Spinal organization and steroid sensitivity of motoneurons innervating the pubococcygeus muscle in the male rat.

Male rat motoneurons innervating the pubococcygeus muscle were located in the ventral nucleus of lamina IX at the sixth lumbar (L6) and first sacral (S1) spinal cord segments. Retrograde labeling with horseradish peroxidase-wheat germ agglutinin was transported up to second-order dendrites and revealed that these motoneurons have a "U-shaped arborization" of dendrites toward the intermediolateral and intermediomedial nuclei area of lamina VII. This dendritic organization makes a wide "final common path" that probably integrates afferent information from several sources, accounting for the participation of the pubococcygeus muscle in autonomic and somatic processes, such as those related to micturition and reproduction. Castration produced a decrement in the morphometry of these motoneurons. A main effect was a decrement in dendritic length. Steroid replacement indicated that testosterone and estradiol, but not dihydrotestosterone, are able to induce a recovery of morphometric alterations. However, estrogen induced recovery after 2 weeks of treatment, whereas testosterone took 4 weeks. Thus, it is proposed that supraspinal aromatization of testosterone in the male central nervous system might be an important process for the appropriate organization of the pubococcygeus muscle motoneurons and that estradiol seems to need a shorter time of action than testosterone because of differential up-regulation and down-regulation of steroid receptors.     

Medial prefrontal transection enhances social interaction. II: neurochemical studies

Medial prefrontal cortex (MPFC) transection enhances social interaction in an open arena test. Social interaction enhances dopaminergic activity in the nucleus accumbens (NAC). In the present set of experiments, microdialysis probes were implanted in the NAC, and glutamate, gamma-aminobutyric acid (GABA) and dopamine (DA) were measured during electrical stimulation of the MPFC, after coronal transection caudal to the MPFC and after a systemic injection of amphetamine in transected rats. Electrical stimulation of the MPFC caused a transient enhancement of glutamate release in the NAC, no change in GABA levels and a long lasting increase in DA levels. Medial prefrontal transection did not change basal glutamate or GABA levels in the NAC, but increased basal DA levels. Amphetamine administration decreased GABA levels in medial prefrontal transected rats, had no effect on glutamate and increased DA levels more than in controls. The experiments suggest that glutamatergic activity in the accumbens decreases dopamine release. Medial prefrontal transection reduces glutamatergic tone and enhances dopamine release, which probably decreases GABAergic activity in the NAC. Presumably, GABA inhibition in the NAC enhances social interaction.     

Distribution of protein kinase Mzeta and the complete protein kinase C isoform family in rat brain

Protein kinase C (PKC) is a multigene family of at least ten isoforms, nine of which are expressed in brain (alpha, betaI, betaII, gamma, delta, straightepsilon, eta, zeta, iota/lambda). Our previous studies have shown that many of these PKCs participate in synaptic plasticity in the CA1 region of the hippocampus. Multiple isoforms are transiently activated in the induction phase of long-term potentiation (LTP). In contrast, a single species, zeta, is persistently activated during the maintenance phase of LTP through the formation of an independent, constitutively active catalytic domain, protein kinase Mzeta (PKMzeta). In this study, we used immunoblot and immunocytochemical techniques with isoform-specific antisera to examine the distribution of the complete family of PKC isozymes and PKMzeta in rat brain. Each form of PKC showed a widespread distribution in the brain with a distinct regional pattern of high and low levels of expression. PKMzeta, the predominant form of PKM in brain, had high levels in hippocampus, frontal and occipital cortex, striatum, and hypothalamus. In the hippocampus, each isoform was expressed in a characteristic pattern, with zeta prominent in the CA1 stratum radiatum. These results suggest that the compartmentalization of PKC isoforms in neurons may contribute to their function, with the location of PKMzeta prominent in areas notable for long-term synaptic plasticity.     

Extracellular matrix of the human lamina cribrosa

We used immunoperoxidase staining and double immunofluorescent staining to demonstrate the macromolecular components of the extracellular matrix of the lamina cribrosa from young human donors. The cribriform plates were made up of a core of elastin fibers with a sparse, patchy distribution of collagen type III. The plates were coated with collagen type IV and laminin; these basement membrane components were presumably made by the astrocytes that were distributed on the surfaces of the plates. The insertion of the lamina cribrosa in the sclera was made up of concentric, circumferential elastin fibers that surrounded the lamina cribrosa and were continuous with the elastin in the cribriform plates. Astrocytic processes extended into the bundles of elastin fibers, whereas the basement membrane components extended into the sclera. The mechanical properties of the macromolecules of the extracellular matrix of the lamina cribrosa may make this tissue compliant and sensitive to intraocular pressure. Perhaps individual differences in the macromolecular components of this tissue contribute to the glaucomatous changes in the optic nerve head.     

Results of the national survey of borderline ovarian tumors in Spain

MATERIAL AND METHODS: Retrospective multi-center analysis of women diagnosed with borderline ovarian tumor and treated between January 1990 and December 1997. A national survey was conducted, in which 457 patients from 27 centers corresponding to ten of Spain's autonomous communities were analyzed. RESULTS: Four hundred fifty-seven women with borderline ovarian tumor were analyzed. The mean age of patients was 45.5+/-16.9 years. Of these, 390 patients (85.3%) were at stage I, 8 (1.8%) were at stage II and 36 (7.9%) at stage III. A bilateral tumor was observed in 63 women (13.8%). The mean tumor size was 14.2 cm and in 88 cases (19.3%) the tumor was on the surface of the ovary. Microinvasion was observed in 25 (5.5%) cases, and 29 women (6.3%) showed a micropapillary pattern. Study of the factors related to the appearance of peritoneal implants revealed positive tumor markers (OR 15.02: 1.9-32.9) and a tumor on the ovarian surface (OR 8.0: 1.8-127) to be independent risk factors. With respect to recurrence, the presence of peritoneal implants at the time of initial surgery (OR 3.4: 1.1-10.4) and signs of microinvasion in the anatomicopathological study (OR 5.5: 1.5-17.8) were found to be independent risk factors. The overall survival rate in our series was 97% with a mean follow-up of 88.3 months. The survival rate by stage was 97% for stage I, 100% for stage II and 97% for stage III. CONCLUSIONS: Although borderline ovarian tumors have an excellent prognosis, they are not exempt from a risk of recurrence. Characterization of patients with borderline ovarian tumor is essential in order to prevent their evolution. Likewise, the taking on board of risk factors will enable more selective treatments to be offered in each case.