Amine neurotransmitter levels in male and female rats through developmental periods.

Monoamines (MA) such as dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5-HT) are now generally regarded as widely distributed and essential endogenous mediators contributing to the integration of reproductive physiology. MA measured in the hypothalamus tissue of male and female rats aged 1 to 90 days showed its own characteristic development pattern. Significant differences were observed at 5, 15, and 90 days of age in NE mean levels and at all ages except for 3 days of age in 5-HT mean levels. In contrast, no sex differences were seen in DA mean levels.

Environmental temperature and cryptorchidism: effects on pregnenolone-sulfatase of mice testicular tissue.

This study examined the capacity of abdominal organs, such as the scrotal testis, exposed to environmental temperature to hydrolyze pregnenolone sulfate. The cryptorchid state of exposure to 34 degrees C during 14 days decreased testis weight by 38 and 23%. But the enzymatic activity (nanomoles of free steroid/testis) was significantly higher (p < .05) compared with the control. Moreover, a rise in the environmental temperature combined with cryptorchidism in mice, two conditions that induced testicular damage, has been related to the elaboration of factors capable of modifying, through paracrine mechanism, the androgen biosynthesis. The presence of this factor could lead to an increase in the hydrolysis of pregnenolone sulfate, but as for cryptorchidism or high environmental temperature exposure, when cryptorchid mice were exposed to temperatures of 34 degrees C an apparent synergism of both conditions produced a decrease of 66% in testis weight. It would appear that the steroid sulfatase is predominantly located in the interstitial epithelium. This study suggests that cryptorchidism and hyperthermia damage the tubular epithelium by different mechanisms.

Hypothalamic monoamine oxidase activity in ovariectomized rats after sexual behavior restoration.

The effect of estradiol benzoate, progesterone and a sequential treatment with both on the activity of the enzyme monoamine-oxidase (MAO) was assessed in mitochondria from hypothalami of ovariectomized rats. A differential effect on the subtypes A and B MAO was found according to the type of treatment. Estradiol benzoate administration decreased MAO activity, mainly that of MAO-A. Progesterone alone had no effect, and sequential treatment with estradiol benzoate plus progesterone restored sexual behavior and produced a significant increase of MAO-A activity, without changes in total MAO activity. Since MAO-A is an isoform of MAO that preferentially uses norepinephrine and serotonin as substrates and MAO-B acts on phenylethylamine and benzylamine as substrates, our findings suggest that the restoration of sexual behavior after the treatment with estradiol benzoate followed by progesterone may be associated with the differential effect exerted by the hormones on MAO subtypes, rather than to the simple decrease in hypothalamic monoamine concentrations as reported in the literature.

Effectiveness of calcium and magnesium on testicular sulfatase activity.

Nucleotides and calcium ions have been implicated in the regulation of biosynthesis of steroids, although the exact locus of calcium activity is not yet known. The administration of Ca2+ to Leydig cells increases testosterone production. Steroid sulfatase activity is reported to be enhanced by adenine nucleotides. In the present study the testicular sulfatase was evaluated in subcellular fractions by conversion of sulfate to free steroids in the presence or absence of Ca2+ and Mg2+ ions. The specific activity of the enzyme, which was located predominantly in submitochondrial fraction, showed a positive correlation with calcium, increasing 1.5-fold in the presence of 2.54 mM of calcium (62 nmol/h mg protein-1). In contrast, magnesium inhibited the enzymatic activity 1.79-fold in presence of 1.18 mM (23 nmoles/h mg protein-1). It would appear that testicular sulfatase is predominantly located in the mitochondria, which is recognized as one of the major sites of control of intracellular metabolism, and that its enzymatic activity could be modulated by calcium regulating the levels of potentially active androgens.

Antiestrogen U23,469 induced alterations of catecholamine levels on plasma and central nervous system.

The effect of antiestrogen U23,469 administration in vivo on the concentration of dopamine, norepinephrine and epinephrine in the plasma, cerebral cortex and hypothalamus in ovariectomized rats was investigated. Rats were treated with estradiol benzoate, progesterone and U23,469 in different doses, s.c., daily for 6 days. Control group was injected with sesame oil. Catecholamines were estimated by radioenzymatic assay. Six days of U23,469, estradiol benzoate, progesterone or its combination altered the catecholamine levels compared to the control. Dopamine decreased in plasma with progesterone and U23,469. In the cerebral cortex, progesterone and U23,469 increased significantly and in the hypothalamus all the treatments produced a decrease of catecholamines. The levels of NE were reduced with estradiol benzoate, progesterone and U23,469; there was no significant difference in the norepinephrine levels after different treatments in the cerebral cortex, but the NE levels were significantly decreased in the hypothalamus. Epinephrine showed differences related to the treatment, as in plasma, as in cerebral cortex and hypothalamus. These results suggest that antiestrogen treatment compared with the estradiol benzoate or progesterone may affect the catecholamine levels of the central nervous system and plasma and support the idea that AE could have an indirect effect on the catecholaminergic system.

Sexual differences in the brain catecholamine content in four species of tropical bats.

The catecholamines dopamine, norepinephrine and epinephrine were studied in the brains of male and female tropical bats of four species, with different feeding habits (insectivorous, frugivorous, omnivorous and pollen eater). They were trapped in a refuge at 18 degrees 24'24''N, 99 degrees 02'08''W with a mean annual temperature of 25.8 degrees C, in a tropical deciduous forest. The three catecholamines occur in both sexes of all four species, in levels which are statistically different among species as well as between sexes. Dopamine and norepinephrine levels were higher in males than females, but the opposite occurs with epinephrine. These findings suggest that changes in catecholamine levels are intimately involved in the reproductive pattern of the species studied.

Influence of previous housing history on the toxicity of amphetamine in aggregate mice.

The lethality of d-amphetamine was studied in isolated and aggregated mice with and without previous habituation to the physical or to the physical and social environment of chronically aggregated social condition under which the toxic effects of d-amphetamine were tested. In animals without previous habituation to such environments, d-amphetamine's toxicity was greatly enhanced by social aggregation, as reported by several authors in the literature. It was found that mortality in the dose range from 5 to 90 mg/kg is mainly determined by the stimulation due to aggregation. Above 90 mg/kg, the mortalities in single and aggregated mice vary in parallel. Up from this dose, lethality is independent of the external stimulation. Previous experience with house sharing in aggregated conditions reduces aggregation mortality in proportion to the duration of the previous house sharing period.

Hypoglycaemia associated to vaginal insulin placement in rats.

The effect of vaginal placement of insulin was ascertained in rats by measuring plasma glucose levels. A rapid and sustained decrease of plasma glucose levels at 30, 60, 90 and 120 minutes after vaginal insulin administration was observed, returning to basal levels by 240 minutes. Thus, rapid insulin absorption was not curtailed by vaginal mucose. The effect was independent of the rat oestrous cycle phase.

Subneuronal fate of intracerebroventricular injected 3H-melatonin.

The fate of 3H-melatonin after its intracerebroventricular administration was studied both in different brain regions and in subcellular fractions. The rate of disappearance of 3H-melatonin from the brain was found to be multiphasic. Forty-eight h after a 3H-melatonin injection, radioactivity was still present in the brain. Nonlinear regression analysis of the data confirmed a very rapid half-life component and (t1/2 = 3.04 min) a slower one (t1/2 = 36 min). We also found a much slower component (t1/2 = 24 h), however. Considerable metabolism of melatonin was detected since only 36.5% of administered radioactivity remained as melatonin at 45 min. The subcellular distribution of the radioactivity present in the brain at all times studied showed that a major proportion of the radioactivity remained in the cytosol and respectively decreasing proportions in the 900g pellet, mitochondrial pellet, and the microsomes. The radioactivity remaining in the cytosol at 45 min was found to coelute with a macromolecule that was resolved by gel filtration and could be displaced by previous melatonin administration. Purified nuclei retained 0.71% of the radioactivity at 45 min; of this total, 73% was KCl extractable. Our data suggest the presence of a binding site in the cytosol and in the nucleus. The presence of 3H-melatonin up to 48 h after its administration may account for melatonin's long-term effects on brain function.

Presencia de aminas biogénicas en el líquido folicular y en el plasma seminal humano / Presence of biogenic amines in human follicular fluid and seminal plasma

Dopamine, norepinephrine, 5-hydroxytryptamine, and 5-hydroxyndoleacetic acid concentrations were measured in human seminal plasma and follicular fluid of healthy fertile individuals and in seminal plasma of azoospermic patients. All these substances were unevenly distributed in the male and female reproductive tract fluids. The highest monoamine (MA) concentration was observed for azoospermic seminal plasma followed by normal seminal plasma and follicular fluid. The differences in MA content were statistically significant. The occurrence of MA in human follicular fluid supports the suggestion of several authors that MA are involved in the regulation of the acquisition of the fertilizing ability of the sperm in female reproductive tract. However, the presence and uneven distribution of each MA in male and female fluids testify the complexity of the MA function in regulating the fertilizing ability spermatozoa

Comparative study of monoamine levels in discrete brain areas of five rodent species.

1. Dopamine, norepinephrine, serotonin and 5-hydroxyindol-acetic acid levels were studied in discrete brain areas of four wild rodent species and compared with those of laboratory mouse. 2. Monoamine levels showed significant differences in all the species studied. 3. Although it is not possible to exclude the changes induced by the captivity's stress, the results suggest that the natural hypoxic environment (high altitude) and/or the natural diet play an important role on the activity of the monoaminergic neurons. 4. Species which showed a better behavioral pattern of adaptation also showed significant differences in brain monoamine levels.

Brain monoamine oxidase activity after in vivo-chronic iprindole treatment.

The effects of chronic administration of three different doses of iprindole on the monoamine oxidase activity and neurotransmitter content were studied in the cerebral cortex, the mesencephalon and the cerebellum of mouse brain. The treatment inhibited mitochondrial monoamine oxidase activity of all three brain regions studied, although a dose-response inhibitory effect was found only in the mesencephalon. Brain regional serotonin contents were markedly increased after iprindole treatment. The 5-hydroxyindoleacetic acid contents showed a significant decrease only in the cerebral cortex. Neither dopamine nor norepinephrine brain regional contents were significantly altered. On the basis of these results it is suggested that a substrate-specific inhibition of monoamine oxidase is involved in the mechanism of action of this tricyclic antidepressant.