorescein isothiocyanate, Texas Red)-labeled secondary antibodies. Visualization was commenced by means of a laser fluorescence microscope.

RESULTS

Immunostaining indicating the expression of PDE4 and PDE5 was abundantly observed in the smooth musculature of vessels interspersing the tissue. Immunoreactions specific for PDE3 were recognized in epithelial and subepithelial layers, sebaceous glands, and interstitial or neuroendocrine-like single cells located in the epithelium. Signals related to PDE10 and PDE11 were limited to the epithelium or glandular-like structures, respectively.

CONCLUSIONS

Our results, for the first time, demonstrate the presence of cAMP- and cGMP-PDE isoenzymes in the human labia minora and give a hint to a significance of PDE4 and PDE5 in the control of labial vascular tissue function.