Physical, histological, endocrinological and steroidogenical evaluation of male cats postnatally exposed to sexual steroids.

To test the hypothesis that postnatal sexual steroids induce an impairment of domestic male cat reproductive function, this study describes the physical, endocrine, steroidogenical and histological effects of a single, high dose of a postnatal sexual steroid in this species. Twenty male kittens were randomly assigned within the first 24 h of birth to: Testosterone enanthate 12.5 mg sc (TE; n = 8), medroxyprogesterone acetate 10 mg sc (MA; n = 6), or Placebo sc (PL; n = 6). The cats were followed until puberty when they were castrated. Kittens achieved puberty without age differences among groups (P > 0.05). Two MA cats presented abnormal testicular descent. Histological evaluation of the MA (P < 0.01), but not of TE testes revealed decreased diameter (P < 0.01) and epithelial height (P < 0.01) of the seminiferous tubules. Leydig cell nuclear area was also reduced in this group. Conversely, tubular/intertubular ratio was increased in TE animals (P < 0.01). Quantitative real-time PCR analysis of mRNA expression of testicular tissue revealed no significant differences among groups for StAR, CYP17A1 and androgen receptors. TE animals showed decreased CYP19A1 mRNA expression (P < 0.05). In the first 4 postnatal weeks, fecal testosterone (T) values were high, basal and intermediate in TE, MA and PL (P < 0.05), respectively. These differences progressively diminished and the three groups presented basal T concentrations from the 7th week on (P > 0.05). It was concluded that the postnatal progestagen initially suppressed the gonadal axis and caused an impairment of spermatogenesis and testicular descent at puberty. Androgen treatment caused downregulation of the final steroidogenic cascade.

Selective oestrogen receptor modulators decrease the inflammatory response of glial cells.

Neuroinflammation comprises a feature of many neurological disorders that is accompanied by the activation of glial cells and the release of pro-inflammatory cytokines and chemokines. Such activation is a normal response oriented to protect neural tissue and it is mainly regulated by microglia and astroglia. However, excessive and chronic activation of glia may lead to neurotoxicity and may be harmful for neural tissue. The ovarian hormone oestradiol exerts protective actions in the central nervous system that, at least in part, are mediated by a reduction of reactive gliosis. Several selective oestrogen receptor modulators may also exert neuroprotective effects by controlling glial inflammatory responses. Thus, tamoxifen and raloxifene decrease the inflammatory response caused by lipopolysaccharide, a bacterial endotoxin, in mouse and rat microglia cells in vitro. Tamoxifen and raloxifene are also able to reduce microglia activation in the brain of male and female rats in vivo after the peripheral administration of lipopolysaccharide. In addition, tamoxifen decreases the microglia inflammatory response induced by irradiation. Furthermore, treatment with tamoxifen and raloxifene resulted in a significant reduction of the number of reactive astrocytes in the hippocampus of young, middle-aged and older female rats after a stab wound injury. Tamoxifen, raloxifene and the new selective oestrogen receptor modulators ospemifene and bazedoxifene decrease the expression and release of interleukine-6 and interferon-γ inducible protein-10 in cultured astrocytes exposed to lipopolysaccharide. Ospemifene and bazedoxifene exert anti-inflammatory effects in astrocytes by a mechanism involving classical oestrogen receptors and the inhibition of nuclear factor-kappa B p65 transactivation. These data suggest that oestrogenic compounds are candidates to counteract brain inflammation under neurodegenerative conditions by targeting the production and release of pro-inflammatory molecules by glial cells.

Increased aromatase expression in the hippocampus of spontaneously hypertensive rats: effects of estradiol administration.

There is high incidence of hippocampal abnormalities in spontaneously hypertensive rats (SHR), including decreased neurogenesis in the dentate gyrus, astrogliosis, low expression of brain derived neurotrophic factor and decreased neuronal density in the hilar region, respect of normotensive Wistar Kyoto rats (WKY). Estradiol treatment given for 2 weeks normalized the faulty hippocampal parameters of SHR, without having effects on WKY rats. The present work studied the potential role of local estrogen biosynthesis in the hippocampus of SHR and WKY, by measuring the expression of aromatase, the key enzyme responsible for estrogen biosynthesis and involved in neuroprotection. We used 4 month old male SHR and WKY, half of which received a single sc pellet of 12 mg estradiol benzoate and the remaining half a cholesterol implant. Hippocampi were dissected and processed for aromatase mRNA expression using real time PCR. A second batch of animals was processed for aromatase and glial fibrillary acidic protein (GFAP) immunocytochemistry. Basal level of aromatase mRNA was higher in SHR respect of WKY. Following estradiol treatment, aromatase mRNA was further increased in the SHR group only. In the hilus of the dentate gyrus of cholesterol-implanted SHR, we found aromatase immunoreactive cell processes and fibers more strongly stained respect of WKY rats. Estradiol treatment of SHR further increased the length of immunoreactive processes and fibers in the hilar region and also increased aromatase immunoreactivity in the CA1 but not the CA3 pyramidal cell region. WKY rats were spared from the estradiol effect. Double-labelling experiments showed that aromatase+ processes and fibers of the hilus of SHR-treated rats did no colocalize with GFAP+ astrocyte cell bodies or processes. In conclusion, basal and estradiol-stimulated aromatase expression was enhanced in hypertensive rat hippocampus. A combination of exogenous estrogens and those locally synthesized may better alleviate hypertensive encephalopathy.

Glial cell line-derived neurotrophic factor gene therapy ameliorates chronic hyperprolactinemia in senile rats.

Progressive dysfunction of hypothalamic tuberoinfundibular dopaminergic (TIDA) neurons during normal aging is associated in the female rat with chronic hyperprolactinemia. We assessed the effectiveness of glial cell line-derived neurotrophic factor (GDNF) gene therapy to restore TIDA neuron function in senile female rats and reverse their chronic hyperprolactinemia. Young (2.5 months) and senile (29 months) rats received a bilateral intrahypothalamic injection (10(10) pfu) of either an adenoviral vector expressing the gene for beta-galactosidase; (Y-betagal and S-betagal, respectively) or a vector expressing rat GDNF (Y-GDNF and S-GDNF, respectively). Transgenic GDNF levels in supernatants of GDNF adenovector-transduced N2a neuronal cell cultures were 25+/-4 ng/ml, as determined by bioassay. In the rats, serum prolactin (PRL) was measured at regular intervals. On day 17 animals were sacrificed and neuronal nuclear antigen (NeuN) and tyrosine hydroxylase (TH) immunoreactive cells counted in the arcuate-periventricular hypothalamic region. The S-GDNF but not the S-betagal rats, showed a significant reduction in body weight. The chronic hyperprolactinemia of the senile females was significantly ameliorated in the S-GDNF rats (P<0.05) but not in the S-betagal rats. Neither age nor GDNF induced significant changes in the number of NeuN and TH neurons. We conclude that transgenic GDNF ameliorates chronic hyperprolactinemia in aging female rats, probably by restoring TIDA neuron function.

Gene therapy in the neuroendocrine system.

The implementation of experimental gene therapy in animal models of neuroendocrine diseases is an area of growing interest. In the hypothalamus, restorative gene therapy has been successfully implemented in Brattleboro rats, an arginine vasopressin (AVP) mutant which suffers from diabetes insipidus, and in Koletsky (fa(k)/fa(k)) and in Zucker (fa/fa) rats which have leptin receptor mutations that render them obese, hyperphagic and hyperinsulinemic. In the above models, viral vectors expressing AVP, leptin receptor b and proopiomelanocortin, respectively, were stereotaxically injected in the relevant hypothalamic regions. In rats, aging brings about a progressive degeneration and loss of hypothalamic tuberoinfundibular dopaminergic (TIDA) neurons, which are involved in the tonic inhibitory control of prolactin secretion and lactotropic cell proliferation. Stereotaxic injection of an adenoviral vector expressing insulin-like growth factor I corrected their chronic hyperprolactinemia and restored TIDA neuron numbers. Spontaneous intermediate lobe pituitary tumors in a retinoblastoma (Rb) gene mutant mouse were corrected by injection of an adenoviral vector expressing the human Rb cDNA and experimental prolactinomas in rats were partially reduced by intrapituitary injection of an adenoviral vector expressing the HSV1-thymidine kinase suicide gene. These results suggest that further implementation of gene therapy strategies in neuroendocrine models may be highly rewarding.

Effect of simvastatin on the uptake and metabolic conversion of palmitic, dihomo-gamma-linoleic and alpha-linolenic acids in A549 cells.

It is well known that simvastatin affects cholesterol synthesis. Furthermore it inhibits growth and proliferation and perturbs fatty acid metabolism in some cell lines. We have studied the effects of simvastatin on the uptake and metabolism of exogenous fatty acid in the human lung adenocarcinoma A549 cells. Simvastatin inhibited the proliferation of A549, and caused an increment in phospholipid/cholesterol ratio due to an increment in phospholipid content without affecting cholesterol content. All the fatty acids were uptaken and metabolized in both control and treated cells. The conversion of palmitic, linoleic and dihomo-gamma-linoleic acids to their metabolites and products/precursor ratios for the desaturation and elongation reactions showed that simvastatin enhanced the Delta5 desaturation step and altered some elongating steps. The machinery for unsaturated fatty acid synthesis in A549 is quite sensitive to simvastatin and its effects could have important implication taking into account that highly unsaturated fatty acids are involved in the regulation of diverse cellular functions by themselves or through their metabolites.

Hearing-aids: can they be safely prescribed without medical supervision? An analysis of patients referred for hearing-aids.

A prospective study of 169 patients with hearing loss as their main symptom, referred to the ENT Clinic by General Practitioners, is reported. The study aimed to assess the safety of prescribing hearing aids by Physiological Measurement Technicians from the Audiology Department without medical supervision. The General Practitioners' referral letter and patients' histories were analysed to see if all cases of middle ear disease would be picked up from this information alone. In this study, 31 patients had otoscopic evidence of chronic otitis media, active or inactive, only 14 (45.2%) of whom were identifiable from the referral letters. Of the 8 cases of active inflammatory ear disease, 3 were not mentioned in the referral letter. No asymptomatic cholesteatoma was found in the study population. At present all patients are reviewed by ENT medical staff prior to prescription of a hearing-aid; we feel this should continue.

An evaluation of common cerumenolytic agents: an in-vitro study.

Four non-prescription cerumenolytic agents were acquired over the counter of a high-street chemist and evaluated along with Sodium Bicarbonate ear drops BP, olive oil, distilled water, and acetone in an in-vitro study. Sodium Bicarbonate ear-drops BP are used by the nurses in the department and are recommended in the British National Formulary as the most effective solution to soften cerumen prior to syringing. Acetone was included as an effective organic solvent. The test was performed in a water bath, controlled to match the temperature of the external auditory meatus. Disintegration of the cerumen was noted over a two-hour period. Substantial disintegration occurred with three products: Waxsol, Stores Own Brand, and distilled water.

Chlamydia: its influence in chronic secretory otitis media.

Since Chlamydia trachomatis was isolated from middle ear effusions of neonates with natally acquired chlamydial infection (Tipple et al., 1979), there have been several studies to detect chlamydia in older children with chronic secretory otitis media, mainly by tissue culture. In this study, the aspirates of 106 middle ear effusions of 60 children with chronic secretory otitis media were investigated for the presence of C. trachomatis, other bacteria and viruses. An amplified enzyme-linked immunoassay was used to detect the presence of chlamydia. The bacteriological and virological results mirrored previous studies in the United Kingdom and no chlamydia were found. Chlamydia do not appear to be related to the aetiology of this disease in the population examined.

Fat graft myringoplasty--a prospective trial.

A prospective trial to determine the success rate of the fat graft myringoplasty technique is reported. A success rate of 76% overall was attained at review 1 year postoperatively with increased success for smaller perforations of the tympanic membrane.