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Ischaemic post-conditioning (IPostC) might represent an innovative surgical approach to protect organs from ischaemia and reperfusion (I/R) injury. We investigated the molecular mechanisms underlying the contrasting effects of IPostC on the early and late damage induced by testicular I/R injury. Testis I/R was induced by occluding the right testicular vessels using a clip. Male rats were divided into the following groups: sham, I/R and I/R + IPostC. In the I/R group, the clip was removed after 60 min of ischaemia, and reperfusion was allowed for 30 min, 1 and 30 days. In the I/R + IPostC group, three cycles of 30-sec reperfusion and 30-sec ischaemia were performed after 60 min of ischaemia and then reperfusion followed up for 30 min, 1 and 30 days. Following 30-min reperfusion, there was an increase in mitogen-activated protein kinases (MAPKs) in I/R rats; after 1 day of reperfusion, interleukin-6, tumour necrosis factor-α and nuclear factor-κB (NF-κB) expression were significantly increased; IκB-α expression reduced; and a marked damage in both testes was observed. IPostC inhibited MAPKs, cytokines and NF-κB expression, augmented IκB-α expression and decreased histological damage in testes subjected to I/R. After 30 days of reperfusion, I/R injury activated the apoptosis machinery, caused severe histological damage and reduced spermatogenic activity. By contrast, IPostC did not modify the apoptotic markers, the histological alterations as well as spermatogenic activity following 30 days of reperfusion. Our data demonstrate that IPostC protects the testis from the early damage induced by I/R injury, but it does not protect against the late damage., (© 2013 American Society of Andrology and European Academy of Andrology.)

To determine human papillomavirus (HPV) types distribution in cervical lesions in a Southern Italian female population in Messina and their relationship between HPV type and grade of colposcopic and histopathological abnormality, a total of 253 women aged 17-68 years, with previous cytological abnormalities, were included in this study. HPV-DNA testing, colposcopy and biopsy were performed. For each sample, cervical cells were collected by centrifugation and DNA was extracted, followed by a PCR-based HPV-DNA assay and reverse dot blot genotyping. HPV-16 was found the most common type (46.6 %) followed by HPV-31 (26.9 %), -6 (18.6 %), -58 (8.8 %), -18 (6.7 %), -66 (5.7 %), -52 and -53 (4.7 %). Out of 62 women with abnormal transformation zone (ATZ) area compatible with squamous intraepithelial lesion (SIL) or cervical cancer (CC), 64.5 % was found high risk (HR) HPV-positive. Moreover the severity of the colposcopic diagnosis was positively correlated with the higher HPV oncogenicity risk (HPV-16 P = 0.023; and HPV-53 P = 0.047). The HPV-16 was found the most prevalent type within each histological category: 66.7 %, 31.2 %, 44 % and 37.2 % of CC, high grade (H)SIL, low grade (L)SIL and chronic cervicitis respectively; followed by HPV-31 present in 25 %, 8 %, and 13.3 % of HSIL, LSIL and chronic cervicitis respectively. A higher HPV incidence than the rest of Italy was found, in agreement with that detected by other authors for the South of the country. These data provide further information about the types prevalence in women with cervical lesions living in Eastern Sicily, suggesting the introduction of new targeted vaccines against a wider spectrum of HPV.

Background: Pacemakers in upper urinary tract (UUT) are still under study., Aim: We reviewed the role of some cells that seem to be involved in the propulsion of urinary bolus from UUT to the bladder., Materials & Methods: We focuses on evaluating studies on the mechanisms by which the UUT propels urine to the bladder via pacemaker cells., Results: Electric active pacemaker cells generate pyeloureteric autorhythmicity driving adjacent smooth muscle cells (SMCs); it emphasizes the role of the interstitial cells of Cajal-like cells (ICC-LCs) localized in the UUT. Interstitial cells of Cajal (ICCs) are now thought to cooperate in conducting and amplifying pacemaker activity in the UUT. These cells produce electrical slow-wave potentials and determine the propagation of peristaltic activity. Identification of ICC-LCs is facilitated by use of c-kit antibodies. Contraction waves arising from the UUT and the propagation of these waves may require the direct involvement of ICC-LCs, as c-kit immunoreactivity appears developmentally at the same time as coordinated unidirectional peristaltic contraction. ICC-LCs observed in the UUT have morphological features similar to those of c-kitpositive ICCs in the gastrointestinal tract. In addition to gastrointestinal motility, ICCs may also play a significant role in the propagation, coordination, and modulation of ureteropelvic peristalsis., Discussion: Alterations in ICC-LCs are closely associated with a variety of motility disorders and many congenital urological diseases of the UUT such as primary obstructive megaureter, congenital ureteropelvic junction obstruction, and vesicoureteral reflux., Conclusion: These observations open the way for further investigations of this cell type., (Copyright © 2012 Wiley Periodicals, Inc.)

The effects of polydeoxyribonucleotide (PDRN), an agonist of the A2A adenosine receptors which when activated positively influences sperm activity, were tested in an experimental testicular ischaemia/reperfusion injury model. Anaesthetized male Sprague-Dawley rats were subjected to testicular torsion-induced ischaemia, followed by reperfusion (TI/R). Immediately after detorsion, randomized animals, including SHAM, received intraperitoneal injections of: (i) vehicle (1 mL/kg 0.9% NaCl solution); (ii) PDRN (8 mg/kg); (iii) DMPX (3,7-dimethyl-1-propargilxanthine, 0.1 mg/kg); or (iv) PDRN (8 mg/kg) + DMPX (0.1 mg/kg). Animals were euthanized at 1, 7 and 30 days following reperfusion. Vascular endothelial growth factor (VEGF) expression is normally associated with adenosine A2A receptor stimulation. After treatment, VEGF mRNA/protein expression quantified by qPCR and Western blot, vascular endothelial growth factor receptor-1 (VEGFR1) and endothelial nitric oxide synthase (eNOS) mRNA measured by qPCR, VEGF and VEGFR1 assessed using immunohistochemical methods, histological staining and spermatogenic activity were all analysed. Testis ischaemia-reperfusion (TI/R) injury caused increases in VEGF mRNA and protein, VEGFR1 and eNOS mRNA, histological damage and reduced spermatogenic activity. Immunostaining showed a lower expression of VEGF in germinal epithelial cells and a strong expression of VEGFR1 in Leydig cells after TI/R. PDRN administration increased significantly VEGF message/protein, VEGFR1 and eNOS message, decreased histological damage and ameliorated spermatogenic activity. PDRN might be useful in the management of testicular torsion., (© 2011 The Authors. International Journal of Andrology © 2011 European Academy of Andrology.)

Objective: To study the effect of PDRN on angiogenesis in a model of varicocele in rats., Design: After the creation of experimental varicocele, rats were randomized to one of the four treatments: vehicle, PDRN, DMPX, and PDRN plus DMPX. Twenty-one days after randomization, all animals were euthanized and the left testis was harvested., Setting: Academic hospital., Animal(s): Male Sprague-Dawley rats were used., Intervention(s): A clamp was passed behind the left renal vein distally to the spermatic vein insertion. A silk ligature was placed around the left renal vein at this site and was tied over the top of a probe. The latter was then withdrawn and the vein was allowed to expand. In shams, a suture was placed but it was not tied., Main Outcome Measure(s): To assess testicular microvascular density using CD34 immunostaining., Result(s): Microvascular density in the varicocele plus PDRN group was significantly higher than in other groups., Conclusion(s): PDRN could represent a novel therapeutic strategy for varicocele treatment in subfertile patients, improving the innate pathophysiologic mechanism of neoangiogenesis, through compensatory oxygen and metabolite supply to tubular and extratubular testicular compartments., (Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Melanocortins (MC) trigger a vagus nerve-mediated cholinergic-antiinflammatory pathway projecting to the testis. We tested whether pharmacological activation of brain MC receptors might protect the testis from the damage induced by ischemia-reperfusion. Adult male rats were subjected to 1-h testicular ischemia, followed by 24-h reperfusion [testicular ischemia-reperfusion (TI/R)]. Before TI/R, groups of animals were subjected to bilateral cervical vagotomy, or pretreated with the nicotinic acetylcholine receptor antagonist chlorisondamine or the selective MC(4) receptor antagonist HS024. Immediately after reperfusion, rats were ip treated with saline or the MC analog [Nle(4),D-Phe(7)]α-melanocyte-stimulating hormone (NDP-α-MSH) (340 μg/kg). We evaluated testicular IL-6 and TNF-α by Western blot analysis and organ damage by light microscopy. Some experimental groups were prepared for neural efferent activity recording along the vagus nerve starting 30 min after treatment with NDP-α-MSH or saline, and for a 30-min period. Additional groups of TI/R rats were treated for 30 d with saline, NDP-α-MSH, chlorisondamine plus NDP-α-MSH, or HS024 plus NDP-α-MSH to evaluate spermatogenesis, organ damage, and the apoptosis machinery. After a 24-h reperfusion, in TI/R saline-treated rats, there was an increase in IL-6 and TNF-α expression and a marked damage in both testes. NDP-α-MSH inhibited IL-6 and TNF-α expression, decreased histological damage, and increased neural efferent activity. Furthermore, NDP-α-MSH administration for 30 d greatly improved spermatogenesis, reduced organ damage, and inhibited apoptosis. All positive NDP-α-MSH effects were abrogated by vagotomy, chlorisondamine, or HS024. Our data suggest that selective MC(4) receptor agonists might be therapeutic candidates for the management of testicular torsion.

Objective: Acute pancreatitis is an inflammatory condition that may lead to multisystemic organ failure. Melanocortin peptides have been successfully used in experimental models of organ failure and shock, and their protective effect occurs through the activation of a vagus nerve-mediated cholinergic anti-inflammatory pathway by acting at brain melanocortin 4 receptors. In the light of these observations, we studied the effects of the selective melanocortin 4 receptor agonist RO27-3225 in an experimental model of cerulein-induced pancreatitis., Design: Randomized experiment., Setting: Research laboratory at a university hospital., Subject: Experimental pancreatitis in rats., Interventions: Acute pancreatitis was induced in male Sprague-Dawley rats by intraperitoneal injections of cerulein (80 μg/kg, four injections at hourly intervals). Before pancreatitis induction, groups of animals were subjected to bilateral cervical vagotomy, pretreated with the nicotinic acetylcholine receptor antagonist chlorisondamine or the selective melanocortin 4 receptor antagonist HS024, or not pretreated. Thirty minutes after the first cerulein injection, rats were intraperitoneally treated with a nanomolar dose of RO27-3225 or vehicle. Some experimental groups were prepared for neural efferent activity recording along the vagus nerve starting 30 mins after treatment with RO27-3225 or vehicle, and for a 30-min period., Measurements and Main Results: Serum lipase and amylase activity, tumor necrosis factor-α and interleukin-6 expression, pancreatic myeloperoxidase activity, and histologic damage were evaluated; neural efferent activity of vagal fibers was also assessed. RO27-3225 reduced cerulein-induced serum lipase and amylase activity, blunted the expression of tumor necrosis factor-α and interleukin-6, abated the increase in pancreatic myeloperoxidase activity, and protected against histologic damage. Furthermore, RO27-3225 markedly increased neural efferent activity along the vagus nerve. Vagotomy, chlorisondamine, and HS024 abated these protective effects of RO27-3225., Conclusions: Our data show that melanocortin 4 receptor agonists reduce pancreatitis severity through the activation of the cholinergic anti-inflammatory pathway. These findings could be of particular interest in the clinical setting.

In rat experimental varicocele, polydeoxyribonucleotide (PDRN) induces vascular endothelial growth factor (VEGF) production, thereby enhancing testicular function. This may point to a new therapeutic approach in human varicocele., (Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: Endometrial hyperplasia without cytological atypia is commonly treated with progestins, but other treatment regimes may be available with equivalent efficacy and low side effects., Design: A randomized double-blind, placebo and progesterone-controlled clinical trial to evaluate the effects of genistein aglycone in reducing endometrial hyperplasia., Patients: A group of 56 premenopausal women with non-atypical endometrial hyperplasia were enrolled and received: genistein aglycone (n=19; 54 mg/day); norethisterone acetate (n=19; 10 mg/day on days 16-25 of the menstrual cycle) or placebo (n=18) for 6 months., Measurements: Hysteroscopy was performed with biopsies and symptomology assessed at baseline, 3 and 6 months of administration. The effect on estrogen (ER) and progesterone receptors (PR) expression in uterine biopsies were assessed after 3 and 6 months. For each treatment follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), sex hormone-binding globulin (SHBG) and progesterone (PG) levels were also evaluated., Results: After 6 months, 42% of genistein aglycone-administered subjects had a significant improvement of symptoms (histologically confirmed in the 29%) compared to 47% of norethisterone acetate subjects (histologically confirmed in the 31%), but only 12% in the placebo group with 19% exhibiting worsening symptoms and increased endometrial thickness. No significant differences were noted for hormone levels for any treatment, but immunohistochemical analysis revealed significantly reduced staining for ER-alpha and PR and enhanced ER-beta1 staining in genistein-administered subjects associated with a complete regression of bleeding., Conclusions: These results suggest that genistein aglycone might be useful for the management of endometrial hyperplasia without atypia in women that cannot be treated with progestin., (Copyright 2010 Elsevier GmbH. All rights reserved.)

Purpose: Testicular torsion is a medical emergency that requires immediate diagnosis and treatment to avoid subsequent testicular injury and infertility. PPARs are a family of nuclear hormone receptors belonging to the steroid receptor superfamily. Three PPAR isotypes (alpha, beta/delta and gamma) encoded by separate genes and showing different tissue distribution patterns have been identified. PPARbeta/delta is expressed in testis and its role is largely unknown. We tested whether pharmacological activation of PPARbeta/delta might protect the testis from ischemia and reperfusion injury., Materials and Methods: Adult male Sprague-Dawley rats were subjected to 1-hour testicular ischemia, followed by 24 hours of reperfusion. Sham testicular ischemia-reperfusion rats served as controls. The animals were randomized to receive immediately after detorsion 1) L-165,041 (4 mg/kg intraperitoneally), a potent agonist of PPARbeta/delta, 2) GW9662 (Calbiochem(R)) (4 mg/kg intraperitoneally), an antagonist of PPAR, 3) L-165,041 (4 mg/kg intraperitoneally) plus GW9662 (4 mg/kg intraperitoneally) concomitantly or 4) vehicle (1 ml/kg 10% dimethyl sulfoxide/NaCl solution). We evaluated testicular extracellular signal regulated kinase, tumor necrosis factor-alpha and interleukin-6 by Western blot. We also investigated PPARbeta/delta activation by Western blot, mRNA expression and organ damage., Results: Testicular ischemia-reperfusion injury caused a significant increase in extracellular signal regulated kinase, tumor necrosis factor-alpha and interleukin-6 expression in each testis. Furthermore, histological examination revealed marked damage. L-165,041 administration increased the PPARbeta/delta message and protein, inhibited extracellular signal regulated kinase, tumor necrosis factor-alpha and interleukin-6 expression, and decreased histological damage. Concomitant administration of GW9662 reversed the protection exerted by PPARbeta/delta agonist., Conclusions: These findings indicate that PPARbeta/delta agonists might be an attractive therapeutic candidate for managing testicular torsion.

Nuclear factor kappa-B (NF-kappaB), mitogen-activated protein kinase3/MAPK1 and MAPK8 are involved in testicular ischemia reperfusion injury (testicular-I/R). NF-kappaB knock-out mice (KO) subjected to testicular-I/R have a reduced testicular damage, blunted MAPK8 activation and enhanced MAPK3/MAPK1 activity. To better understand the role of MAPK3/MAPK1 up-regulation during testicular-I/R, we investigated the effects of PD98059, an inhibitor of MAPK3/MAPK1, in KO mice during testicular-I/R. KO and wild-type (WT) animals underwent 1 h testicular ischemia followed by 24 h reperfusion or a sham testicular-I/R. Animals received either PD98059 (5 mg/kg/ip) or its vehicle. MAPK3/MAPK1, BAX, caspase-3 and -9 and TNF-alpha expression were assessed along with histological examination and an immunostaining for protein of apoptosis. Testicular-I/R caused a greater increase in MAPK3/MAPK1 in KO than in WT animals in both testes. KO mice had a lower expression of the apoptotic proteins and TNF-alpha as well as reduced histological damage compared to WT. Immunostaining confirmed the lower expression of BAX in the Leydig cells of KO mice. Administration of PD98059, abrogated MAPK3/MAPK1 expression and slightly reduced TNF-alpha but did not improve or reverse the histological damage in KO. PD98059 significantly reduced the histological damage in WT mice and markedly reduced the apoptotic proteins in KO and WT mice. These results suggest that testicular-I/R triggers also a pathway of organ damage involving MAPK3/MAPK1, TNF-alpha, BAX, caspase-3 and -9 that activates an apoptotic machinery in an NF-kappaB independent manner. These findings should contribute to better understand testicular torsion-induced damage.

Neonatal hemochromatosis is a rare congenital disorder of the liver associated to a poor prognosis. Liver transplantation is often required, since no effective medical treatment has been found. Despite mounting evidence of an alloimmune etiology of this condition, exchange transfusion has never been proposed as a specific treatment for neonatal hemochromatosis. Here we describe two siblings affected by neonatal hemochromatosis. The first, a female, died at 18 days of severe coagulopathy and acute renal failure, diagnosed as affected by neonatal hemochromatosis only when the second sibling was suspected as being affected by the same disease. The second child showed a rapidly worsening coagulopathy which was treated with two exchange transfusions, followed by rapid clinical and laboratory improvement, before reaching a definite diagnosis of neonatal hemochromatosis. He is healthy at present after a follow-up of 12 months. Although exchange transfusion has never been considered as treatment for neonatal hemochromatosis, this case suggests that it could be a feasible treatment option for children affected by this disease, as for other alloimmune conditions.

Nuclear factor kappa-B (NF-kappaB), extracellular regulated kinase (ERK 1/2) and c-jun-N terminal kinase (JNK) play an important role in testicular ischemia. We investigated the patterns of ERK1/2, JNK and p38 activation in NF-kappaB knockout (KO) mice subjected to testicular torsion. KO and normal littermate wild-type (WT) animals underwent at 1 h testicular ischemia followed by 24 h reperfusion (TI/R). Sham testicular ischemia-reperfusion mice served as controls. ERK 1/2, JNK and p38 expression by western blot analysis, tumor necrosis factor-alpha (TNF-alpha) expression (RT-PCR and western blot analysis) and a complete histological examination were carried out. TI/R caused a greater increase in phosphorylated form of ERK 1/2 in KO mice than in WT animals in either the ischemic testis and the contralateral one. By contrary, active form of JNK and p38 were completely abrogated in both testes of KO mice, while WT animals showed a significant activation of those kinases in both testes. TNF-alpha expression was markedly reduced in KO mice when compared to WT mice either at the mRNA and the protein level. Finally TI/R-induced histological damage was markedly reduced in KO mice. Our data indicate that NF-kappaB plays a pivotal role in the development of testicular ischemia-reperfusion injury and suggest that, in the absence of the transcriptional factor, the up-stream signal JNK and p38 may be abrogated while ERK 1/2 activity is enhanced.

Purpose of Investigation: Retrospective evaluation of hysteroscopic findings in the accurate diagnosis of endometrial carcinoma., Methods: A retrospective monocentric study from January 1995 to December 2004. One hundred and four patients with hysteroscopic aspects evocative of endometrial carcinoma confirmed by endometrial biopsy during diagnostic hysteroscopy, by surgical hysteroscopic resection pieces or by hysterectomy specimen were included., Results: Among the 104 patients, diagnostic hysteroscopy pointed out endometrial features suggestive of endometrial carcinoma in 102 cases. In two women diagnostic hysteroscopy failed to diagnose endometrial malignancy which was identified on pieces of polyps by surgical hysteroscopic resection., Discussion: Polypoid proliferations cerebroid in appearance, with ulceration and necrosis, friable and with irregular vessels, represent endometrial findings highly indicative of malignancy. The diagnosis may be missed in cases of focal neoplasias, within endometrial polyps or in conditions of unsatisfactory endouterine visualization.

Vaginal submucosal nodules were observed in a 67-year-old woman, with ultrasonographic features of an advanced uterine neoplasm. On biopsy, light microscopy suggested that the lesions might be metastatic foci from an extragenital cancer, with a prevalent tubular growth pattern. Parallel immunohistochemical reactions revealed a diffuse, strong CA 19-9 positivity in both the cell membrane and cytoplasm. Subsequently, high serum levels of such tumor marker were also found, and an extragenital cancer was suspected of pancreatic or biliary origin. A mass in the gallbladder fossa was then detected by computed tomography and a primary gallbladder adenocarcinoma was confirmed on ultrasound-guided biopsy.

The aim of this study was to review the histology of the upper pole segment in patients with duplex ectopic ureterocele to verify if a less aggressive surgery is justified in the prenatally diagnosed patients. We reviewed the histology of the upper pole segment of 15 consecutive patients with duplex system ectopic ureterocele treated between 1991 and 1999 at the Paediatric Surgery Unit of University Hospital of Messina. The diagnosis of duplex system ectopic ureterocele was made according to the criteria of the Section on Urology of the American Academy of Paediatrics. The histology specimens were assessed for dysplastic, inflammatory and obstructive changes. All 15 patients with duplex system ectopic ureterocele were surgically treated with heminephro-ureterectomy and the surgical specimens were histologically examined. Nine of the 15 patients were prenatally diagnosed. The histology of the upper pole segment of the 9 prenatally diagnosed showed in all patients segmental renal microcystic dysplasia, chondroid metaplasic islands and an inflammatory tubulo-interstitial nephropathy in 6 patients (66.6%) and in 2 (22.2%) nephroblastomatosis. The histology of six the postnatal postnatally diagnosed patients showed in all patients segmental multicystic renal dysplasia, inflammatory tubulo-interstitial nephropathy and segmental parenchymal scars. The upper pole histology of the patients with duplex ectopic ureterocele diagnosed prenatally did not show any evidence of reversible histological change. Considering the histology and the good outcome of patients treated with upper pole nephroureterectomy a less aggressive surgery with preservation of the upper pole does not seem justified.

Objective: To examine the maturational-delay hypothesis of primary megaureter (PM), i.e. that the condition arises by a segmental maturational delay of the ureteric wall that can resolve spontaneously within the first year of life, using comparative immunocytochemistry of ureters resected from infants and from homologous pre-natal ureters., Materials and Methods: Seventeen distal urinary tracts were obtained from children with PM who were referred for surgery (aged 6 months to 8 years, mean 2.1 years). These were compared with ureteric buds obtained from 11-week-old human and 11- to 38-week-old calf fetuses. The samples were immunostained using a monoclonal antibody specific for transforming growth factor beta (TGF-beta)., Results: The histological appearances of the narrowed ureteric segments from patients under 18 months old were like the fetal ureteric buds at 26-38 weeks of gestation. Positive TGF-beta immunoreactions were detected in the longitudinal muscle layer in the ureter from patients 6-12 months old. Such reactions weakened progressively in those patients older than 1 year, becoming negative in all children older than 3 years. The TGF-beta immunolabelling in resected ureters was closely similar to that in fetal ureters from 20 to 26-week old calves., Conclusions: From these results, PM should be ascribed to a segmental developmental delay of the terminal ureter arising at about 20 weeks of gestation, with a possible pathogenetic involvement of autocrine TGF-beta overexpression.

Some cytochemical and immunocytochemical investigations were carried out on actively growing Yoshida ascites sarcoma cells. These cells displayed an intense granular alpha-naphthylacetate esterase (ANAE) staining while the alpha-naphthylbutyrate esterase (ANBE) reaction was in part fluoride-sensitive and marked particularly in the large-size malignant cells. Acid phosphatase as well as peroxidase activities were not detected. The lack of immunoreactive lysozyme and alpha 1-antitrypsin suggested a poor differentiation of the above-mentioned tumor cells, but fibronectin and S-100 protein where highly expressed, as in tumors arising from the mononuclear phagocyte system.

The effects of subcutaneous daily treatment with thyroxine on cell proliferation, differentiation, polyamines, and gamma-aminobutyric acid metabolism in the rat retina were studied during the first 20 postnatal days. The retinal layers of the treated rats displayed an enhanced cell differentiation which reached its maximum 9-12 days from birth; but this effect stopped very quickly and was finished by the 20th postnatal day. Primarily there was an increase in ornithine decarboxylase activity which was accompanied by an increase in putrescine, spermidine, and spermine levels. S-Adenosylmethionine decarboxylase was induced later than ODC; corresponding with the enhanced synaptogenesis, glutamate decarboxylase increased 15-fold between the fourth and 15th days. Our data are consistent with the hypothesis that thyroxine may exert some of its effects by inducing the enzymes which regulate polyamine metabolism and synaptogenesis.