Biomedical subjects

Hernán E Lara

Publications and source records attributed to Hernán E Lara.

5 recordsLinked to original sources

PubMed2006

Effects of nerve growth factor (NGF) on blood vessels area and expression of the angiogenic factors VEGF and TGFbeta1 in the rat ovary.

BACKGROUND: Angiogenesis is a crucial process in follicular development and luteogenesis. The nerve growth factor (NGF) promotes angiogenesis in various tissues. An impaired production of this neurotrophin has been associated with delayed wound healing. A variety of ovarian functions are regulated by NGF, but its effects on ovarian angiogenesis remain unknown. The aim of this study was to elucidate if NGF modulates 1) the amount of follicular blood vessels and 2) ovarian expression of two angiogenic factors: vascular endothelial growth factor (VEGF) and transforming growth factor beta 1 (TGFbeta1), in the rat ovary. RESULTS: In cultured neonatal rat ovaries, NGF increased VEGF mRNA and protein levels, whereas TGFbeta1 expression did not change. Sectioning of the superior ovarian nerve, which increases ovarian NGF protein content, augmented VEGF immunoreactivity and the area of capillary vessels in ovaries of prepubertal rats compared to control ovaries. CONCLUSION: Results indicate that NGF may be important in the maintenance of the follicular and luteal vasculature in adult rodents, either indirectly, by increasing the expression of VEGF in the ovary, or directly via promoting the proliferation of vascular cells. This data suggests that a disruption on NGF regulation could be a component in ovarian disorders related with impaired angiogenesis.

Animals↗

PubMed2006

Nerve growth factor and its high-affinity receptor trkA participate in the control of vascular endothelial growth factor expression in epithelial ovarian cancer.

OBJECTIVES: To compare the expression of nerve growth factor (NGF) and its high-affinity receptor trkA in normal ovaries and in epithelial ovarian carcinomas. Given NGF acts as an angiogenic factor through a vascular endothelial growth factor (VEGF)-mediated mechanism in several types of tissues, we examined whether NGF regulates the expression of VEGF isoforms in epithelial ovarian cancer (EOC). METHODS: The expression and localization of NGF and tyrosine kinase receptor A (trkA) in normal ovarian samples and in ovarian cancer samples were analyzed by RT-PCR and immunohistochemistry. NGF regulates the expression of three VEGF isoforms (VEGF(121), VEGF(165) and VEGF(189)); these were examined using RT-PCR in explants of EOC and ELISA in culture media. RESULTS: TrkA mRNA levels were over-expressed in ovarian cancer compared to normal ovarian samples, whereas NGF mRNA levels remained unchanged. NGF and trkA proteins were absent or found in very low levels in normal ovarian surface epithelium (OSE), whereas they were highly expressed in epithelial cells of EOC. Additionally, NGF stimulated the expression of VEGF isoforms in cancer explants. The effect was dose-dependent and inhibited by a NGF antibody and by K(252a), a trk receptor inhibitor. CONCLUSION: The abundance of NGF and trkA receptors in epithelial cells of EOC, together with the ability of NGF to increase VEGF expression strongly suggests an autocrine role of NGF in EOC. These findings suggest that blocking neurotrophin action could be a therapeutic target in treating ovarian cancer.

Adult↗

PubMed2006

Adrenalectomy promotes a permanent decrease of plasma corticoid levels and a transient increase of apoptosis and the expression of Transforming Growth Factor beta1 (TGF-beta1) in hippocampus: effect of a TGF-beta1 oligo-antisense.

BACKGROUND: Corticosterone reduction produced by adrenalectomy (ADX) induces apoptosis in dentate gyrus (DG) of the hippocampus, an effect related to an increase in the expression of the pro-apoptotic gene bax. However it has been reported that there is also an increase of the anti-apoptotic gene bcl-2, suggesting the promotion of a neuroprotective phenomenon, perhaps related to the expression of transforming growth factor beta1 (TGF-beta1). Thus, we have investigated whether TGF-beta1 levels are induced by ADX, and whether apoptosis is increased by blocking the expression of TGF-beta1 with an antisense oligonucleotide (ASO) administered intracerebrally in corticosterone depleted rats. RESULTS: It was observed an increase of apoptosis in DG, 2 and 5 days after ADX, in agreement with a reduction of corticosterone levels. However, the effect of ADX on the number of apoptotic positive cells in DG was decreased 5 days after the lesion. In CA1-CA3 regions, the effect was only observed 2 days after ADX. TGF-beta1 mRNA levels were increased 2 days after ADX. The sustained intracerebro-ventricular administration of a TGF-beta1 ASO via an osmotic mini pump increased apoptosis levels in CA and DG regions 5 days after ADX as well as sham-operated control animals. No significant effect was observed following a scrambled-oligodeoxynucleotide treatment. CONCLUSION: The changes in both the pattern and the magnitude of apoptotic-cell morphology observed 2 and 5 days after ADX suggest that, as a consequence of the reduction of corticosteroids, some trophic mechanisms restricting cell death to a particular time window are elicited. Sustained intracerebral administration of TGF-beta1 ASO increased the apoptosis promoted by ADX, suggesting that TGF-beta1 plays an anti-apoptotic role in vivo in hippocampus.

Adrenalectomy↗

PubMed2005

Role of stress and sympathetic innervation in the development of polycystic ovary syndrome.

This article presents a review of the role of the sympathetic activity in ovarian pathologies affecting reproductive function. We provide a succinct outline of the findings of our group in this area. The participation of stress as an etiological factor for ovarian pathologies throughout animal models and data in patients with polycystic ovary syndrome give strong support for participation of sympathetic nerves in the ovary function both in normal and pathological status.

Animals↗

PubMed2003

Prepubertal administration of estradiol valerate disrupts cyclicity and leads to cystic ovarian morphology during adult life in the rat: role of sympathetic innervation.

Administration of estradiol valerate (EV) to adult rats leads to anovulation and cystic ovarian morphology. Sympathetic ovarian nerve denervation (SONX) overcomes this disruption. In this study, we determined whether EV administration to juvenile rats prevents achievement of reproductive competence, disrupts cyclicity, and whether this programming is facilitated via activation of the sympathetic nerve input to the ovary. Prepubertal rats were administered 2 mg EV in corn oil or corn oil alone. One half of the animals from each group underwent SONX on d 71 of life. Rats were euthanized on d 91 for determination of serum gonadotropins, progesterone, Delta4 androstenedione, and estradiol concentrations, ovarian norepinephrine (NE), and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activities and ovarian dynamics. Results revealed that EV administration during juvenile period advanced pubertal onset, suppressed circulating LH, FSH, and Delta4 androstenedione, increased ovarian NE, estradiol, and 3beta-HSD activities, disrupted ovarian dynamics evidenced as absent corpus luteum and presence of ovarian cysts and culminated in anovulation. SONX restored cyclicity in these animals, normalized LH, estradiol, ovarian 3beta-HSD activities, and ovarian dynamics as evidenced by the disappearance of ovarian cysts and appearance of corpus luteum and restored corpus luteum function. These findings provide evidence that EV exposure during juvenile life leads to long-lasting deleterious reproductive consequences via activation of the sympathetic ovarian nerve.

Aging↗