Changes in receptor location affect the ability of oxytocin to stimulate proliferative growth in prostate epithelial cells.

In normal prostate cells, cell membrane receptors are located within signalling microdomains called caveolae. During cancer progression, caveolae are lost and sequestered receptors move out onto lipid rafts. The aim of this study was to investigate whether a change in the localisation of receptors out of caveolae and onto the cell membrane increased cell proliferation invitro, and to determine whether this is related to changes in the cell signalling pathways. Normal human prostate epithelial cells (PrEC) and androgen-independent (PC3) cancer cells were cultured with 10nM dihydrotestosterone (DHT). The effects of oxytocin (OT) and gonadal steroids on proliferation were assessed using the MTS assay. Androgen receptor (AR) and oxytocin receptor (OTR) expression was identified by immunofluorescence and quantified by western blot. OTR and lipid raft staining was determined using Pearson's correlation coefficient. Protein-protein interactions were detected and the cell signalling pathways identified. Treatment with OT did not affect the proliferation of PrEC. In PC3 cells, OT or androgen alone increased cell proliferation, but together had no effect. In normal cells, OTR localised to the membrane and AR localised to the nucleus, whereas in malignant cells both OTR and AR were identified in the cell membrane. Colocalisation of OTR and AR increased following treatment with androgens. Significantly fewer OTR/AR protein-protein interactions were seen in PrEC. With OT treatment, several cell signalling pathways were activated. Movement of OTR out of caveolae onto lipid rafts is accompanied by activation of alternative signal transduction pathways involved in stimulating increased cell proliferation.

The anatomy of the hip abductor muscles.

The anatomy of the hip abductors has not been comprehensively examined, yet is important to understanding function and pathology in the gluteal region. For example, pathology of the hip abductor muscle-tendon complexes can cause greater trochanteric pain syndrome, and may be associated with gluteal atrophy and fatty infiltration. The purpose of this study was to investigate the detailed morphology of gluteus medius (GMed), gluteus minimus (GMin), and tensor fascia lata (TFL), and determine whether the muscles comprised anatomical compartments. The gluteal region from 12 cadavers was dissected and data collected on attachment sites, volume, fascicular and tendinous anatomy, and innervation. Three sites of GMed origin were identified (gluteal fossa, gluteal aponeurosis, and posteroinferior edge of the iliac crest) and the distal tendon had lateral and posterior parts. GMed was the largest in volume (27.6 ± 11.6 cm(3); GMin 14.1 ± 11.1 cm(3); TFL 1.8 ± 0.8 cm(3)). Fascicles of GMin originated from the gluteal fossa, inserting onto the deep surface of its distal tendon and the hip joint capsule. TFL was encapsulated in the fascia lata, having no bony attachment. Primary innervation patterns varied for GMed, with three or four branches supplying different regions of muscle. Distinct secondary nerve branches entered four regions of GMin; no differential innervation was observed for TFL. On the basis of architectural parameters and innervation, GMed, and GMin each comprise of four compartments but TFL is a homogenous muscle. It is anticipated that these data will be useful for future clinical and functional studies of the hip abductors.

Hip abductor muscle volume in women with lateral hip pain: a case-controlled study.

UNLABELLED: Pathology of the hip abductor muscles and their associated tendons is implicated in the aetiology of lateral hip pain (LHP). Muscle atrophy is an important factor to consider in the diagnosis of this condition as it could result in reduced muscle volume and associated decreases in strength. PURPOSE: (1) To estimate the volumes of the gluteus medius (GMed), gluteus minimus (GMin) and tensor fascia lata (TFL) muscles, and (2) to examine pathological changes of the soft tissues in the vicinity of the hip joint, in women with and without LHP. METHODS: Twenty female participants (10 with LHP and 10 age-matched controls) underwent magnetic resonance imaging. Two radiologists reviewed the images for signs of pathological changes. Hip abductor muscle volumes were estimated using cross-sectional areas and Cavalieri's method. Differences in volume between sides, study groups and the three muscles were assessed. RESULTS: The volume of GMed was the largest (292.5 ± 33.3 cm3), followed by GMin (82.1 ± 12.1 cm3), then TFL (49.7 ± 18.9 cm3). No differences were evident in the volumes of the hip abductor muscles in individuals with LHP when compared to age- and sex-matched controls (GMed, p = 0.30; GMin, p = 0.40; TFL, p = 0.90). Pathology of the soft tissues was not specific to the symptomatic hips. CONCLUSIONS: Novel muscle volume data are presented for GMed, GMin and TFL in the context of LHP. Further research is needed to determine if symptom severity and duration have an impact on the extent of muscle atrophy in this population.

Changes in caveolae, caveolin, and polymerase 1 and transcript release factor (PTRF) expression in prostate cancer progression.

BACKGROUND: Caveolae are specialized invaginations in the cell membrane involved in the regulation of cell transport and signal transduction. The aims of this study were to investigate the number of caveolae and expression of caveolae-associated proteins, caveolin-1 and -2, and polymerase 1 and transcript release factor (PTRF) with development of prostate cancer. METHODS: Transmission electron microscopy was used to investigate the number of caveolae in normal human prostate stromal, epithelial cells, and androgen-dependent (LNCaP) and androgen-independent (PC3) cancer cell lines. Surgical tissue was obtained from patients with benign prostatic hyperplasia (BPH), well-differentiated and poorly differentiated prostate cancer. Caveolin-1, caveolin-2, and PTRF expression was identified by immunohistochemistry in tissue samples and quantified by Western blot analysis in cell lines. RESULTS: Caveolae were identified in normal epithelial and stromal prostate cells. The number of caveolae was significantly reduced in LNCaP and PC3 cells (P < 0.0001). PTRF was localized to stromal and epithelial cells in tissue from patients with BPH and in normal stromal and epithelial cells in vitro. PTRF expression was significantly decreased in LNCaP and PC3 cells and also in cancer tissue. In prostate tissue, caveolin-1 and -2 expression appeared to increase in prostate cancer. Caveolin-1 and -2 expression was decreased in LNCaP cells but caveolin-2 expression was significantly increased in PC3 cells compared to normal epithelial cells. CONCLUSIONS: This study demonstrates that changes in the cell membrane involving loss of caveolae and PTRF expression occur with the development of prostate cancer. These changes are accompanied by an up-regulation of caveolin-2.

The effects of oestrogen receptors alpha and beta on testicular cell number and steroidogenesis in mice.

Oestrogen plays an important role in testicular function. This study used mice null for oestrogen receptor alpha (ER alpha) or beta (ER beta) to investigate which receptor mediates the effects of oestrogen within the testis. Groups of ER alpha knockout mice (alpha ERKO) and ER beta knockout mice (beta ERKO) and wild-type littermates (n=5-8) were killed at 11 weeks post partum. One testis was fixed in Bouin's fluid for stereology and the other frozen for testosterone measurement. Trunk blood was collected for testosterone RIA. The optical disector combined with the fractionator methodology was used to estimate Leydig, Sertoli and germ cell numbers. At all times, the knockout animals were compared with their wild-type littermates. The physical disector quantified cells stained immunohistochemically for the apoptotic marker active caspase-3 and Hoechst staining was used to identify nuclear fragmentation. The mean Leydig cell volume was measured using the point sampled intercept method. The Leydig cell number per testis was significantly increased in beta ERKO mice but not in alpha ERKO mice. Plasma and testicular testosterone concentrations were increased in alpha ERKO mice but no changes were observed in beta ERKO mice. Hypertrophic Leydig cell changes were observed in alpha ERKO mice, and a decreased mean cell volume was seen in beta ERKO mice. No difference in Sertoli cell number per testis was observed in any of the groups. The spermatogonial cell number per testis was increased in beta ERKO mice. Immunohistochemistry identified increased numbers of active caspase-3-labelled germ cells per testis in alpha ERKO mice but not beta ERKO mice. Hoechst staining supported these findings. There was significant germ cell loss in alpha ERKO mice. This study suggests that ER beta may be involved in regulation of Leydig cell proliferation and testosterone production in the adult mouse testis.

A comparison of different embalming fluids on the quality of histological preservation in human cadavers.

There are significant problems in obtaining normal human material for histology for teaching or research purposes. This study shows that tissue from cadavers embalmed for teaching can be used for routine histology. Twelve cadavers embalmed with four different formalin-containing embalming fluids were used (n = 3 per fluid): (1) formalin mix (10% formalin); (2) Dunedin mix (an alcohol-based fluid containing phenol); (3) Michigan mix (a water-based fluid); and (4) phenoxyethanol mix (an alcohol-based fluid containing phenoxyethanol). Tissue blocks of liver, heart, kidney, skin and skeletal muscle were taken from each cadaver, paraffin embedded, sectioned and stained with haematoxylin and eosin (H & E), Periodic Acid Schiff (PAS), or Mallory trichrome (Malt). Each section was assigned an overall score based on the histological quality of the cellular components of the tissue. Sections were scored from 1 to 3 (1 = poor, 2 = satisfactory, 3 = good). Satisfactory sections were obtained from all cadavers except those embalmed with the Dunedin mix. The Michigan and phenoxyethanol fluids resulted in consistently good quality sections. No significant differences in tissue morphology were observed between the different stains. The clearest morphology was observed in the skin and skeletal muscle sections, and in tissues embalmed with fluids which do not contain phenol.

Regulation of 5alpha-reductase isoforms by oxytocin in the rat ventral prostate.

Oxytocin (OT) is present in the male reproductive tract, where it is known to modulate contractility, cell growth, and steroidogenesis. Little is known about how OT regulates these processes. This study describes the localization of OT receptor in the rat ventral prostate and investigates if OT regulates gene expression and/or activity of 5alpha-reductase isoforms I and II. The ventral prostates of adult male Wistar rats were collected following daily sc administration of saline (control), OT, a specific OT antagonist or both OT plus antagonist for 3 d. Expression of the OT receptor was identified in the ventral prostate by RT-PCR and Western blot, and confirmed to be a single active binding site by radioreceptor assay. Immunohistochemistry localized the receptor to the epithelium of prostatic acini and to the stromal tissue. Real-time RT-PCR determined that OT treatment significantly reduced expression of 5alpha-reductase I but significantly increased 5alpha-reductase II expression in the ventral prostate. Activity of both isoforms of 5alpha-reductase was significantly increased by OT, resulting in increased concentration of prostatic dihydrotestosterone. In conclusion, OT is involved in regulating conversion of testosterone to the biologically active dihydrotestosterone in the rat ventral prostate. It does so by differential regulation of 5alpha-reductase isoforms I and II.

Effects of steroids on oxytocin secretion by the human prostate in vitro.

Oxytocin (OT) concentrations are elevated in prostate tissue of patients with benign prostatic hyperplasia (BPH). Oxytocin specifically increases growth, 5 alpha-reductase activity and contractility in the prostate. In the rat prostatic OT concentrations are regulated by gonadal steroids, with androgens reducing but oestrogens increasing OT concentrations. The regulation of prostatic oxytocin in man is not understood. This study investigates the effects of gonadal steroids on oxytocin production by the human prostate. Primary explants (approx. 1 mm3) of prostate tissue from patients with BPH were incubated in Dulbecco's modified Eagle's media in the absence or presence of 10 nmol/L testosterone (T), 10 nmol/L dihydrotestosterone (DHT), T or DHT plus 100 nmol/L of the anti-androgen cyproterone acetate (CPA), 55 pmol/L diethylstilbestrol (DES), or DES plus DHT. The amount of oxytocin secreted into the media after 3 days was measured by radioimmunoassay. Testosterone and DHT significantly increased oxytocin concentrations secreted into the media from 0.86 +/- 0.11 ng/g of tissue (control) to 1.51 +/- 0.14 ng/g (p < 0.01) and 1.54 +/- 0.13 ng/g (p < 0.05), respectively. Incubation of tissue samples with CPA resulted in oxytocin concentrations similar to control levels. Treatment with DES caused a significant increase from 1.99 +/- 0.71 to 3.98 +/- 1.36 ng/g (p < 0.05). A similar increase was measured in media of tissue incubated in DES plus DHT (p < 0.001). The results demonstrate that, unlike the rat where androgens decrease oxytocin, in hyperplastic human prostate tissue both androgens and oestrogens increase oxytocin. This imbalance in the regulation of oxytocin may result in promoting prostatic overgrowth in the pathogenesis of BPH.

Clinical anatomy research in a research-driven anatomy department.

Clinical anatomy is too often viewed as a discipline that reiterates the wisdom of the past, characterized more by description of what is known than by active investigation and critical analysis of hypotheses and ideas. Various misconceptions follow from an acceptance of this premise: the teaching of clinical anatomists is textbook based, there is no clinical anatomy research worthy of the name, and any research that does exist fails to utilize modern technology and does not stand comparison with serious biomedical research as found in cell and molecular biology. The aim of this paper is to challenge each of these contentions by reference to ongoing clinical research studies within this department. It is argued that all teaching (including that of clinical anatomy) should be research-informed and that the discipline of clinical anatomy should have at its base a vigorous research ethos driven by clinically related problems. In interacting with physicians, the role of the clinical anatomist should be to promulgate a questioning scientific spirit, with its willingness to test and challenge accepted anatomic dicta.

Oxytocin promotes spermiation and sperm transfer in the mouse.

Spermatogenesis is a complex process during which developing germ cells move from the base of the seminiferous tubule towards the lumen where they are shed. Studies in the rat suggest that seminiferous tubule contraction, induced by exogenous oxytocin, promotes spermiation. This study examines the role of testicular oxytocin in development of the testes, spermatogenesis and spermiation in the mouse. Groups of wild-type (WT) mice, oxytocin knockout mice (OTKO) deficient in testicular oxytocin and mice containing an oxytocin transgene (bOT4.2) that over express testicular oxytocin were killed between days 5 and 45 post partum. The testes and epididymides were removed weighed and prepared either for histological and morphometric study by light microscopy, for sperm counts (epididymis), or extracted for determination of oxytocin content (testis - day 45 only). Testicular oxytocin concentrations were significantly greater (p < 0.05) in bOT4.2 mice than in WT or OTKO mice. No differences in testicular and epididymal weight, or in diameter and area of seminiferous tubules between the mice genotypes were found at any given time. Germ cell development was similar in all genotypes and was comparable with previous studies. The timing of spermiation between the groups was significantly different (p < 0.001) with bOT4.2 < WT < OTKO and the appearance of epididymal sperm was significantly different (p < 0.05) with bOT4.2 < WT < OTKO. There were significant correlations between the percentage of tubules containing residual bodies and epididymal sperm count (p < 0.05) and between the percentage of animals containing residual bodies and the percentage of animals containing epididymal sperm (p < 0.01). These data suggest that in the mouse oxytocin, whilst not involved in germ cell development, is important in the process of spermiation and sperm transfer in the mouse.

Function and localization of oxytocin receptors in the reproductive tissue of rams.

Oxytocin is present in the male reproductive tract and has been shown to increase contractility in the epididymis and to modulate steroidogenesis. This study investigated the effects of oxytocin in the testis in vivo, and the presence and cellular localization of oxytocin receptors in the reproductive tract of rams. During the breeding season, mature rams underwent efferent duct ligation before injection of either oxytocin (20 microg) or oxytocin plus an oxytocin antagonist (20 microg) into the testicular artery; the contralateral testicular artery received saline. Injection of oxytocin caused a significant increase (P < 0.05) in the concentration of spermatozoa collected from the rete testis. This effect was not observed after treatment with the oxytocin antagonist plus oxytocin. Western blot analysis performed using a specific oxytocin receptor antibody (020) identified a single immunoreactive band of 66 kDa in testicular and epididymal tissue. This band was present in uterine tissue but not in liver or muscle. Immunocytochemistry identified oxytocin receptors on Leydig and Sertoli cells of the testis, on epithelial cells throughout the epididymis, on peritubular smooth muscle cells in the cauda epididymidis, and on the epithelial cells and circular smooth muscle layer of the ductus deferens. These findings indicate that oxytocin can modulate sperm transport in the ram testis. A role for oxytocin in promoting sperm transit is supported by the localization of oxytocin receptors in the cauda epididymis and ductus deferens, and the presence of receptors on Leydig, Sertoli and epididymal epithelial cells provides further evidence that oxytocin may be involved in the local regulation of steroidogenesis.

Oxytocin and vasopressin expression in the ovine testis and epididymis: changes with the onset of spermatogenesis.

Contractions of seminiferous tubules and epididymal duct walls promote spermiation and sperm transfer, and they are thought to be stimulated by the related peptides oxytocin and vasopressin. This study tested the hypothesis that if oxytocin and/or vasopressin play a physiological role in sperm shedding and transport, then local or circulating concentrations of these peptides would increase during puberty. Testes, epididymides, and trunk blood of sheep at stages during the first spermatogenic wave were collected, and radioimmunoassay measured significant increases in testicular and epididymal oxytocin during spermatogenesis. No changes were measured in circulating oxytocin or in local or circulating vasopressin. Localization and synthesis was investigated by immunohistochemistry and Western blot analysis employing antibodies recognizing epitopes of either oxytocin, oxytocin-associated neurophysin, vasopressin, or vasopressin-associated neurophysin. Marked expression of both oxytocin and its associated neurophysin in testicular Leydig and epididymal principal cells was seen, and weak neurophysin immunoreactivity was also identified in Sertoli cells. The intercellular distribution of oxytocin varied between regions of the epididymis, suggesting several roles for oxytocin. Vasopressin synthesis was not apparent in either tissue. These results confirm the presence and development of paracrine oxytocinergic systems in the ram testis and epididymis of ram during puberty while questioning the physiological importance of vasopressin.

Evidence for the regulation of prostatic oxytocin by gonadal steroids in the rat.

Oxytocin and its receptor are present in the mammalian prostate, and the peptide has been shown to increase prostatic growth, 5alpha-reductase activity, and contractility. This study was performed to investigate whether local concentrations of the peptide were regulated by gonadal steroids in order to establish whether oxytocin has a physiological role in the prostate. Both intact and castrated adult Wistar rats were treated daily for 7 days with either testosterone propionate or the antiandrogen cyproterone acetate. Animals were then killed, and plasma hormone and prostatic oxytocin concentrations were measured. A separate group of rats was treated with the 5alpha-reductase inhibitor finasteride to investigate whether testosterone or dihydrotestosterone (DHT) was involved in regulating oxytocin concentrations. In a further series of experiments, rats were treated with diethylstilbestrol (DES) or the antiestrogen tamoxifen. Treatment with testosterone significantly decreased prostatic oxytocin, whereas reduction of androgens by castration or by administration of cyproterone acetate increased prostatic peptide concentrations without altering circulating levels of the peptide. Treatment with finasteride increased plasma testosterone but decreased DHT concentrations. Prostatic oxytocin concentrations were higher in finasteride-treated animals than in control animals with comparable testosterone levels. The data suggest that both testosterone and DHT are capable of decreasing prostatic oxytocin concentrations. Treatment with DES did not significantly alter prostatic oxytocin, but administration of tamoxifen decreased concentrations of the peptide, suggesting that low levels of estrogen may be necessary for oxytocin production. These data provide evidence that oxytocin is regulated by androgens, and we hypothesize that this regulatory mechanism may be involved in controlling prostatic growth.

Effects of oxytocin and vasopressin on sperm transport from the cauda epididymis in sheep.

This study was performed to determine whether oxytocin or vasopressin affect the transport of spermatozoa from the epididymis of rams in vivo. Under general anaesthesia, cannulae were inserted into each ductus deferens and passed into the cauda epididymis of 24 Oxford Down cross rams and the luminal fluid was collected at 10 min intervals for 2-3 h. Animals were divided into seven groups and received either (i) 2 ml 0.9% saline, (ii) 10 micrograms oxytocin, (iii) 100 micrograms oxytocin, (iv) 100 micrograms oxytocin antagonist, (v) 300 micrograms oxytocin antagonist followed by 100 micrograms oxytocin, (vi) 100 micrograms vasopressin, or (vii) 100 micrograms vasopressin followed by 100 micrograms oxytocin, all by i.v. injection. The mass of fluid and number of spermatozoa in each 10 min sample was measured and the motility of the spermatozoa was assessed. Treatment with saline did not affect the mass or the number of spermatozoa in the fluid collected. Oxytocin at 10 micrograms significantly increased both the output of fluid and the number of spermatozoa by twofold. Oxytocin at 100 micrograms produced a greater increase in both fluid output and the number of spermatozoa within 10 min of administration of the peptide. Treatment with oxytocin antagonist had no immediate effect, but subsequently caused a significant reduction in both fluid output and the number of spermatozoa. Pretreatment with oxytocin antagonist inhibited the stimulatory effect of oxytocin. Vasopressin did not increase the number or concentration of spermatozoa in the fluid and appeared to decrease fluid output. No significant changes in the morphology or motility of the spermatozoa collected was observed in any of the samples. These data demonstrate that oxytocin has specific actions on the epididymis to increase sperm transport. They indicate that local oxytocin may be involved in regulating basal contractility of the cauda epididymidis and that augmentation by the peptide in the peripheral circulation, as occurs around the time of ejaculation, may promote a significant increase in the transport of spermatozoa into the vas deferens and ejaculate.

Stage-related differences in rat seminiferous tubule contractility in vitro and their response to oxytocin.

Oxytocin (OT) is present in the mammalian testis and has been shown to play a role in the modulation of seminiferous tubule contractility and steroidogenesis. However, stage-specific effects of the peptide have not been previously investigated. In this study, computer-assisted analysis and time-lapse videomicrography were used to investigate basal contractility and the response to OT of seminiferous tubules at specific stages of the spermatogenic cycle. Adult rat testes were placed in fresh oxygenated DMEM F12 medium, decapsulated, and the tubules gently teased apart. Stages were identified by transillumination and a 10 mm section of tubule at each of stages IV-V, VII-VIII and XIII-I was placed in a microslide chamber and perifused with medium. After a control period of 3 h, OT (2 nM) was given for 1 h, followed by another control period of 1 h. The experiment was repeated using tubules from different rats and data were analysed to give arbitrary units of tubule contractility. Contractility was observed in all the tubules studied and the contractile activity was shown to vary depending on the stage of the spermatogenic cycle. Mean basal contractility at stages VII-VIII, the time when sperm are shed from the epithelium, was significantly lower than that at stages IV-V and XIII-I. The response of the tubules to OT was also stage-dependent, with the peptide producing the largest increases in contractile activity at stages VII-VIII and having no effect at stages IV-V. We postulate that these stage-specific differences in basal and OT-stimulated contractility may be important in co-ordinating the movement of developing germ cells towards the lumen of the seminiferous epithelium and in the process of spermiation.

Localization of oxytocin receptors in the human and macaque monkey male reproductive tracts: evidence for a physiological role of oxytocin in the male.

The peptide oxytocin is present in tissues of the male reproductive tract from a variety of mammalian species. In the human, specific mRNA for oxytocin and the peptide itself have been identified in the testis, epididymis and prostate. The peptide has been shown to modulate both steroidogenesis and contractility in the male reproductive tract and may be involved in the pathogenesis of benign prostatic hyperplasia. We have performed Western blots and immunohistochemistry using a specific antibody to the human oxytocin receptor (OTR) to investigate the distribution and localization of the receptor in the human and macaque monkey (Macaca fasicularis). An immunoreactive band of approximately 55 kDa was detected in human and monkey uterine, testicular and prostatic tissues and in preparations of monkey caput and cauda epididymis. A second, less intense, band of 60 kDa was also seen in testicular and uterine tissue samples. No specific bands were detected in monkey muscle or in any tissue following incubation with mouse immunoglobulin (Ig)M. In the human and monkey testis staining for the OTR was present in the interstitial tissue and in Sertoli cells. Localization of the OTRs varied throughout the epididymis being expressed by epithelial cells proximally but confined to cells at the base of the epididymal ducts and to the surrounding smooth muscle layers distally. In the prostate OTR were localized to the stromal tissue surrounding the ducts. These findings correlate with sites of local production of the peptide and the observed biological actions of oxytocin, and thus support the evidence that oxytocin may play a physiological role in the male reproductive tract.

Characterisation of the biological effects of neurohypophysial peptides on seminiferous tubules.

Oxytocin (OT) is present in the mammalian testis and has been postulated to play a role in modulation of seminiferous tubule contractility. However, recent evidence suggests that the myoid cells responsible for such contractile activity do not express OT receptors. In this study computer-assisted analysis and time-lapse videomicrography were used to investigate the biological effects of neurohypophysial peptides and their analogues on seminiferous tubule contractility. Adult rat testes were placed in fresh oxygenated Dulbecco's modified Eagle's medium (DMEM) F12 medium, decapsulated and the tubules gently teased apart. A small section of tubule was placed in a microslide chamber and perifused with medium. Seminiferous tubules were treated with OT (2 nM), [Arg8]-vasopressin (AVP, 0.2 nM) or [Thr4,Gly7]-OT (TGOT, 2 nM, 8 nM and 0.2 microM). Specific antagonists were also given simultaneously with OT and AVP treatments. Data were analysed to give arbitrary units of contractility. Both OT and AVP increased tubule contractility, with AVP being at least 10 times more potent than OT. Treatment with the selective OT antagonist, desGly-NH2,d(CH2)5[d-Tyr2,Thr4]-ornithine vasotocin (OTA, 0.2 microM and 2 microM) significantly reduced OT-induced increases in seminiferous tubule contractility but had no effect on AVP-induced responses. In contrast, the AVP antagonist, Phaa-d-Tyr(Me)-Phe-Gln-Asn-Arg-Pro-Arg-Tyr-NH2 (AVPA) was more potent at reducing AVP-induced increases than OT-induced responses. The selective non-peptide AVPA SR 49059 blocked the response to both peptides in a similar manner, whilst the non-peptide OTA L367,773 did not block OT-induced increases in seminiferous tubule contractility at doses that were slightly inhibitory to AVP-induced responses. The specific OT agonist TGOT did not induce a contractile response. The data in this study demonstrate that in the testis AVP acts via V1a receptors to stimulate contractile activity and suggest that OT may act via a receptor which differs from the classical V1a and uterine-type OT receptor. These findings support a role for OT in the regulation of seminiferous tubule contractility and raise the possibility that AVP may also be important in this process.

The extended lateral approach to the hindfoot. Anatomical basis and surgical implications.

We have recently described an extended lateral approach to the hindfoot for the operative treatment of displaced intra-articular fractures of the calcaneum. It has the advantage of avoiding damage to the sural nerve and preserving blood supply to allow prompt healing. We dissected 15 formalin-preserved cadavers, taking photographs to show the structures of the posterolateral aspect of the hindfoot and ankle. We describe a superficial and a deep triangle: the deep triangle contains a constant posterior peroneal artery which supplies the skin of the posterolateral heel. An approach designed to expose the sural nerve will divide this important artery and cause ischaemia of the posterior skin. The extended lateral approach elevates the sural nerve in a thick flap and preserves the blood supply of the skin. We have reviewed 150 consecutive patients after the use of this approach to study the indications for operation, the quality of wound healing, any damage to the sural nerve and other complications. We recommend the careful use of this approach. Our understanding of its anatomical basis has allowed us to widen the indications for its use.

Determination of a standard site for the measurement of bone mineral density of the human calcaneus.

Ultrasound of the calcaneus may be used as a cheap, ionising radiation-free and easy to use indicator of skeletal status, and hence of osteoporotic fracture risk. At present ultrasound is not widely used as it suffers from high precision errors. As ultrasound parameters are determined in part by bone mineral density (BMD), an increase in the accuracy and precision of BMD measurements should reduce the precision error associated with ultrasound measurements. The aim of this study was to define an anatomical site on the calcaneus at which accurate and precise measurements of BMD can be made. Ten dry calcanei and 10 cadaveric feet were scanned using a DXA scanner; 9 anatomically defined regions (1 cm2) were selected in the posterior part of the calcaneus for analysis. The centre of region 1 was positioned halfway along the line joining the anterior border of the calcaneal tubercle and the peak of the posterior superior tubercle, and the remaining 8 regions were placed around this central area. The BMD in these 9 regions was compared with the whole bone BMD and the variability of BMD within each of the 9 regions was measured. The reproducibility of the technique was assessed by taking 10 repeated measurements of 2 bone and 2 cadaveric specimens, each specimen being removed and repositioned between measurements. Region 1 was found to be the most representative of total BMD in cadaveric feet. This region also showed the least variability of BMD and consistently gave the lowest coefficients of variation in the reproducibility study both in the bone and the cadaveric specimens. This region is hence the most suitable site on the calcaneus for measuring absolute values of and changes in BMD. The surface position of region 1 was found to be consistently 5/9 along the line at 45 degrees to the vertical, from the lateral malleolus to the heel. The identification of the surface location of region 1 relative to anatomical landmarks of the foot has enabled the same anatomical site to be measured in all subjects. This allows meaningful intersubject comparisons to be made. Preliminary data suggest that precision errors using ultrasound are also reduced when measurements are taken at this region of the calcaneus. The reduction in the precision error of ultrasound assessment of skeletal status may provide a cheap and safe way to identify individuals at risk from osteoporotic fracture.

Epididymal oxytocin in the rat: its origin and regulation.

Oxytocin is localized to the Leydig cells of the testis in the rat and several other species where it is postulated to play a role in steroidogenesis and seminiferous tubule contractility. Oxytocin has also been detected in the epididymis of the ram where active uptake of the peptide from luminal fluid has been demonstrated. This study was performed to investigate whether oxytocin is present in the rat epididymis, and the origin of the peptide. Immunoactive oxytocin was detected in the epididymis of all control animals examined (147.7 +/- 41.7 pg/g). Total epididymal oxytocin was reduced significantly following castration (p < 0.05). Testosterone treatment also reduced the epididymal concentration of the peptide in both intact and castrated rats. Efferent duct ligation (EDL) did not affect the presence of oxytocin in the epididymis. Immunoactive oxytocin was localized in discrete cells of the epithelium of the caput epididymis, with less staining apparent in the initial segment and cauda epididymis. Staining disappeared from the caput epididymis following castration, but reappeared following testosterone supplementation. No obvious alteration in staining was observed in the cauda epididymis after EDL. These data demonstrate for the first time the presence of oxytocin in the epididymis of the rat and that the peptide may be regulated by androgens. They further suggest an epididymal source of the peptide.