Gender differences in the antioxidant response of oral administration of hydroxytyrosol and oleuropein against N-ethyl-N-nitrosourea (ENU)-induced glioma.

Brain tumorigenesis has been associated not only with oxidative stress, but also with a reduced response of non-enzyme and enzyme antioxidant defense systems. In fact, the imbalance between free-radical production and the efficiency of the antioxidant defense systems triggers the process because the central nervous system (CNS) is very sensitive to free-radical damage. Phenolic compounds, mainly oleuropein and its major metabolite hydroxytyrosol, derived from olives and virgin olive oil, have been shown to exert important anticancer activities both in vitro and in vivo due to their antioxidant properties. The present study analyzes the effects of the oral administration of oleuropein, hydroxytyrosol and the mixture of both phenolic compounds in rats with transplacental N-ethyl-N-nitrosourea (ENU)-induced brain tumors to analyze their potential effect against brain tumorigenesis through the modification of redox system components. Oxidative stress parameters, non-enzyme and enzyme antioxidant defense systems and blood chemistry were assayed in the different experimental groups. The treatment with oleuropein, hydroxytyrosol and/or the mixture of both phenolic compounds promotes a limited beneficial effect as anticancer compounds in our ENU-induced animal model of brain tumor. These effects occur via redox control mechanisms involving endogenous enzymatic and non-enzymatic antioxidant defense systems, and are highly dependent on the gender of the animals.

Local thyroid renin-angiotensin system in experimental breast cancer.

UNLABELLED: An association between breast cancer and thyroid dysfunction exists although the underlying mechanisms remain to be elucidated. Numerous studies have characterized the role of thyroid hormones in controlling the synthesis and secretion of renin-angiotensin system (RAS) components, but little information is available on the putative role of the local RAS on thyroid function. AIMS: Here we analyze several soluble and membrane-bound RAS-regulating aminopeptidase activities in thyroid gland from rats with mammary tumors and the relationship with the circulating levels of thyroid stimulating hormone (TSH) and free thyroxin (fT4). MAIN METHODS: We analyze soluble and membrane-bound RAS-regulating aminopeptidase activities fluorometrically using their corresponding aminoacyl-ß-naphthylamide as the substrate. KEY FINDINGS: We have found in rats with mammary tumors a concomitant change of thyroid RAS-regulating enzymes and thyroid hormone production. SIGNIFICANCE: We suggest that existence of alterations in the regulatory mechanisms mediated by the angiotensins of the local tissue RAS as a consequence of the carcinogenic process which could act alone or in combination with alterations at a higher level of regulation such as the hypothalamus-pituitary axis.

Intraoperative sentinel node biopsy by one-step nucleic acid amplification (OSNA) avoids axillary lymphadenectomy in women with breast cancer treated with neoadjuvant chemotherapy.

BACKGROUND: There is no evidence that supports the recommendation of sentinel lymph node biopsy (SLNB) in patients with breast cancer who have treated with neoadjuvant chemotherapy (NAC) to downsize tumors in order to allow breast conservation surgery, because NAC induces anatomical alterations of the lymphatic drainage. We evaluated the effectiveness of SLNB using intraoperative one-step nucleic acid amplification (OSNA) method to detect microscopic metastases or isolated tumor cells after NAC in patients with clinically negative axillary nodes at initial presentation. PATIENTS AND METHODS: We evaluated in patients with breast cancer and clinically negative axilla at presentation, the effectiveness of SLNB by OSNA after NAC (71 patients) or prior to NAC (40 patients). RESULTS: The rate of SLN identification was 100% in both groups. 17 women with SLNB prior to systemic treatment showed positive nodes (14 macrometastases and 3 micrometastases), and positive SLNB were detected in 15 women with SLNB after NAC, which were 14 macrometastases and 1 micrometastase. The negative predictive value of ultrasonography was 57.5% in patients with SLNB prior to neoadjuvant therapy and 78.9% in patients with chemotherapy followed by SLNB. CONCLUSIONS: Intraoperative SLNB using OSNA in women with clinically negative axillary lymph nodes at initial presentation who received NAC could predict axillary status with high accuracy. Also it allows us to take decisions about the indication or not to perform an axillary dissection at the moment, thus avoiding delay in the administration of chemotherapy and benefiting the patients from a single surgical procedure.

Effect of different degrees of impaired glucose metabolism on the expression of inflammatory markers in monocytes of patients with atherosclerosis.

Inflammatory markers are elevated in type 2 diabetic patients (DP) and may predict the development of type 2 diabetes. Our aims were to analyze differences in the expression of inflammatory and immunological molecules between DP and healthy subjects and to investigate whether glycemic control might prevent the overexpression of inflammatory markers in DP. Twenty-two DP with advanced atherosclerosis and eight healthy blood donors were included. DP were classified as well (HbA1c ≤ 6.5) or poorly controlled (HbA1c > 6.5). In "in vitro" studies, monocytes were exposed to low (5.5 mM) or high glucose (26 mM) concentrations in the absence or presence of insulin. Expression profiling of 14 inflammatory genes was analyzed using TLDA analysis. "In vivo" results show that monocytes from DP had increased levels of monocyte chemoattractant protein (MCP-1) and interleukin 6 (IL6) and lower levels of Toll-like receptor 2 (TLR2) mRNA than healthy subjects. Well-controlled DP had lower levels of IL-6 than poorly controlled DP, suggesting that glycemic control may prevent IL6 mRNA alterations associated with diabetes. "In vitro" results demonstrate that glucose directly and significantly induced MCP-1 and IL6 and reduced TLR2 mRNA expression. Insulin at high dose (100 IU/ml) dramatically enhanced the upregulatory effects of glucose on MCP-1 and IL-6 and reduced per se TLR2 mRNA expression. MCP-1, IL-6 and TLR2 are key inflammatory players altered in monocytes from type 2 DP. Both hyperinsulinemia and hyperglycemia contribute to alter the expression of these genes. The glycemic control only significantly prevented IL6 overexpression in this group of patients.

Plasma oxidative stress parameters in men and women with early stage Alzheimer type dementia.

It is well known that oxidative stress is one of the earliest events in Alzheimer's disease pathogenesis, indicating that may play a key role in this disease. In our study, we measured the levels of oxidative stress indicators (TBARS and protein carbonyls content) and the non-enzymatic (glutathione (GSH) and oxidized glutathione (GSSG)) and enzymatic (glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD)) defense systems in the plasma of 46 patients diagnosed of ATD and 46 age-matched controls. We found decreased levels in total GSH in ATD patients, although healthy control women showed lower levels of total GSH than healthy control men. On the contrary, we found increased levels of TBARS and carbonyl groups content in ATD patients in both genders. The activity of the plasma antioxidant enzymes showed no changes for SOD activity in ATD patients, independently of the gender, although western blot analysis showed an increase in SOD-1 protein. CAT activity was also decreased in ATD patients, although this decrease is mainly due to the decrease found in men but not in women. However, western blot analysis did not show differences in CAT protein between controls and ATD patients. Finally, a decrease of GPx activity was found in ATD patients in both genders. However, as with CAT protein, western blot analysis did not show differences in GPx protein between controls and ATD patients. Our results suggest that there is a defect in the antioxidant defense system that is incapable of responding to increased free radical production, which may lead to oxidative damage and the development of the pathological alterations that characterize the neurodegenerative disorder of patients with ATD. Thus, oxidative damage could be one important aspect for the onset of ATD and oxidative stress markers could be useful to diagnose the illness in their earliest stages through both non-invasive, reliable and cost-affordable methods.

Renin-angiotensin system-regulating aminopeptidase activities are modified in the pineal gland of rats with breast cancer induced by N-methyl-nitrosourea.

OBJECTIVE: Pineal function has been considered particularly as a neuroendocrine modulator in hormone responsive tumors, like the hormone-dependent mammary tumors. The complexity of the gland function, moreover, is denoted by the presence of a local renin-angiotensin-system (RAS) that regulates melatonin biosynthesis. Classically, angiotensin II (Ang II) has been considered as the effector peptide of the RAS, but Ang II is not the only active peptide. Several of its degradation products, including angiotensin III (Ang III) and angiotensin IV (Ang IV) also possess biological functions. These peptides are formed via the activity of several aminopeptidases. Our aim is to know their role in the regulation of pineal RAS and breast cancer. DESIGN: Aminopeptidase N (APN), aminopeptidase B (APB) and aminopeptidase A (aspartyl- and glutamyl-aminopeptidase, APA) activities are measured in the pineal gland of rats with breast cancer induced by N-methyl nitrosourea (NMU). METHODS: Aminopeptidase activities were measured fluorimetrically using their corresponding aminoacyl-beta-naphthylamides as substrates. RESULTS: Specific APN and APB activities in pineal gland of controls and NMU-treated rats were not modified. Aspartyl aminopeptidase activity significantly decreased in NMU-treated rats when compared with control group. On the contrary, glutamyl aminopeptidase activity did not show significant differences between groups. CONCLUSIONS: We propose that the local RAS in pineal gland is modified in rats with breast cancer induced by NMU through the inhibition of AspAP activity, which may lead to increased levels of Ang II. Ang II could be responsible of the overproduction of melatonin, supporting a mechanism to restrain the promotion and/or progression of breast cancer.

Pyrrolidon carboxypeptidase activities in the hypothalamus-pituitary-thyroid and hypothalamus-pituitary-ovary axes of rats with mammary gland cancer induced by N-methyl nitrosourea.

Pyrrolidon carboxypeptidase is an omega-peptidase that hydrolyses N-terminal pyroglutamyl residues from biologically active peptides such as gonadotropin-releasing and thyrotrophin-releasing hormones. We previously described a decrease in both rat and human pyrrolidon carboxypeptidase activity with breast cancer, suggesting that gonadotropin-releasing hormone may be an important local intracrine, autocrine and/or paracrine hormonal factor in the pathogenesis of breast cancer while playing a role in the tumoral process. However, the other susceptible substrate of pyrrolidon carboxypeptidase, thyrotrophin-releasing hormone, may also be modified with breast cancer, supporting an association between breast cancer and thyroid disorders. The present work analyses soluble and membrane-bound pyrrolidon carboxypeptidase activities in the hypothalamus-pituitary-thyroid and hypothalamus-pituitary-ovary axes in N-methyl nitrosourea-induced breast cancer in rats. Our aim was to determine the possible relationship between gonadotropin-releasing hormone and thyrotrophin-releasing hormone regulation through pyrrolidon carboxypeptidase activity. We propose that pyrrolidon carboxypeptidase activity dysregulation at various local and systemic levels may participate in the initiation, promotion and progression of breast cancer induced in rat by N-methyl nitrosourea through the increase in gonadotropin-releasing hormone. Since pyrrolidon carboxypeptidase activity also acts on thyrotrophin-releasing hormone, the dysregulation of this enzyme's activity could indirectly affect hypothalamus-pituitary-thyroid axis function, and thus potentially represent a link between the diseases of thyroid and breast cancer.

Influence of hormonal status on enkephalin-degrading aminopeptidase activity in the HPA axis of female mice.

Opioids are involved in the regulation of hypothalamus-pituitary-adrenal (HPA) axis activity under physiological conditions. In the present work, we analyzed the influence of ovariectomy and estradiol (E), progesterone (P) or estradiol plus progesterone (E+P) replacement on soluble (S) and membrane-bound (MB) enkephalin-degrading aminopeptidase activity (EDA) in the HPA axis. Female mice (Balb/C) were distributed in 15 groups of 10 animals each: sham-operated controls (C), ovariectomized controls (OV-C), and ovariectomized mice treated with increasing doses of E (10, 20 or 40 mg/kg), P (100, 200 or 400 mg/kg) or E+P (10+100, 20+200 or 40+400 mg/kg). In hypothalamus, ovariectomy increased both S and MB EDA activities, whereas E replacement returned them to control levels, although MB EDA activity increased again after the replacement with 40 mg/kg E. P replacement increased S EDA activity, but returned MB EDA activity to control levels. The replacement of E+P returned both S and MB EDA activities to control levels, although MB EDA activity was lower than control values after the replacement with 10+100 mg/kg E+P. In pituitary, neither ovariectomy nor the replacement of E or E+P changed S EDA, although the highest concentrations of P increased S EDA activity. However, ovariectomy increased MB EDA and E replacement returned the activity to control or below control levels, depending on the concentration used. However, P administration returned the activity to control or below control levels depending on the concentration used, although 200 mg/kg P had no effects on MB EDA. E+P replacement returned pituitary MB EDA activity to control levels. In adrenal glands, ovariectomy did change either S or MB EDA. However, E, P or E+P replacement decreased S EDA activity in different degrees, depending of the dose administrated. No changes were detected in MB EDA after hormone replacement. These results indicate that female steroid hormones influence EDA activity at different levels of HPA axis.

Chronic ethanol intake modifies renin-angiotensin system-regulating aminopeptidase activities in mouse cerebellum.

In developing cerebellum, where critical periods of vulnerability have been established for several basic substances, it has been extensively studied the wide array of abnormalities induced by exposure to ethanol (EtOH). However, little is known about the effects of EtOH consumption on cerebellar functions in adult individuals. Several studies show participation in cognitive activities to be concentrated in the lateral cerebellum (hemispheres), whereas basic motor functions such as balance and coordination are represented in the medial parts of the cerebellum (vermis and paravermis). In addition to the circulating renin angiotensin system (RAS), a local system has been postulated in brain. The effector peptides of the RAS are formed via the activity of several aminopeptidases (AP). The present work analyses the effect of chronic EtOH intake on the RAS-regulating AP activities in the soluble and membrane-bound fractions of two cerebellar locations: the hemispheres and the vermis. We hypothesize that cerebellar RAS is involved in basic motor functions rather than in cognitive activities.

Serum oxytocinase activity is related to tumor growth parameters in N-methyl nitrosourea induced rat breast cancer.

Oxytocinase has been reported to hydrolyse the peptide hormone oxytocin (OT). We have previously described changes in oxytocinase activity in human breast cancer, where a highly significant increase occurred in tumoral tissue. In the present work, we analysed oxytocinase activity in serum of rats with breast cancer induced by N-methyl-nitrosourea (NMU). We also correlated these data with the number and size of tumors and the body weight of the animals to evaluate the putative value of this activity as a biological marker of the disease. Our results confirm the involvement of OT in carcinogenesis and suggest a mayor role for oxytocinase activity in the development of breast cancer.

Effects of orchidectomy and testosterone replacement on mouse pyrrolidone carboxypeptidase activity in the HPA axis.

Pyrrolidone carboxypeptidase, also known as pyroglutamyl aminopeptidase, removes pyroglutamyl terminal residues from biologically active peptides such as thyrotropin-releasing hormone. The aim of the present work was to study the influence of orchidectomy and testosterone replacement on soluble (pyrrolidone carboxypeptidase type I) and membrane-bound (pyrrolidone carboxypeptidase type II) activities in the hypothalamus-pituitary-adrenal axis. Forty male mice (Balb/C) were distributed into five groups: sham-operated controls, orchidectomized, and orchidectomized treated with increasing doses of testosterone in each group (3, 6 and 12 mg/kg). In the hypothalamus, orchidectomy increased pyrrolidone carboxypeptidase type I, whereas the highest dose of testosterone returned this activity to control levels. In the pituitary, neither pyrrolidone carboxypeptidase type I nor type II activities changed after orchidectomy, although both activities increased after administration of testosterone in both cases. On the other hand, orchidectomy increased pyrrolidone carboxypeptidase type I and type II activities in adrenal glands, while testosterone replacement returned it to control levels. These results suggest that testosterone differentially modulates pyrrolidone carboxypeptidase type I and type II activities, and therefore also their endogenous substrate regulation. Thus, the influence of sex hormones in the physiology of the HPA axis through the modulation of the Pyrrolidone carboxypeptidase type I and type II activities is of great importance on stress and neuropathology associated with HPA dysfunction

Actividad de las aminopeptidasas séricas en un modelo animal de cáncer de mama inducido por N-metil-nitrosourea / Activity of serum aminopeptidases in an animal model of N-metil-nitrosourea- induced breast cancer

Los factores hormonales responsables de la proliferación del tejido mamario normal durante la pubertad y los cambios cíclicos del ciclo menstrual podrían estar implicados en la promoción, la progresión y la aparición del cáncer de mama en humanos. Se ha sugerido que las enzimas proteolíticas del tipo de las aminopeptidasas, cuyo papel fisiológico consiste en la regulación de diversos péptidos biológicamente activos, podrían participar en el desarrollo del cáncer de mama. La finalidad del presente trabajo es analizar la actividad de un amplio espectro de aminopeptidasas en el suero de ratas con tumores de mama inducidos por N-metil-nitrosourea (NMU), para evaluar su posible valor como marcadores biológicos de esta enfermedad. La inducción de tumores con NMU mostró una incidencia tumoral del 60 por ciento, con un período de latencia medio de 113 días y un número medio de tumores por rata de 1,93. Las actividades específicas de aminopeptidasa N (APN) aminopeptidasa B (APB) aminopeptidasa A (APA) (aspartato aminopeptidasa [AspAP] y glutamato aminopeptidasa [AspAP], oxitocinasa y pirrolidón carboxipeptidasa se analizaron fluorimétricamente utilizando como sustrato las correspondientes aminoacil-naftilamidas. Los animales con cáncer de mama inducido por NMU mostraron incrementos significativos en los valores séricos de APB (32 por ciento; p < 0,01), GluAP (54 por ciento; p < 0,05) y oxitocinasa (45 por ciento; p < 0,05), mientras que los valores de pirrolidón carboxipeptidasa estaban disminuidos (28 por ciento; p < 0,05). Estos cambios pueden reflejar alteraciones en el metabolismo de las angiotensinas, la oxitocina y la hormona liberadora de gonadotropinas, que pueden ser, al menos en parte, responsables del inicio y/o desarrollo de la enfermedad (AU)

Effects of orchidectomy and testosterone replacement on mouse enkephalin-degrading aminopeptidase activity in the HPA axis.

Opiates are involved in the regulation of several functions in the hypothalamus-pituitary-adrenal (HPA) axis under physiological conditions. The aim of the present work is to study the influence of orchidectomy and testosterone (T) replacement on soluble (S) and membrane bound (MB) enkephalin-degrading aminopeptidase (EDA) activities in the HPA axis. Forty male mice (Balb/C) were distributed in five groups: sham-operated control (C), orchidectomized (OR-C), and orchidectomized treated with increasing doses of T (3, 6 or 12 mg/kg). In hypothalamus, orchidectomy did not modify either S or MB EDA, although T replacement increased S but not MB EDA. In pituitary, neither S nor MB EDA activities changed with orchidectomy, although both activities changed after T replacement. On the other hand, in adrenal glands, orchidectomy increased S and MB EDA activities, whereas T replacement returned both activities to control levels. These results suggest a direct effect of T in S and MB EDA activities and therefore, an influence on their endogenous substrates regulation.

Serum pyrrolidone carboxypeptidase activity in N-methyl-nitrosourea induced rat breast cancer.

Pyrrolidone carboxypeptidase (Pcp) (E.C. 3.4.19.3) is an omega peptidase widely distributed in animal fluids and tissues and hydrolyses N-terminal pyroglutamic residues from biologically active peptides such as gonadotropin releasing hormone (GnRH). Previous results obtained by us showed a decrease in human breast cancer Pcp activity, suggesting that this enzyme activity or its putative substrates may play a major role in breast cancer pathogenesis. The aim of the present work is to analyse serum Pcp activity in N-methyl-nitrosourea (NMU) induced rat mammary tumours using pyroglutamyl-beta-naphthylamide as substrate. Serum Pcp activity was significantly lower in NMU-treated rats than in controls. Moreover, multiple regression analysis showed a significant correlation between Pcp activity and the number and size of tumours and the body weight of the animals. Since NMU-induced carcinomas are mainly oestrogen-dependent, the decrease observed in Pcp activity may reflect an increase in circulating levels of GnRH that lead to an increase in gonadal steroid hormones production responsible, at least in part, for the initiation and promotion of the disease.

Effects of exogenous fatty acids and cholesterol on aminopeptidase activities in rat astroglia.

Several studies have addressed the interaction between fatty acids and lipids with central nervous system peptides. Because aminopeptidases (AP) are involved in the regulation of neuropeptides, this work studies several AP expressed in cultured astroglia, after exogenous addition of oleic and linoleic fatty acids and cholesterol to the culture medium. Alanyl-AP, arginyl-AP, cystyl-AP, leucyl-AP, tyrosyl-AP and pyroglutamyl-AP activities were analysed in whole cells using the corresponding aminoacyl-beta-naphthylamides as substrates. Oleic acid inhibits alanyl-AP, cystyl-AP and leucyl-AP activities, whereas linoleic acid inhibits alanyl-AP, arginyl-AP and tyrosyl-AP activities. Neither oleic acid nor linoleic acid modifies pyroglutamyl-AP activity. In contrast, cholesterol increases arginyl-AP, cystyl-AP, leucyl-AP, tyrosyl-AP and pyroglutamyl-AP activities, although it does not modify alanyl-AP activity. The changes reported here suggest that oleic and linoleic fatty acids and cholesterol can modulate peptide activities via their degradation route involving aminopeptidases; each of them being differentially regulated.

[Physiology of the neuropeptides]. / Fisiología de los neuropéptidos.

In the present review, the characteristics of mammalian neuropeptides have been studied. Neuropeptides are widely distributed not only in the nervous system but also in the periphery. They are synthesised by neurons as large precursor molecules (pre propeptides) which have to be cleaved and modified in order to form the mature neuropeptides. Neuropeptides may exert actions as neurotransmitters, neuromodulators and/or neurohormones. In the neurons, they coexist with classic transmitters and often with other peptides. After their releasing, they bind to especific receptors to exert their action in the target cell. Most of these receptors belongs to a family of G protein coupled receptors. Finally, peptidases are the enzymes involved in the degradation of neuropeptides. Conclusions. In the last years, the number of known neuropeptides and the understanding of their functions have been increased. With these data, present investigations are looking for the treatment of different pathologies associated with alterations in the physiology of neuropeptides.

Fisiología de los neuropéptidos / Physiology of neuropeptides

Objetivos. En la presente revisión se pretenden analizar las características generales de los neuropéptidos de los mamíferos.Desarrollo. Los neuropéptidos son sustancias distribuidas de forma ubicua tanto en el sistema nervioso como en la periferia. Se sintetizan en la neurona a partir de prepropéptidos de gran tamaño que se escinden y se modifican hasta formar el neuropéptido maduro. Los neuropéptidos pueden ejercer funciones como neurotransmisores, pero también se han descrito como neuromoduladores o neurohormonas. En la neurona se almacenan en vesículas donde coexisten con neurotransmisores clásicos y, a veces, con otros péptidos. Una vez liberados, se unirán a receptores específicos para ejercer su acción en la célula diana. La mayoría de estos receptores pertenecen a la familia de receptores acoplados a una proteína G. Finalmente, las peptidasas son las enzimas encargadas de su degradación. Conclusiones. En los últimos años, el número de neuropéptidos se ha incrementado considerablemente y además son cada vez mejor conocidas las funciones en las que se ven implicados. En base a estos datos, las investigaciones recientes se están dirigiendo hacia la búsqueda de tratamientos para patologías asociadas con alteraciones de los neuropéptidos (AU)

Effects of dietary cholesterol on pyroglutamyl aminopeptidase activity in mouse frontal cortex, pituitary, and adrenal glands.

Pyroglutamyl aminopeptidase (pGluAP) is an omega peptidase that hydrolyzes biologically active peptides, such as thyrotropin-releasing hormone (TRH), with neuronal and extraendocrine functions. We analyzed the effects of a cholesterol-enriched diet on soluble and membrane-bound pGluAP activity in frontal cortex, pituitary and adrenal glands of male and female mice using fluorimetric assays. Significant increases were observed in soluble pGluAP activity in the frontal cortex and adrenal glands in males and in the pituitary in females. Membrane-bound pGluAP activity was increased in the frontal cortex and pituitary of males and females after the mice were fed a cholesterol-enriched diet. These increases may produce changes in the metabolism of endogenous substrates, including TRH, which may be related to alterations in its neuromodulator functions and to the possible relationship between TRH and other neurotransmitter systems.

[Influence of estradiol on pyroglutamyl aminopeptidase activity in the frontal cortex of ovariectomized mice]. / Influencia del estradiol sobre la actividad piroglutamato aminopeptidasa en la corteza frontal de ratones ovaridectomizados.

INTRODUCTION: Pyroglutamyl aminopeptidase (pGluAP) is an omega peptidase widely distributed in fluid and tissues which hydrolyses biological active peptides including thyrotropin releasing hormone (TRH). OBJECTIVES. The aim of present work is to study the influence of estradiol on soluble and membrane bound pGluAP activity in the frontal cortex of female mice. MATERIAL AND METHODS: Soluble and membrane bound pGluAP activities in frontal cortex of ovariectomized mice and ovariectomized mice injected with different doses of estradiol were measured using espectrophotometric assays. RESULTS: Soluble pGluAP activity in frontal cortex did not change after ovariectomy or after the administration of the different doses of estradiol. However, membrane bound pGluAP activity showed a significant increase after ovariectomy. After the administration of the lower dose of estradiol, membrane bond pGluAP activity returned to the same levels detected before the ovariectomy. CONCLUSION: Estradiol modifies membrane bound pGluAP activity which is the principal enzyme involved in the hydrolysis of TRH. Therefore, misregulation of estradiol levels may produce modifications in the neuromodulatory functions of TRH.

Pituitary aminopeptidase activities involved in blood-pressure regulation are modified by dietary cholesterol: sex differences.

Given that the existence of a local renin-angiotensin system (RAS) in the pituitary and its participation in the regulation of blood pressure and other biological functions are widely accepted, the aim of this work is to analyze the influence of dietary cholesterol on the activity of the enzymes involved in the metabolism of the effector peptides of the renin-angiotensin system (angiotensin II and III) and vasopressin, in the pituitary of male and female mice fed on a cholesterol-enriched diet (1% cholesterol and 0.5% cholic acid). Soluble and membrane-bound pituitary aminopeptidase A (aspartyl- and glutamyl-aminopeptidase), aminopeptidase M (alanyl-aminopeptidase), aminopeptidase B (arginyl-aminopeptidase) and cystinyl-aminopeptidase activities were fluorimetrically measured. In female mice, cholesterol-enriched diet produced a significant increase in soluble aspartyl- and membrane-bound aspartyl- and glutamyl-aminopeptidase activities, and a significant decrease in membrane-bound alanyl-, arginyl- and cystinyl-aminopeptidase activities. In male mice, after feeding the diet, a significant increase in soluble glutamyl- and membrane-bound arginyl-aminopeptidase activities was observed. Our results indicate differential effects of dietary cholesterol on the metabolism of angiotensin II and III and vasopressin in the pituitary of male and female mice.