SYMPATHETIC DENERVATION OF THE RAT VAS DEFERENS FOLLOWING UNILATERAL VASECTOMY

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Abstract
SUMMARY: 1. This paper describes an investigation of the time course of changes in noradrenaline levels in epididymal and prostatic segments of rat vasa deferentia, for up to 91 days following unilateral vasectomy by medial transection, together with an investigation of the responses of isolated preparations of these segments to field stimulation of sympathetic terminals.2. No atrophy of testes or seminal vesicles, or of the prostatic and epididymal segments of operated vasa deferentia, was evident at 2, 4, 7, 28 and 91 days after unilateral vasectomy.3. Spectrophotofluorometric assay revealed that noradrenaline levels in epididymal segments of operated vasa deferentia declined rapidly (within 2 days) after unilateral vasectomy and remained below 10% of those in unoperated epididymal segments at days 4, 7, 28 and 91 post‐vasectomy. Noradrenaline levels in prostatic segments of operated vasa deferentia were unaffected by vasectomy.4. Histochemical studies revealed that catecholamine fluorescence in epididymal segments of operated vasa deferentia declined in parallel with the decline in tissue noradrenaline levels; no comparable changes occurred in prostatic segments.5. Field stimulation (10 pulses, 60 V, 1 ms, applied at 0.1–50 Hz) evoked frequency‐dependent contractions of unoperated epididymal segments and of operated and unoperated prostatic segments at 2, 4, 7, 28 and 91 days post‐vasectomy. At day 2 and 4 responses of prostatic segments of operated tissues, to frequencies below 5 Hz, exceeded those of corresponding unoperated segments, however, by day 91, there was a small but significant decline in responses. Responses of epididymal segments of operated vasa deferentia to all frequencies of stimulation declined by day 2 post‐vasectomy and were absent thereafter except in three of the 18 preparations studied at day 91.6. These results, taken together, confirm that there is a rapid decline in catecholamine levels in the epididymal segment of medially transected vasa deferentia following unilateral vasectomy. Minimal, if any, reinnervation of this segment occurs during the 3 month period following unilateral vasectomy.