Evidence to suggest glutamic acid involvement in Bisphenol A effect at the hypothalamic level in prepubertal male rats.

Objectives: The aim of present paper was to study the probable role of glutamic acid (GLU) as a mediator of bisphenol A (BPA) effect at the hypothalamic level and its effects on the reproductive axis of prepubertal male rats.

Methods: Mated Wistar rats were treated with either 0.1% ethanol (control group, n=10) or BPA (BPA group, n=10) in their drinking water until their offspring were weaned at the age of 21 days.

Reproductive axis response to repeated lipopolysaccharide administration in peripubertal female rats.

Immune system disorders are often accompanied by alterations in the reproductive axis. Several reports have shown that administration of bacterial lipopolysaccharide (LPS) has central inflammatory effects and activates cytokine release in the hypothalamus where the luteinizing hormone releasing hormone (Gn-RH) neurons are located. The present study was designed to investigate the effect of repeated LPS administration on the neuroendocrine mechanisms of control of the reproductive axis in peripubertal female rats (30-day-old rats).

Impact of gestational and lactational phthalate exposure on hypothalamic content of amino acid neurotransmitters and FSH secretion in peripubertal male rats.

This study investigated the effect of the pre- and perinatal exposure to di-(2-ethylhexyl) phthalate (DEHP) on the neuroendocrine parameters that regulate reproduction in peripubertal male rats. DEHP at dose of 3 and 30mg/kg bw/day was administered orally to female rat since pregnancy onset until weaning. The male litters were sacrificed at 30 days of age to determine gonadotropin serum level and the hypothalamic contents of the amino acids aspartate and gamma-aminobutyric acid.

In vitro effect of octyl - methoxycinnamate (OMC) on the release of Gn-RH and amino acid neurotransmitters by hypothalamus of adult rats.

OMC (octyl-methoxycinnamate), an endocrine disruptor having estrogenic activity, is used in sunscreen creams as UV filter. We studied its "in vitro" effects on the hypothalamic release of Gn-RH as well as on the amino acid neurotransmitter system. OMC significantly decreased Gn-RH release in normal male and female rats as well as in castrated rats with substitutive therapy.

Impact of 4-methylbenzylidene-camphor (4-MBC) during embryonic and fetal development in the neuroendocrine regulation of testicular axis in prepubertal and peripubertal male rats.

4-Methylbenzylidene-camphor (4-MBC), an UV-B ray filter, belongs to the endocrine disrupters involved with alterations in the reproductive axis. Our target was to study the effect of 4-MBC on the neuroendocrine parameters that regulate reproduction in prepubertal and peripubertal male rats, which received this disrupter during embryonic and fetal development. 4-MBC was administered (sc) to female rats since pregnancy onset in doses of 20, 100 and 500 mg/kg/day.

Impact of the UV-B filter 4-(Methylbenzylidene)-camphor (4-MBC) during prenatal development in the neuroendocrine regulation of gonadal axis in male and female adult rats.

4-(Methylbenzylidene)-camphor (4-MBC), a UV-B ray filter, is an endocrine disruptors (ED). Our goal was to study the effect of 4-MBC on the neuroendocrine parameters that regulate reproduction in adult female and male rats that received this disrupter during prenatal development. The 4-MBC was administered (sc) to female rats (FO) since pregnancy onset, in doses of 100mg/kg every other day.

Low dose 4-MBC effect on neuroendocrine regulation of reproductive axis in adult male rats.

4-Methylbenzylidene camphor (4-MBC) is an ultraviolet absorbent. The objective of this paper was to evaluate the effect of 4-MBC low-dose exposure on the neuroendocrine reproductive regulation in male rats. Wistar male adult rats were injected sc.

Effect of bacterial lipopolysaccharide on the reproductive axis of prepubertal and peripubertal female rats. Ontogenic changes in the immune-neuroendocrine interactions.

The immune, endocrine and nervous systems are closely interrelated, which allows the organism to respond to different types of stress such as infection. Chronic infectious and inflammatory conditions are often accompanied by an impaired reproductive function. Leptin, a hormone produced by adipose tissue, exerts a regulatory function on the reproductive axis.

Octyl-methoxycinnamate (OMC), an ultraviolet (UV) filter, alters LHRH and amino acid neurotransmitters release from hypothalamus of immature rats.

OMC (octyl-methoxycinnamate), is an endocrine disruptor with estrogenic activity, which is used in sunscreen creams as a UV filter. We studied its " IN VITRO" effects on the hypothalamic release of LHRH as well as on the amino acid neurotransmitter system in immature rats of 15 (prepubertal) and 30 (peripubertal) days of age. OMC decreased the LH-RH release significantly in male and female rats of both age.

Nitric oxide synthase inhibition prevents leptin induced Gn-RH release in prepubertal and peripubertal female rats.

The aim of the present paper was to study the role of NO as a mediator of leptin action at the hypothalamic level during sexual maturation. First, we analyzed the effect of different leptin concentrations (10 (-13), 10 (-11) and 10 (-9) M) on Gn-RH release from anterior preoptic area and medio basal hypothalamus (APOA-MBH) of prepubertal (15 days old) and peripubertal (30 days old) female rats. Leptin 10 (-13) M was the most effective concentration in releasing Gn-RH in both groups of animals.

Leptin stimulates LH secretion in peripubertal male rats through NMDA receptors.

Leptin, a peptide hormone secreted by adipocytes that has been proposed as a metabolic signal in the reproductive system, appears to be linked to the different neuroendocrine processes involved in the onset of puberty. We studied the ontogenic effect of administration of leptin (30 mg/kg i.p.

Leptin stimulates the reproductive male axis in rats during sexual maturation by acting on hypothalamic excitatory amino acids.

The purpose of the present study was to determine the effect of treatment with leptin on gonadotrophin secretion and hypothalamic GnRH, excitatory and inhibitory amino acids release, in prepubertal (15 days old) and peripubertal (30 days old) male rats. Rats of both ages received a single (ip) injection of 30 microg/kg leptin 60 minutes previous to sacrifice. Serum LH was determined, and the hypothalamus dissected and incubated in Earle's medium.

Effect of leptin on LH levels and hypothalamic release of GnRH. Its relationship with the hypothalamic neurotransmitter amino acids system in adult male rats.

The objective of the present paper was to determine the effect of leptin on the reproductive axis in adult male rats, as well as the hypothalamic mechanisms involved in this effect. For this purpose, we studied the in vivo effect of leptin in adult male rats on serum LH levels, and the in vitro effect on hypothalamic GnRH and amino acid neurotrasmitter release. For in vivo experiments, animals were injected i.

Hypothalamic nitric oxide synthase activity during sexual maturation in female rats. Effects of estrogens.

Objectives: To determine the hypothalamic activity of nitric oxide synthase (NOS, the enzyme involved in the synthesis of nitric oxide NO) during sexual maturation in prepubertal (15 days old) and peripubertal female rats (30 days old) as well as the effect of estradiol administration on this neurotransmitter system.

Methods: Hypothalamic samples containing the anterior preoptic and medial basal areas (APOA-MBH) were homogenized with HEPES 20 mM, pH = 7.4 and NOS activity was determined in APO-MBH after 10 minutes of incubation by the conversion of 14C arginine to 14C citrulline.

Effect of leptin on hypothalamic release of GnRH and neurotransmitter amino acids during sexual maturation in female rats.

The purpose of the present study was to analyse the effect of leptin treatment on the hypothalamic release of GnRH, GABA, and the excitatory amino acids (EAA), aspartate (ASP) and glutamate (GLU) involved in NMDA neurotransmission in prepubertal (15 day old) and peripubertal (30 day old) female rats. The animals were treated with a single dose of leptin (30 microg/kg i.p.

Effects of gabaergic and serotoninergic systems on hypothalamic content of catecholamines during sexual development in female rats.

Objectives: The aim of the present investigation was to determine whether the catecholaminergic system is involved in gabaergic and serotoninergic effects on gonadotrophin secretion during sexual development. To this end, we studied the effect of GABAergic and serotoninergic systems on hypothalamic catecholamine content at different stages of sexual development.

Methods: The effect of GABA A and GABA B agonists and 5-hydroxy-L-tryptophan on hypothalamic noradrenaline and dopamine content were determined in prepubertal (16 days old) and peripubertal (30 days old) rats.

Changes in the effect of testosterone on hypothalamic nitric oxide synthetase during sexual maturation. Its relationship with GnRH release.

Objectives: To determine the effect of testosterone administration to prepubertal (15 days old) and peripubertal rats (30 days old) on hypothalamic nitric oxide synthetase (NOS), and GnRH release.

Methods: Hypothalamic samples containing the anterior preoptic and medial basal areas (APO-MBH) were incubated for 30 minutes in 500 l of Earle's medium with glucose (1 mg/ml) and bacitracin (20 mM). GnRH was determined by RIA in the medium and NOS activity was determined in APO-MBH after 10 min of incubation by the conversion of (14) C arginine to (14) C citrulline.

Ontogenic modifications in the effect of the GABAergic system on the hypothalamic excitatory amino acids: its relationship with GABAergic control of gonadotrophin secretion during sexual maturation in female rats.

Aminooxyacetic acid (AOAA), an inhibitor of gamma-aminobutyric transaminase, stimulates the in vitro GABA release by medial and anterior preoptic hypothalamic areas in prepubertal female rats (6, 15 and 30 days of age). This increase of GABA release at 15 days of age, was accompanied by a significant increase (P<0.01) in the hypothalamic release of glutamate (GLU) and aspartate (ASP), the excitatory amino acids involved in N-methyl-D-aspartate neurotransmission and a decrease in the release of these excitatory amino acids at 6 and 30 days of age (P<0.

Changes in the sensitivity of gonadotrophin axis to leptin during sexual maturation in female rats.

Objectives: The aim of the present paper was to determine the sensitivity of the GnRH-LH axis to leptin administration during sexual maturation in female rats.

Methods: For this purpose the hypothalamic concentration of GnRH, the pituitary content and the plasmatic levels of LH were determined in prepubertal (15 days of age) and peripubertal female rats (30 days of age), treated with leptin at a dose of 30 microg/kg. i.

Effects of aproteic diet on hypothalamic-pituitary- gonadal regulation in the male rat.

The effect of an aproteic diet (Ap) on the reproductive axis in young male rats was studied. Also the refeeding effect at different times after the aproteic diet was studied. The Ap diet was given during 21 days.

Effect of aproteic diet and fasting on insulin, pancreatic noradrenaline and luteinizing hormone. Changes after 24-hour refeeding.

OBJECTIVE AND DESIGN: the objective of this study performed in adult male rats was to determine the alteration in glycemic, insulin and gonadotrophin luteinizing hormone secretion, and noradrenaline pancreatic concentration caused by fasting (F) and aproteic diet (Ap) during 7 and 21 days respectively, as well as the recovery after 24-hour refeeding with control diet (Co). RESULTS: a significant decrease in glycemic levels was only achieved through fasting (F: 86 +/- 5.1 mg %), when compared with controls (Co: 107 +/- 5 mg %).

Interrelationships of GABAergic, serotoninergic and excitatory amino acid systems in its regulatory effect on prolactin secretion in prepubertal rats.

GABAergic, serotoninergic and excitatory amino acid systems (EAAs) regulate the prolactin (PROL) secretion in prepubertal female rats. The aim of the present paper was to determine the interrelationships of these systems on the control of this pituitary hormone. It was carried out through the following scheme: 1.

Effect of an aproteic diet on gonadotropin release response to GnRH and estrogen-progesterone in rats.

The fasting-induced gonadotropin function decrease is unspecific, because in this situation there is a lack of all nutrients. We report here the effect of specific protein lack in the diet during 21 days, on pituitary gonadotropin synthesis and response to exogenous GnRH in adult male rats. We also studied the effect of the aproteic diet (AP) on the positive feedback mechanism in adult female castrated rats.

Interactions between GABAergic and serotoninergic systems with excitatory amino acid neurotransmission in the hypothalamic control of gonadotropin secretion in prepubertal female rats.

The present studies were designed to study the interrelationships between GABAergic, serotoninergic and excitatory amino acids systems (EAAs) in the control of gonadotropin secretion in prepubertal female rats. For this purpose we determined the effects of N-methyl-D-aspartate (NMDA), an exogenous agonist of EAAs receptors, on LH and FSH secretion in 16-day-old female rats in which the GABA-A and GABA-B receptors were blocked by bicuculline and baclofen or serotonin (5-HT) depleted by p-choloroamphetamine (PCA). In addition the effects of the GABAergic and serotoninergic systems on LH and FSH secretion were evaluated in animals treated with dibenzocycloalkenimine (diocilpine MK-801), an antagonist of NMDA neurotransmission.

Effects of aging on N-methyl-D-aspartate (NMDA)-induced GnRH and LH release in female rats.

In order to evaluate if the changes of the hypothalamic-pituitary-ovary axis that induce a decrease in fertility and modifications in the sexual cycles during senescence involve modifications in the regulatory action of excitatory amino acid neurotransmission on GnRH neurons, we measured the in vitro effects of NMDA on GnRH release by the anterior preoptic and medial basal hypothalamic areas (APOA-MBH) of castrated aging (18 months old) and young (90 days of age) rats. In a second series of experiments the in vivo LH release response to intrahypothalamic (push-pull) administration of NMDA to aged and young castrated female rats was also determined. A similar rate of basal GnRH release was observed in old and young rats during the incubation time.