Despite the brain's central role in sexual function, little is known about relationships between brain activation and sexual response. In this study, we employed functional MRI (fMRI) to examine relationships between brain activation and sexual arousal in a group of young, healthy, heterosexual males. Each subject was exposed to two sequences of video material consisting of explicitly erotic (E), relaxing (R) and sports (S) segments in an unpredictable order. Data on penile turgidity was collected using a custom-built pneumatic pressure cuff. Both traditional block analyses using contrasts between sexually arousing and non-arousing video clips and a regression using penile turgidity as the covariate of interest were performed. In both types of analyses, contrast images were computed for each subject and these images were subsequently used in a random effects analysis. Strong activations specifically associated with penile turgidity were observed in the right subinsular region including the claustrum, left caudate and putamen, right middle occipital/ middle temporal gyri, bilateral cingulate gyrus and right sensorimotor and pre-motor regions. Smaller, but significant activation was observed in the right hypothalamus. Few significant activations were found in the block analyses. Implications of the findings are discussed. Our study demonstrates the feasibility of examining brain activation/sexual response relationships in an fMRI environment and reveals a number of brain structures whose activation is time-locked to sexual arousal.
The aim of this study was to investigate quantitative mRNA expression of matrix metalloproteinases MMP-1, MMP-2, MMP-9, and their inhibitors, the tissue inhibitors of metalloproteinases TIMP-1, TIMP-2 and TIMP-3, in vaginal wall tissue from women with stress urinary incontinence compared to continent controls. Vaginal wall tissues were obtained from 7 women with stress urinary incontinence/severe pelvic prolapse and 15 continent controls. RNA was then extracted and quantified. Quantitative competitive reverse transcription (QC-RT-PCR) was carried out with oligonucleotide primers to quantify MMP-1, MMP-2, MMP-9, TIMP-1, TIMP-2 and TIMP-3 mRNA expression. Stress continent women demonstrated a significant decrease in TIMP-1 and mRNA expression (P = 0.03). There was no difference in TIMP-2, TIMP-3, MMP-2 or MMP-9 mRNA expression between stress incontinent women and controls. However, MMP-1 mRNA expression was significantly increased (P = 0.05) in the incontinent group and the MMP-1/TIMP-1 ratio (P = 0.04) was consistent with increased collagen degradation in the stress incontinence. Stress incontinent women demonstrated an increase in MMP-1 mRNA expression and a decrease in the inhibitor TIMP-1 mRNA expression. Both these findings are consistent with increased collagen breakdown as a pathologic etiology of incontinence.
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