Differential distribution of the 5-alpha-reductase in the central nervous system of the rat and the mouse: are the white matter structures of the brain target tissue for testosterone action?

In the brain of several animal species testosterone is converted into a series of 5-alpha-reduced metabolites, and especially into 17-beta-hydroxy-5-alpha-androstan-3-one (DHT), by the action of the enzyme 5-alpha-reductase. The formation of DHT has never been evaluated in the white matter structures of the brain, which are composed mainly of myelinated axons. The experiments here described were performed in order to study, in the rat and the mouse, the DHT forming activity of several white matter structures, in comparison with that of the cerebral cortex and of the hypothalamus.

Circatrigintan rectal temperature and endocrine rhythms of clinically healthy, menstrually cycling women.

Rectal temperatures were measured automatically every 10 min for part or most of two menstrual cycles in ten clinically healthy young women, 20-30 years of age, with a wearable instrument, the Polychronor. Occasional malfunction of the instrumentation resulted in corresponding gaps in the series. Data were examined by chronograms, plexograms, and chronobiologic serial sections computed with the fit of a 24-hr period, population-mean cosinor, and linear-nonlinear least-squares analyses.

[Human leptospirosis in New Caledonia and dependencies. Apropos of 57 cases observed between 1 June 1983 and 31 May 1985].

57 cases of leptospirosis were diagnosed in New Caledonia (South Pacific French Territory) between June 1983 and May 1985. 25% cases are severe infections; thrombopenia and renal failure are frequently observed. Leptospires are found in blood or spinal or urine culture confirmed by haemagglutination tests on microplates (Martin et Petit).

[A severe form of external otitis: necrosing diabetic otitis].

Otitis externa are of usual observation in inter-tropical regions. Pseudomonas aeruginosa is responsible generally. But, when immunodeficiency is associated or on diabetic diathesis, such an otitis externa can be extremely dangerous: extensive osteitis of the base of the skull, paralysis of the last pairs of cervical nerves rapidly creeping, built a clinical identity called malignant external otitis, leading to death in 50% of the cases.

In vitro release of luteinizing hormone-releasing hormone from the hypothalamus of old male rats.

The present experiments tested the ability of the hypothalamus of old male rats to release LHRH in vitro. Mediobasal hypothalami (MBH) of 18-month-old and 6-month-old male rats were perfused for a total of 5 h and 5 min; the amounts of LHRH released, both in basal conditions and after stimulation with high extracellular K+ (110 mM, applied for 5 min every 30 min), were measured in the effluent. Our results show that the basal secretion of LHRH from the perfused MBH of young and old male rats is quantitatively similar.

Gonadal steroid modulation of brain opioid systems.

It is becoming increasingly clear that the effects of the opioids and their synthetic analogs on anterior pituitary function largely depend on the steroid milieu present in the animal at time of drug administration. However, it is still unclear whether gonadal steroids regulate the opioid-modulated mechanisms by affecting the number of opiate receptors in the brain. To further investigate these issues, the effects of opiate agonists and antagonists on LH, FSH and prolactin (Prl) secretion have been studied in: (a) normal and castrated male rats, and (b) normally cycling female rats.

New approaches for the treatment of prostatic hypertrophy and cancer.

The present study reports the effects exerted by 4-hydroxy-4-androstene-3,17-dione (4-OH-A) on the in vitro metabolism of labelled testosterone, dihydrotestosterone (DHT) and androstenedione (delta-4-A) in the prostate of adult male rats and in human benign prostatic hypertrophic (BPH) tissue. It has been found that 4-OH-A decreases the formation of DHT and of the diols. When testosterone is used as the substrate, the presence in the medium of 4-OH-A enhances the formation of delta-4-A and of 5-alpha-androstanedione (5-alpha-A); 4-OH-A does not inhibit the conversion of labelled DHT into the diols.

In vitro metabolism of testosterone in the rat prostate: influence of aging.

The in vitro metabolism of labelled testosterone has been studied in the ventral prostate of young (2 months) and old (15 and 22 months) male rats. It has been found that the prostate of 2-month old animals converts testosterone into dihydrotestosterone (5-alpha-androstane-17-beta-ol-3-one, DHT) and into the diols (5-alpha-androstane-3-alpha,-17-beta-diol and 5-alpha-androstane-3-beta,17-beta-diol) with considerable yields. The prostate of young animals is also able to convert testosterone into delta-4-androstenedione (delta-4-A), 5-alpha-androstanedione (5-alpha-A) and androsterone (A); however, the amount of these metabolites are lower than those of DHT and the diols.

Effect of 1,4,6-androstatriene-3,17-dione (ATD), 4-hydroxy-4-androstene-3,17-dione (4-OH-A) and 4-acetoxy-4-androstene-3,17-dione (4-Ac-A) on the 5 alpha-reduction of androgens in the rat prostate.

The present study reports the effects exerted by 1,4,6-androstatriene-3,17-dione (ATD), 4-hydroxy-4-androstene-3,17-dione (4-OH-A) and 4-acetoxy-4-androstene-3,17-dione (4-Ac-A), three steroids known to inhibit the aromatization of androgens to estrogens, on the in vitro metabolism of labelled testosterone (T), dihydrotestosterone (DHT) and androstenedione (delta-4-A) in the ventral prostate of adult male rats. It has been found that ATD, in the concentration tested, does not influence the conversion of labelled T into DHT, but decreases the formation of 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol (diols). On the contrary, 4-OH-A and 4-Ac-A simultaneously decrease the formation of DHT and the diols.

In vitro effects of an aromatase inhibitor on 5 alpha-reductase activity in human hypertrophic prostatic tissue.

To determine the effects of 4-hydroxy-4-androstene-3,17-dione (4-OH-A) on the in vitro conversion of testosterone (T) to 5 alpha-androstan-17 beta-ol-3-one (dihydrotestosterone, DHT), 5 alpha-androstan-3 alpha, 17 beta-diol and 5 alpha-androstan-3 beta, 17 beta-diol (diols), human benign hypertrophic prostatic (BPH) tissue was incubated with 4-14C-T as substrate, in the presence of 4-OH-A (10(-8) to 10(-6) M); the amounts of the 5 alpha-reduced metabolites formed were quantitated. The effects of 4-OH-A were compared with those of 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one (4-MA), a known inhibitor of the 5 alpha-reductase. In the absence of 4-OH-A and 4-MA, human BPH tissue converted T to DHT and the diols readily.

Morphine stimulates prolactin release in normal but not in castrated male rats.

Morphine (200 micrograms/rat) was injected intraventricularly (i.v.t.

[Neurologic manifestations of ciguatera. 3 cases with a neurophysiologic study and examination of one nerve biopsy].

Ciguatera is the commonest form of poisoning resulting from eating fish in the tropics. It has been recognised since the 15th century. The disease is due to the formation of ciguatoxin by a dinoflagellate, Gambierdiscus toxicus, loosely attached to algae growing on coral reefs.

Studies on the possible existence of two 5 alpha-reductases in the rat prostate.

In the first group of experiments, the in vitro metabolism of labelled testosterone has been studied in the ventral prostate of young (2 months) and old (15 and 22 months) male rats. It has been found that the prostate of 2-month-old animals converts testosterone into dihydrotestosterone (5 alpha-androstane-17 beta-ol-3 one, DHT) and into the diols (5 alpha-androstane-3 alpha-17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol) with considerable yields. The prostate of young animals is also able to convert testosterone into delta 4-androstenedione (delta 4-A), 5 alpha-androstanedione (5 alpha-A) and androsterone (A); however, the amounts of these metabolites are lower than those of DHT and the diols.

Stimulatory and inhibitory effects of the opioids on gonadotropin secretion.

In order to gain additional information on the role played by the opioids in the control of the secretion of anterior pituitary gonadotropins, morphine (an opioid agonist) and naloxone (an opioid antagonist) have been injected intraventricularly (i.v.t.

Effect of naloxone on luteinizing hormone, follicle-stimulating hormone, and prolactin secretion in the different phases of the estrous cycle.

It is becoming increasingly clear that the effects exerted by opioid agonists and antagonists on the release of gonadotropins and of PRL may vary according to the endocrine milieu. To investigate this issue further, female rats with a regular 4-day estrous cycle have been injected sc with the opioid antagonist naloxone at different hours of the day, during each of the various days of the estrous cycle. The animals were killed 20 min after the sc administration of naloxone (2.

Progress in chronophysiology of peptide hormones with emphasis on clinical application of analogues.

It is now established that peptide hormones are among the most versatile substances involved in intercellular communications. By substitution of one or more natural aminoacids, numerous peptide analogues have been synthesized with increased duration of action and potency with respect to endogenous hormones. Most of these effects are programmable as a function of dose and timing of administration.

Testosterone 5 alpha-reductase in discrete hypothalamic nuclear areas in the rat: effect of castration.

The conversion of testosterone into 5 alpha-dihydrotestosterone (DHT) has been studied in different hypothalamic nuclear areas and in the superficial layers of the cerebral cortex of normal and castrated male rats. The tissue fragments utilized in each incubation have been punched from frozen brain sections utilizing calibrated needles. Castration has been performed 12 (short term) and 180 (long term) days before sacrifice.

Induction of precocious puberty in the female rat after chronic naloxone administration during the neonatal period: the opiate 'brake' on prepubertal gonadotrophin secretion.

Studies were undertaken using the opiate receptor antagonist naloxone to examine the hypothesis that endogenous opiates may have a restraining effect on prepubertal gonadotrophin secretion and may be involved in the maturation of the central nervous system mechanisms regulating the onset of puberty in the female rat. Naloxone (2.5 mg/kg) administered intraperitoneally every 6 h to female rats from day 1 to day 10 of postnatal life significantly (P less than 0.