Recurrent Lumbar Disc Herniation: Does Transforaminal Lumbar Interbody Fusion Lead to Better Clinical and Radiological Outcomes than Redo-Discectomy?

STUDY DESIGN

randomized, prospective, and level I clinical study.

PURPOSE

To compare the clinical outcomes and radiological findings of revision discectomy alone versus revision discectomy with fusion as surgical treatment for recurrent lumbar disc herniation (RDH).

OVERVIEW OF LITERATURE

RDH is a common complication following a primary discectomy. The optimal surgical procedure for RDH is still debated.

METHODS

Sixty patients with RDH were randomly divided into two equal groups: the first group underwent revision discectomy alone and the second underwent revision discectomy with fusion. The primary outcomes evaluated were Visual Analog Scale (VAS) for low back and limb pains, Oswestry Disability Index (ODI), disc height indexes, foraminal height index, and disc height subsidence. Secondary outcomes included operative time, blood loss, postoperative hospital stay, and complications.

RESULTS

Revision discectomy with fusion showed superior pain relief and improved functional outcomes, including better VAS scores for both back and leg pain and ODI at 24-month follow-up. Additionally, it restored the stability of the spine better with lower disc height subsidence without significant complications. However, these advantages came at the cost of increased blood loss and longer operative time and hospital stays.

CONCLUSIONS

Revision discectomy with fusion is recommended for RDH; however, the choice of the procedure should be made caseby- case basis, considering many factors related to the patient and surgical facilities.

Proposal of a modified tip apex distance for prediction of lag screw cut-out in trochanteric hip fractures

INTRODUCTION

Lag screw cut-out is a serious complication of dynamic hip screw fixation of trochanteric hip fractures. The lag screw position has been acknowledged as one of the important factors affecting the lag screw cut-out. We propose a modification of the Tip Apex Distance (TAD) and hypothesise that it could improve the reliability of predicting lag screws cut-out in these injuries.

MATERIALS AND METHODS

A retrospective study was conducted for hip fracture entries in the period from Jan 2018 to July 2022. A hundred and nine patients were suitable for the final analysis. The modified TAD was measured in millimetres based on the sum of the traditional TAD in the lateral view and the net value of two distances in the AP view, the first distance is from the tip of the lag screw to the opposite point on the femoral head along the axis of the lag screw while the second distance is from that point to the femoral head apex. The first distance is a positive value, whereas the second distance is positive if the lag screw is superior and negative if inferior. A receiver operating characteristic curve was used to evaluate the reliability of the different parameters assessing the lag screw position within the femoral head.

RESULTS

Reduction quality, fracture pattern as per the AO/OTA classification, TAD, Calcar Referenced TAD, Axis Blade Angle, Parker's ration in the AP view, Cleveland Zone 1, and modified TAD were statistically associated with lag screw cut-out. Among the tested parameters, the modified TAD had 90.1% sensitivity and 90.9% specificity for lag screw cut-out at a cut-off value of 25 mm with a P-value < 0.001.

CONCLUSION

The modified TAD had the highest reliability in the prediction of lag screw cut-out. A value ≤ 25 mm could potentially protect against lag screw cut-out in trochanteric hip fractures.

Finite element analysis modeling of plates versus intramedullary nails in closed comminuted midshaft tibial fractures

Background: Tibial shaft fractures are usually treated by interlocking nails or plates. The ideal implant choice depends on many variables. Aim: To assess the mechanical behavior of interlocking nails and plates in the treatment of closed comminuted midshaft fractures of the tibia using finite element analysis. Material and methods: This is a prospective study of 50 patients with a mean age of 28.4 years with closed comminuted fractures of the midshaft of the tibia. Data evaluation was done by Finite element analysis (FEA). Fixation was revised in two cases. Results: After load application, there were significant differences in both bending (P = 0.041) and strain percent (P = 0.017), reflecting that interlocking nails were superior to plates. There were also significant differences between titanium and stainless-steel materials in bending (p = 0.041) and strain percent (p = 0.017) after applying load, indicating that titanium was superior to stainless steel. Conclusion: Interlocking nails are superior to plates in treating midshaft tibial fractures. The use of blocking screws may be needed in interlocking nails depending on the pattern and extension of the fracture.

Treatment of genu valgum by a novel percutaneous transverse metaphyseal osteotomy of the distal femur in children and adolescents

PURPOSE

To evaluate the outcomes of a novel percutaneous medial supracondylar femoral osteotomy and above-knee cast technique in children and adolescents as a minimally invasive surgical intervention for treatment of genu valgum.

METHODS

In this prospective study, 60 patients (70 knees) with a tibiofemoral angle more than 15° were treated with a novel medial percutaneous supracondylar femoral osteotomy and above-knee cast and followed up for an average of 29 months. The radiological outcome was measured with MAD, TFA, and mLDFA. The functional outcome was evaluated by a modified Böstman score.

RESULTS

The preoperative mean MAD, TFA, and mLDFA were 2.9 cm, 16.3°, and 79.2° respectively. The Böstman score averaged preoperatively 23.1. There was a significant improvement of all radiological and clinical outcome measures (P < 0.001). Per Böstman score, 2 knees in one patient (3%) showed an unsatisfactory result, while 14 (20%) and 54 (77%) knees had a good or excellent result, respectively. Two patients (three limbs) needed early re-casting. Other complications were not encountered.

CONCLUSION

In experienced hands, percutaneous transverse metaphyseal femoral osteotomy and above-knee casting appear to be a safe, supracondylar cost-effective, and reliable minimally invasive acute correction technique in genu valgum in children and adolescents.

LEVEL OF EVIDENCE

Level IV-therapeutic.

The foot external rotation above-knee (FERAK) brace versus the Denis Browne brace for management of idiopathic clubfoot following Ponseti casting: a randomized controlled trial

PURPOSE

To compare the foot external rotation above-knee (FERAK) brace and the Denis Browne boot (DBB) brace in terms of relapse prevention and parents' compliance after successful correction with Ponseti casting.

METHODS

A single-centre, randomized controlled study was conducted between 2016 and 2020. A total of 60 feet in 38 patients with idiopathic clubfoot initially corrected with the Ponseti method were included. They were randomized into two equal groups: the FERAK group and the DBB group. The primary outcome was the efficacy in maintaining correction measured by the Pirani score. The secondary outcomes were parents' compliance and complications (e.g., relapses, skin complications).

RESULTS

The follow-up period was 24 months for each patient. The mean final Pirani score was 0.42 ± 0.76 in the FERAK group and 0.57 ± 0.82 in the DBB group. This difference was statistically insignificant (p-value = 0.411). Regarding parents' compliance in the FERAK group, 86.7% of parents had good and intermediate compliance while 13.3% had bad compliance. In the DBB group, 66.7% had good and intermediate compliance while 33.3% had bad compliance. This difference was also statistically insignificant (p-value = 0.118).

CONCLUSION

Both braces achieved good comparable outcomes after Ponseti casting. However, the FERAK brace yielded slightly better parents' compliance with a less recurrence rate.

Repair of spondylolysis using a pedicle screw U-shaped rod construct: A preliminary study of 25 young patients with a mean follow-up of 24 months

Study Design:

Prospective case series, therapeutic Level IV.

Objectives:

Functional and radiographic outcome evaluation of patients with spondylolysis treated with pars interarticularis defect repair with iliac bone grafting and application of a construct consisting of a pair of polyaxial pedicle screws connected by a U-shaped rod passing beneath the spinous process.

Methods:

Twenty-five patients (27 operated lumbar levels) with an average of 20 months of follow-up (range 12–24 m) with spondylolysis who met our inclusion criteria were treated with the above-mentioned technique. Functional assessment was by the Visual Analog Score (VAS) for low back pain (LBP) and Oswestry Disability Index (ODI). Fusion was confirmed with plain x-rays and when indicated with computed tomography scan. Return to activities of daily living (ADL) was also assessed.

Results:

There were 16 males (64%) and 9 females (36%), with a mean age of 18 ± 3 years at surgery, with a mean operating time of 79 ± 13 min and a mean blood loss of 186 ± 57 ml. ODI significantly improved from a mean of 63 ± 7 preoperatively to 10 ± 4 at 12 months postoperatively (P < 0.001). The mean preoperative LBP VAS score 8 ± 1 showed also a statistically significant decrease of values to 1 ± 1 at 12 months, (P < 0.001). At 12 m, all patients returned to unrestricted ADL. Pars healing was present in 19 patients (76%) at 6 months and in all patients at 12 months.

Conclusions:

Polyaxial pedicular screws with a U-shaped rod offer an effective and reproducible treatment for spondylolysis with an appropriate fusion rate, predictable return to daily activities, and good pain relief in young adults.

Evaluation of infrapatellar tendon plication in spastic cerebral palsy with crouch gait pattern: a pilot study

OBJECTIVE

In order to substantially improve crouch pattern in cerebral palsy, the existent patella alta needs to be addressed. This pilot study evaluates the effectiveness of a previously described infrapatellar tendon plication for the treatment of patella alta in crouch gait pattern in skeletally immature spastic cerebral palsy patients.

METHODS

In 10 skeletally immature patients (20 knees) with spastic diplegia and crouch gait, the previously described technique by Joseph et al. for infrapatellar tendon plication was evaluated within the setting of single event multilevel surgery (SEMLS). Outcome measures included knee extension lag, Koshino's radiological index for patella alta, and the occurrence of complications. Patients were followed-up for a minimum of 12 months.

RESULTS

The extensor lag improved and was statistically significant in all cases of the study with no incidence of tibial apophyseal injury at the latest follow-up. Radiographic Koshino index normalized and was maintained all through the follow-up period except in one patient (5%) who was overcorrected. Two patients (4 knees, 20%) showed postoperative knee stiffness due to casting which resolved with physiotherapy within six weeks. One knee (5%) developed a superficial infection which also resolved uneventfully with repeated dressings.

CONCLUSION

The described infra-patellar plication technique in skeletally immature spastic diplegics appears effective, safe, and reproducible.

Management of unstable pertrochanteric fractures, evaluation of forgotten treatment options

INTRODUCTION

Unstable trochanteric fractures are challenging with a high rate of implant failure and re-operation. Cephalomedullary nails proved to be a rational management choice for these injuries, yet other management options have not been well assessed. The aim of this study was to compare the use of DHS with trochanteric stabilizing plate (TSP) and proximal femoral locked plate (PFLP) in unstable pertrochanteric fractures.

METHODS

This randomized controlled trial (RCT) included 40 patients (22 males, 18 females) with unstable pertrochanteric fractures (AO/OTA 31A2.2/A2.3). The patients were randomized into group 1 managed by DHS with TSP while group 2 was managed by PFLP. All patients were followed up for 1 year. Patients were assessed radiographically and clinically using Harris hip score (HHS) at 3, 6 and 12 months. Operative time, estimated blood loss and time to union were also compared.

RESULTS

The difference of intra-operative variables, including operative time and intra-operative blood loss, between both groups was statistically insignificant. Time to bony union was faster in the first group with a statistically significant P value (p = 0.04). Functional outcome per HHS was significantly better in group 1 (p < 0.01) and implant failure in group 1 occurred statistically lesser (p < 0.01).

DISCUSSION

DHS with TSP appears to be a good option of management for unstable pertrochanteric fractures. In contrast, the use of PFLP in unstable pertrochanteric fractures in the elderly does not appear to be a good alternative.

Treatment of non-united femoral neck fracture by a novel subtrochanteric angulation lateral translation valgus osteotomy (SALVA osteotomy)

PURPOSE

The ideal treatment of non-united and neglected fracture neck femur in the young adult still remains unclear and is characterized by many biological and biomechanical challenges.

METHODS

Twenty-one patients with non-united or neglected fracture neck femur aged between 19 and 50 years were treated by a novel subtrochanteric valgus osteotomy and were followed up for a mean of 26.7 months. Patients were assessed by radiological parameters, the Harris Hip Score, Oxford Knee Score, and Askin Bryan Criteria to categorize the overall outcome of the patients at 24 months. Other outcome measures included the occurrence of AVN, adductor lever arm, leg length discrepancy, and mechanical implant failure.

RESULTS

All patients treated with the SALVA osteotomy consolidated and displayed a marked improvement of functional and radiological outcome measures. Nevertheless, there were 2 mechanical failures in patients with marked osteopenia and three developed AVN.

CONCLUSIONS

In patients with un-united/neglected fracture neck femur, SALVA osteotomy appears to be reliable and reproducible. It also restores the abductor lever arm and improves the leg length discrepancy. Technically less demanding conversion to arthroplasty remains still possible prospectively.

The use of platelet-rich fibrin in lumbar interbody fusion in lytic spondylolisthesis

Study Design:

This was a retrospective observational study.

Aim:

The aim of this study was to evaluate the effectiveness of applying the platelet-rich fibrin (PRF) with bone graft in accelerating the rate of lumbar interbody fusion.

Settings and Design:

This was a retrospective study measuring the outcome of posterior lumbar interbody fusion (PLIF) combined with PRF versus PLIF alone in the management of lytic spondylolisthesis.

Subjects and Methods:

Forty patients were treated with instrumented PLIF for low-grade lytic spondylolisthesis and divided into two equal groups: one with addition of PRF to the bone graft and the other without. The minimum follow-up was 2 years. Clinical outcome was measured by the Oswestry Disability Index (ODI) and Visual Analogue Pain Scale (VAS) at 3, 6, and 12 months postoperatively. Radiological outcome was measured by standing X-ray at 3, 6, 12, and 24 months and computed tomography at 6 and 12 months postoperatively.

Results:

ODI for the PRF group improved by 60% and 79% at 6 and 12 months, respectively, whereas for the non-PRF group, it improved by 55% and 70%. Radiological outcome showed fusion in 15 of 20 cases in the PRF group (75%) by the 6^th month and in 19 of 20 cases (95%) by 1 year and 100% at 2 years. In the control group, fusion was present in 12 of 20 cases (60%) by the 6^th month and in 13 of 20 cases in the PRF group (65%) by 1 year and 90% at 2 years (P < 0.05).

Conclusions:

These preliminary results show that PRF accelerates the rate of fusion in low-grade lytic spondylolisthesis in short-term follow-up.

A comparative study between the Universal Spinal System® (USS) and the CD Horizon® Legacy™ (CDH) in the management of thoracolumbar fractures

Introduction: For the treatment of unstable non-osteoporotic thoracolumbar fractures, the clinical and radiological outcome of short-segment fixation with the USS™ – Universal Spine System (DePuy Orthopedics, Inc., Warsaw, IN, USA) and the CD HORIZON^® LEGACY™ 5.5 Spinal System, (Medtronic Sofamor Danek USA, Inc., Memphis, TN, USA) were compared.

Methods: From March 2015 to January 2016, 40 consecutive patients with unstable traumatic thoracolumbar fractures who met our inclusion criteria were treated with either the USS system or CDH Legacy system. Segmental kyphosis angle (SKA) and anterior body height (ABH) of fractured vertebrae, and ASIA Impairment Scale (AIS) were evaluated. Radiological fusion was confirmed with plain X-rays and when indicated with computerized tomography (CT).

Results: The mean immediate kyphotic angle correction was 16.6° for the Schanz and 6.4 for the Legacy system, and the immediate mean anterior vertebral body height correction was 0.92 cm for the Schanz and 0.51 cm for the Legacy system. Our study shows a significant statistical difference between Schanz and Legacy systems regarding post-operative segmental kyphosis and height correction immediately postoperatively, at 6 months and at one-year follow-up (p-value < 0.005). The degree of pain reduction and neurological improvement was not influenced by the screw system.

Conclusion: Usage of USS in thoracolumbar fracture as a short-segment fixation led to a near anatomical reduction when compared to the Legacy system. However, there was no advantage regarding pain reduction and neurological outcome.

Minimally Invasive Transforaminal Lumbar Interbody Fusion for the Surgical Management of Post-Discectomy Syndrome

STUDY DESIGN

This was a prospective case series of 30 patients with post-discectomy syndrome with an average of 18 months of follow-up (level IV).

PURPOSE

The efficacy of post-discectomy syndrome managed by minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF) was evaluated.

OVERVIEW OF LITERATURE

In post-discectomy syndrome wherein conservative treatment had failed, the best surgical treatment modality still remains controversial.

METHODS

Patients were functionally assessed using the Visual Analog Scale (VAS) for low back pain (LBP) and leg pain (LP) and Oswestry Disability Index (ODI). Radiological fusion was confirmed with plain X-rays and when indicated with computed tomography scan at 12 months postoperatively. A total of 30 patients with 37 operated at lumbar levels with failed discectomy surgery who met our inclusion criteria were treated with MIS-TLIF.

RESULTS

The ODI of all patients showed significant improvement from a mean of 73.78% preoperatively to 16.67% at 1 month and 14.13% at 12 months postoperatively. The preoperative LBP VAS score (mean, 4.37) showed a significant decrease (p <0.001) to 1.90 at 1 month and 1.10 at 12 months. Preoperative LP VAS score of limb pain averaged 7.53 and showed a significant (p <0.001) decrease to 3.47 at 1 month and 1.10 at 12 months. All patients attained radiological fusion at 12 months.

CONCLUSIONS

MIS-TILF constitutes a valid and effective treatment option for patients with post-discectomy syndrome.

Effects of Polymethylmethacrylate Cement Viscosity and Bone Porosity on Cement Leakage and New Vertebral Fractures After Percutaneous Vertebroplasty: A Prospective Study

STUDY DESIGN

A prospective randomized study.

OBJECTIVES

To evaluate the effect of bone cement viscosity as well as of bone porosity on cement leakage during vertebroplasty and to analyze the occurrence of new vertebral fractures after the procedure.

METHODS

Between April 2012 and December 2013, 60 patients suffering from osteoporotic vertebral fractures underwent vertebroplasty. The patients were randomly assigned into 2 equal groups. High-viscosity cement was used in group A, while low-viscosity cement was used in group B. Patients were followed-up for a minimum of 2 years.

RESULTS

Cement leakage occurred in 16 patients in group B (20 vertebral bodies) and in 6 patients in group A (9 vertebral bodies). The difference was statistically significant (χ² = 2.3, P = .01). Lower T-scores were associated with significantly more cement leakage (t = 3.338, P = .002 in group A, and t = 4.329, P = .000 in group B). Patients with a T-score worse than -1.8 had a significantly higher risk of cement leakage if low-viscosity cement was used (χ² = 3.25, P = .05). New vertebral fractures occurred in 14 (23%) patients, after a mean of 6.5 ± 5.5 months, 10 patients in group A and 4 in group B. The difference did not reach the statistical significance level (χ² = 3.354, P = .067). Patients presenting with multiple fractures had a significantly more number of new vertebral fractures (χ² = 7.464, P = .006).

CONCLUSIONS

The clinical outcome of vertebroplasty was not influenced by cement viscosity. However, lower cement viscosity and higher degree of osteoporosis were found to be significant risk factors for cement leakage. Furthermore, the number of vertebral body fractures on presentation was a predictor for the occurrence of new fractures postoperatively.

Prevention of post-traumatic osteoarthritis after intra-articular knee fractures using hyaluronic acid: a randomized prospective pilot study

PURPOSE

Based on the irreversible destruction of hyaline cartilage, post-traumatic osteoarthritis (PTOA) is a notorious sequelae after intra-articular knee fractures. This study evaluates the clinical efficacy and applicability of immediate post-operative intra-articular injection of hyaluronic acid (IA HA) into the knee joint with an intra-articular fracture.

METHODS

Prospective randomized case-control study involving 40 patients (20 in each group) with intra-articular knee fracture with an average follow-up of 23 months (range 18-24 months). Twenty patients with intra-articular distal femoral or intra-articular proximal tibial fractures who met our inclusion criteria received three intra-articular hyaluronic acid injections weekly starting immediately after ORIF. Another 20 patients serving as a control group received no injection after ORIF. Patients were assessed functionally with Knee injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) score. Plain X-rays and when indicated CT scans were used to assess radiological union.

RESULTS

The results showed patients treated with intra-articular hyaluronic acid injection after fixation had significantly less pain (KOOS) (p = 0.01). No significant difference was found between both groups in other KOOS-related outcome measures, complications, functional outcome, or quality of life.

CONCLUSIONS

These preliminary results support a direct role for hyaluronic acid in the acute phase of the inflammatory process that follows articular injury and provides initial evidence for the efficacy of IA HA.

The use of anterior cervical interbody spacer with integrated fixation screws for management of cervical disc disease

INTRODUCTION

Integrated cage and screw designs were introduced for anterior cervical discectomy and fusion (ACDF) and allegedly are superior to anterior plating due to their minimal anterior profile.

METHODS

A descriptive study was designed as a prospective case series of 25 patients (30 operated discs) with cervical disc disease treated with a zero-profile cage, and followed up for an average of 16 months (range 12 -18 months). Functional assessment was done with the Neck Disability Index (NDI) and Visual analog scale (VAS) scores for arm and neck pain. Furthermore, Nurick's classification system for myelopathy based on gait abnormalities was documented. Radiological fusion was confirmed with plain X-rays and when indicated with a CT scan at 12 months postoperatively. Dysphagia was classified according to the Bazaz criteria.

RESULTS

VAS for neck and arm pain, NDI, and Nurick Score immediately improved postoperatively and remained so at 12-month follow-up. Fusion was achieved in 19 patients (95%) at six months and in 20 patients (100%) of the single-level group at one year. At six months 80% (four patients) and at 12 months 100% (five patients) showed complete union in the double-level group. No evidence of cage subsidence was noted radiographically.

DISCUSSION

The favorable lordosis and fusion rates of the low-profile integrated device are consistent with ACDF using anterior plating. Additionally, improved pain and an acceptable rate of dysphagia support the use of integrated interbody spacers for use in ACDF procedures.

Presentation and management of symptomatic central bone cement embolization

BACKGROUND CONTEXT

With more cement augmentation procedures done, the occurrence of serious complications is also expected to rise. Symptomatic central cement embolization is a rare but very serious complication. Moreover, the pathophysiology and treatment of intrathoracic cement embolism remain controversial.

PURPOSE

In this case series, we are trying to identify various presentations and suggest our emergent management scheme for symptomatic central cement embolization.

PATIENT SAMPLE

Retrospective case series of nine patients with symptomatic central cement embolism identified after vertebroplasty with 24 months of follow-up. Level IV.

OUTCOME MEASURES

The degree of dyspnea measured by the New York Heart Association (NYHA) score and/or death related to cement embolism induced cardio/respiratory failure at the final follow-up at 24 months.

METHODS

The nine patients, eight females, and one male had a mean age of 70.25 years (range 65-78 years) and were operated between January 2004 and December 2014. They had percutaneous vertebroplasty for osteoporotic non-traumatic and malignant vertebral collapse of dorsal and lumbar vertebrae. Post-vertebroplasty dyspnea and stitching chest pain were striking in the nine patients. After exclusion of cardiac ischemia and medical pulmonary causes for dyspnea, we identified radiopaque lesions on the chest X-ray. Further echocardiography and high-resolution chest CT were performed for optimal localization. Emergent heart surgery was performed in two patients: interventional therapy was conducted in one patient, while the remaining six patients were conservatively treated by anticoagulation. The management decision was taken in the setting of an interdisciplinary meeting depending on localization, fragmentation, and clinical status.

RESULTS

All patients of this series showed gradual improvement and an uneventful hospital stay. During our 24-month follow-up phase, eight patients showed no subsequent cardiological and/or respiratory symptoms (NYHA I). However, one mortality due to advanced malignancy occurred. Preoperative anemia was the only common intersecting preoperative parameter among these nine patients.

CONCLUSIONS

After cement augmentation, close clinical monitoring is mandatory. A chest CT is pivotal in determining the interdisciplinary management approach in view of the availability of necessary expertise, facilities and the location of the cement emboli whether accessible by cardiac or vascular surgical means. The clinical presentation and its timing may vary and the patient may be seen subsequently by other health care providers obligating a wide-spread awareness for this serious entity among health care providers for this age group as spine surgeons, family and emergency room doctors, and institutional or home-care nurses. Most symptomatic central cement emboli may be treated conservatively.

Estrogen increases affinity of oxytocin receptors in the medial preoptic area-anterior hypothalamus

Analysis of binding data from saturation experiments using a radiolabeled oxytocin antagonist ([125I]OTA) demonstrated an increase in binding affinity after treatment with 5 micrograms estradiol benzoate (EB) for 3 days in membrane fractions from the medial preoptic area-anterior hypothalamus (MPOA-AH) of ovariectomized (OVX) rats. Analysis of data from competition experiments revealed high- and low-affinity [125I]OTA binding sites in the MPOA-AH, the medial basal hypothalamus (MBH), and hippocampus of OVX controls. Three days of EB treatment reduced low-affinity binding sites in the MPOA-AH and MBH, but not in the hippocampus. Treatment of membrane fractions from the MPOA-AH of oil-treated OVX rats in vitro with 100 nM OT or with estrogen or progesterone conjugated to bovine serum albumin (E-BSA and P-BSA) also reduced low-affinity [125I]OTA binding sites but BSA alone did not.

Oxytocin selectively increases holding and licking of neonates in preweanling but not postweanling juvenile rats

Preweanling rats exhibit components of maternal behavior (MB) after brief periods of contact with neonates; the latency of onset of MB rises considerably after weaning. Oxytocin (OXT) stimulates MB in adult rats. The effects of intracisternal (IC) administration of OXT (2 micrograms) on pup-directed and other behaviors in preweanling and postweanling juvenile rats were tested. Compared with saline and no treatment, OXT significantly increased active holding of pups in preweanling but not postweanling juvenile rats. No other components of adultlike MB were stimulated by OXT. OXT also decreased inactive touching of pups and robustly increased selfgrooming in juveniles at all ages tested. It is concluded that OXT facilitation of active pup-holding and licking in preweanling rats may be an extension of OXT-induced self-grooming to pups and may also be related to OXT activation of MB in adult rats.

Oxytocin selectively increases holding and licking of neonates in preweanling but not postweanling juvenile rats

Preweanling rats exhibit components of maternal behavior (MB) after brief periods of contact with neonates; the latency of onset of MB rises considerably after weaning. Oxytocin (OXT) stimulates MB in adult rats. The effects of intracisternal (IC) administration of OXT (2 micrograms) on pup-directed and other behaviors in preweanling and postweanling juvenile rats were tested. Compared with saline and no treatment, OXT significantly increased active holding of pups in preweanling but not postweanling juvenile rats. No other components of adultlike MB were stimulated by OXT. OXT also decreased inactive touching of pups and robustly increased selfgrooming in juveniles at all ages tested. It is concluded that OXT facilitation of active pup-holding and licking in preweanling rats may be an extension of OXT-induced self-grooming to pups and may also be related to OXT activation of MB in adult rats.

A uterotonic antagonist blocks the oxytocin-induced facilitation of female sexual receptivity

The nonapeptide oxytocin (OXT) has been shown to facilitate female sexual receptivity when infused into the cerebral ventricles or the basal forebrain. Various selective antagonists have been used to block other behavioral effects of centrally administered OXT. In this study we compared the effects of equal doses of uterotonic, antidiuretic (V2) or vasopressor (V1) antagonists in blocking the facilitative effects of a simultaneous infusion of OXT into the basal forebrain. Ovariectomized (OVXed) animals were implanted with chronic cannulas in the basal forebrain. All animals were then given 0.5 micrograms estradiol benzoate daily for 3 days before testing. On the fourth day animals were tested to 8-10 mounts with a sexually vigorous male before and 20, 40 and 90 min after infusions of 500 ng OXT alone or in combination with a uterotonic, V2 or a V1 antagonist analogue. OXT significantly increased lordosis responding 20 and 40 min after its infusion into the medial preoptic area and anterior hypothalamus when compared to the receptivity of normal saline vehicle infused animals. The uterotonic antagonist significantly blocked the facilitation seen after OXT. The V1 and V2 antagonists at equal doses had no effect on the OXT-induced facilitation of lordosis postures. The V1 antagonist itself facilitated sexual receptivity 90 min after infusion. The facilitative effect of OXT on receptivity appears to be mediated by central uterotonic receptors, while central vasopressor receptors may serve an inhibitory role.

Estrogen alters oxytocin mRNA levels in the preoptic area

Abstract Estrogen has numerous effects on immunoreactive levels of oxytocin (OXT) centrally, particularly in the preoptic lateral subcommissural nucleus (LSN). In this study in situ hybridization of a 38-base oligodeoxyribonucleotide (38mer) complementary to OXT mRNA revealed that estrogen treatment altered the pattern of OXT production in the rostral LSN and the more caudal anterior commissural nucleus. Rats were injected with 20 ng estradiol benzoate or sesame oil vehicle im 4 and 5 days after ovariectomy. On the sixth day all animals were perfused with paraformaldehyde-glutaraldehyde and their brains sectioned to 10 mum thickness in a -10 degrees C cryostat. Coronal brain sections were taken from four parallel levels of the preoptic-anterior hypothalamic area. These sections were mounted and hybridized in situ to a [l(125)]-labeled 38mer for 16 h at 37 degrees C. Washed and dried slides were processed for autoradiography and analyzed with a light microscope. The effect of estrogen on OXT production differed between the rostral and caudal sections in both the LSN and periventricular (PeV) areas. Estrogen significantly increased OXT mRNA levels in LSN cells while decreasing hybridization in the anterior commissural nucleus cells. Changes in frequency patterns in the PeV paralleled those in the LSN with a significant drop of hybridization in the caudal PeV. Neurons hybridizing 38mer probe were also found in several other areas including the ventral medial preoptic area, lateral hypothalamus, bed nucleus of the stria terminalis and the nucleus triangularis septi. OXT mRNA levels were affected by estrogen treatments and this effect differed between the preoptic area and anterior hypothalamus. The sensitivity of LSN oxytocinergic cells to estrogen has implications for estrogen-sensitive OXT-enhanced reproductive behaviors.