The metabolic clearance rate, head and brain extractions, and brain distribution and metabolism of progesterone in the anesthetized, female monkey (Macaca mulatta)

5alpha-dihydroprogesterone promotes proliferation and migration of human glioblastoma cells

Glioblastomas (GBMs) are the most common and deadliest intracranial tumors. Steroid hormones, such as progesterone (P4), at physiological concentrations, promote proliferation, and migration of human GBM cells in vivo and in vitro. Neuronal and glial cells, but also GBMs, metabolize P4 and synthesize different active metabolites such as 5α-dihydroprogesterone (5α-DHP). However, their contribution to GBM malignancy remains unknown. Here, we determined the 5α-DHP effects on the number of cells, proliferation, and migration of the U87 and U251 human GBM-derived cell lines. Of the tested concentrations (1 nM-1 µM), 5α-DHP 10 nM significantly increased the number of U87 and U251 cells from day 2 of treatment, and proliferation (at day 3) in a similar manner as P4 (10 nM). The treatment with the progesterone receptor (PR) antagonist RU486 (mifepristone), blocked the effects of 5α-DHP on the number of cells and proliferation. Besides, in U251 and LN229 GBM cells, 5α-DHP promoted cell migration (from 12 to 24 h). We also determined that GBM cells expressed the 3α-hydroxysteroid oxidoreductases (3α-HSOR), which reversibly reduce 5α-DHP to allopregnanolone (3α-THP). These data indicate that 5α-DHP induces proliferation and migration of human GBM through the activation of PR.

Neurosteroids and Seizure Activity

Still circa 25% to 30% of patients with epilepsy cannot be efficiently controlled with available antiepileptic drugs so newer pharmacological treatment options have been continuously searched for. In this context, a group of endogenous or exogenous neurosteroids allosterically positively modulating GABA-A receptors may offer a promising approach. Among endogenous neurosteroids synthesized in the brain, allopregnanolone or allotetrahydrodeoxycorticosterone have been documented to exert anticonvulsant activity in a number of experimental models of seizures-pentylenetetrazol-, bicuculline- pilocarpine-, or 6 Hz-induced convulsions in rodents. Neurosteroids can also inhibit fully kindled seizures and some of them have been reported to counteract maximal electroshock-induced convulsions. An exogenous neurosteroid, alphaxalone, significantly elevated the threshold for maximal electroconvulsions in mice but it did not potentiate the anticonvulsive action of a number of conventional antiepileptic drugs against maximal electroshock-induced seizures. Androsterone not only elevated the threshold but significantly enhanced the protective action of carbamazepine, gabapentin and phenobarbital against maximal electroshock in mice, as well. Ganaxolone (a 3beta-methylated analog of allopregnanolone) needs special consideration for two reasons. First, it performed better than conventional antiepileptic drugs, diazepam or valproate, in suppressing convulsive and lethal effects of pentylenetetrazol in pentylenetetrazol-kindled mice. Second, ganaxolone has been evaluated in the randomized, double-blind, placebo-controlled phase 2 trial in patients with intractable partial seizures, taking maximally 3 antiepileptic drugs. The initial results indicate that add-on therapy with ganaxolone resulted in reduced seizure frequency with adverse effect being mainly mild to moderate. Possibly, ganaxolone may be also considered against catamenial seizures. Some positive effects of ganaxolone as an adjuvant were also observed in children with refractory seizures and its use may also prove efficient for the management of neonatal seizures associated with hypoxic injury. Neurosteroids positively modulating GABA-A receptor complex exert anticonvulsive activity in many experimental models of seizures. Their interactions with antiepileptic drugs seem ambiguous in mice. Initial clinical data indicate that ganaxolone may provide a better seizure control in patients with drug-resistant epilepsy.

A Tribute to Dr Robert J. White

Robert J. White is probably best known as the first neurosurgeon to perform successful "cephalic exchange" on monkeys in 1971. However, he was also a pioneer in the field of neurosurgery and contributed tremendously to the field of neuroanesthesia and bioethics. White received medical training at the University of Minnesota, Harvard University, Peter Bent Brigham Hospital, and Mayo Clinic before becoming the first Chief of Neurosurgery at Metrohealth Hospital in Cleveland, Ohio. He made significant strides in the field of spinal cord cooling and hypothermia. White and his team was also the first to successfully isolate the monkey brain with retention of biological activity. In 2004 and 2006, White and colleagues were nominated for the Nobel Prize in Physiology and Medicine, with Harvey Cushing and Wilder Penfield being the only other 2 neurosurgeons ever to be nominated for the award. Aside from his career as a neurosurgeon, he was also an advisor to 2 popes and an advocate for animal research. By the end of his career, White performed over 10 000 brain operations and published over 1000 articles, which has pushed the frontiers of neurosurgical research.

From Hypothermia to Cephalosomatic Anastomoses: The Legacy of Robert White (1926-2010) at Case Western Reserve University of Cleveland

Dr. Robert J. White (1926-2010) was an eminent neurosurgeon and bioethicist, renowned for his classic work in hypothermia and pioneering mammalian head transplant experiments. He founded the Division of Neurosurgery at the Cleveland Metropolitan General Hospital (currently MetroHealth Medical Center, a level 1 trauma county hospital) and became the youngest full professor at the Case Western Reserve University in Cleveland, Ohio. With over 500 research articles to his credit, he founded the Brain Research Laboratory at what was then the Cleveland Metropolitan General Hospital, which was also home to future leaders in neurosurgery, neurosciences, and allied specialties. He transferred a healthy monkey head onto a surgically beheaded monkey body under deep hypothermic conditions drawing both laurels and criticisms alike. Despite a largely controversial neurosurgical research career, his original contributions to deep hypothermia have found profound clinical applications in modern trauma and vascular neurosurgery. The new fusogens and myelorrhaphy methods being tried in Europe hold promise for a future of reanastomosing 2 homologous or heterologous tracts in the neuraxis.

Progesterone pharmacokinetics in the mouse: implications for potential stroke therapy

OBJECTIVES

Progesterone has been shown to be neuroprotective in a number of preclinical central nervous system injury models including cerebral ischaemia. The aim of this study was to clarify differences in outcomes owing to different dosing regimens and the pharmacokinetic profile of progesterone, particularly in relation to brain levels.

METHODS

Male C57 Bl/6 mice were injected intraperitoneally with progesterone (8 mg/kg in dimethylsulfoxide) or with a bolus injection followed by continuous subcutaneous infusion (1.0 µl/h of a 50 mg/ml progesterone solution) via implanted osmotic minipumps. Plasma and brain samples were collected over 24 h from bolus-injected mice and 48 h from mice implanted with minipumps. Progesterone concentrations were measured by an enzyme-linked immunoassay and pharmacokinetic profiles were constructed.

KEY FINDINGS

Intraperitoneally injected progesterone had a short half-life (fast component half-life of 0.2 h) in both plasma and brain. Minipump delivery resulted in higher concentrations of progesterone in plasma and particularly in brain over a longer period. The volume of distribution with intraperitoneal injection was 172.78 versus 1641.84 ng/h per g via minipump in the first 24 h.

CONCLUSIONS

A bolus intraperitoneal loading dose of progesterone followed by continuous delivery via osmotic minipump is an effective way of delivering progesterone to the brain.

Effect of short-and long-term gonadectomy on neuroactive steroid levels in the central and peripheral nervous system of male and female rats

Significant levels of neuroactive steroids are still detected in the nervous system of rodents after the removal of peripheral steroidogenic glands. However, the influence of the plasma levels of gonadal steroids on the levels of neuroactive steroids in the nervous system has not so far been clarified in detail. Accordingly, by liquid chromatography tandem mass spectrometry, we have analysed the levels of neuroactive steroids in the sciatic nerve, in three central nervous system (CNS) regions (i.e. cerebellum, cerebral cortex and spinal cord) and in the plasma of male and female animals. The levels present in gonadally intact animals were compared with those present in short- and long-term gonadectomised animals. We observed that: (i) changes in neuroactive steroid levels in the nervous system after gonadectomy do not necessarily reflect the changes in plasma levels; (ii) long-term gonadectomy induces changes in the levels of neuroactive steroids in the peripheral nervous system (PNS) and the CNS that, in some cases, are different to those induced by short-term gonadectomy; (iii) the effect of gonadectomy on neuroactive steroid levels is different between the PNS and the CNS and within different CNS regions; and (iv) the effects of gonadectomy on neuroactive steroid levels in the nervous system show sex differences. Altogether, these observations indicate that the nervous system adapts its local levels of neuroactive steroids in response to changes in gonadal hormones with sex and regional specificity and depending on the duration of the peripheral modifications.

Sex differences in neuroactive steroid levels in the nervous system of diabetic and non-diabetic rats

Neuropathy and encephalopathy represent important complications of diabetes. Recent observations obtained in experimental models have suggested that, in male rats, neuroactive steroids are protective agents and that their levels in peripheral (PNS) and central (CNS) nervous system are strongly affected by the disease. It is interesting to highlight that incidence, progression and severity of diabetic neuropathy and diabetic encephalopathy are different in the two sexes. Consequently, it is important to determine the changes in neuroactive steroid levels in the PNS and the CNS of both males and females. To this aim, we have evaluated the levels of neuroactive steroids such as, pregnenolone, progesterone and its metabolites, testosterone and its metabolites, and dehydroepiandrosterone in different CNS regions (i.e., cerebral cortex, cerebellum and spinal cord) and in the sciatic nerve of control and diabetic (i.e., induced by streptozotocin) male and female rats. Data obtained by liquid chromatography-tandem mass spectrometry indicate that the levels of neuroactive steroids show sex and regional differences in control animals. Streptozotocin-induced diabetes resulted in a strong general decrease in neuroactive steroid levels, in both the PNS and the CNS. In addition, the effects of diabetes on neuroactive steroid levels also show sex and regional differences. These findings may have strong implications for the development of new sex-oriented therapies for the treatment of diabetic neuropathy and diabetic encephalopathy, based on the use of neuroactive steroids.

Steroid profiling in brain and plasma of male and pseudopregnant female rats after traumatic brain injury: analysis by gas chromatography/mass spectrometry

Steroids in brain arise from the peripheral endocrine glands and local synthesis. In traumatic brain injury (TBI), the endogenous circulating hormones at the time of injury are important for neuroprotection. In particular, pseudopregnant females recover better than males from TBI. We investigated the effect of pseudopregnancy and TBI on steroid levels in plasma and in three brain regions (within, adjacent, and distal to the lesion site), 6 and 24 h after prefrontal cortex injury. The following steroids were analyzed by gas chromatography/mass spectrometry: pregnenolone, progesterone, 5alpha-dihydroprogesterone, 3alpha,5alpha-tetrahydroprogesterone, 3beta,5alpha-tetrahydroprogesterone, dehydroepiandrosterone, Delta(4)-androstenedione, testosterone, 5alpha-dihydrotestosterone, 3alpha,5alpha-tetrahydrotestosterone, 3beta,5alpha-tetrahydrotestosterone, and 17beta-estradiol. Corticosterone was assayed in plasma to account for stress in the rats. We found different steroid profiles in brain and plasma of male and pseudopregnant female rats and specific profile changes after TBI. In sham-operated pseudopregnant females, much higher levels of progesterone, 5alpha-dihydroprogesterone, 3alpha,5alpha-tetrahydroprogesterone, and 3beta,5alpha-tetrahydroprogesterone were measured in both brain and plasma, compared with sham-operated males. Plasma levels of corticosterone were high in all groups, indicating that the surgeries induced acute stress. Six hours after TBI, the levels of pregnenolone, progesterone, and 5alpha-dihydroprogesterone increased, and those of testosterone decreased in male brain, whereas levels of 5alpha-dihydroprogesterone and 3beta,5alpha-tetrahydroprogesterone increased in brain of pseudopregnant female rats. Plasma levels of 5alpha-dihydroprogesterone did not change after TBI, suggesting a local activation of the 5alpha-reduction pathway of progesterone in both male and pseudopregnant female brain. The significant increase in neurosteroid levels in the male brain after TBI is consistent with their role in neuroprotection. In pseudopregnant females, high levels of circulating progestagens may provide protection against TBI.

The Brain Research Laboratory at the Cleveland Metropolitan General Hospital and case Western Reserve University

In 1961 Dr. Robert White, fresh from the Mayo Clinic, established the Brain Research Laboratory (BRL) at the Cleveland Metropolitan General Hospital, Cleveland, Ohio, under the auspices of Case Western Reserve University. During a span of 15 years, he and his colleagues contributed significantly to our knowledge and understanding of the central nervous system in deep hypothermic conditions, thus demonstrating the protective effects of cerebral and spinal cord cooling in patients with injuries as well as the ability of the brain to survive extended periods of total circulatory arrest at extremely low temperatures. It was there that isolated brain preparation and transplantation were first accomplished. These and other unique, surgically constructed brain models opened new fields of exploration in neurochemical, neurophysiological, rheological, immunological, and cognitive features of the brain in normothermic and various hypothermic states. During the laboratory's most productive years (1961-1976), there were 10 surgeons actively involved in scientific investigations who later became chairmen or chiefs of Departments or Divisions of Neurosurgery and another four who became professors of neurosurgery or other surgical specialties.

Neuroactive steroids and central nervous system disorders

Steroid hormones are vital for the cell life and affect a number of neuroendocrine and behavioral functions. In contrast to their endocrine actions, certain steroids have been shown to rapidly alter brain excitability and to produce behavioral effects within seconds to minutes. In this article we direct attention to this issue of neuroactive steroids by outlining several aspects of current interest in the field of steroid research. Recent advances in the neurobiology of neuroactive are described along with the impact of advances on drug design for central nervous system (CNS) disorders provoked by neuroactive steriods. The theme was selected in association with the clinical aspects and therapeutical potentials of the neuroactive steroids in CNS disorders. A wide range of topics relating to the neuroactive steroids are outlined, including steroid concentrations in the brain, premenstrual syndrome, estrogen and Alzheimer's disease, side effects of oral contraceptives, mental disorder in menopause, hormone replacement therapy, Catamenial epilepsy, and neuractive steroids in epilepsy treatment.

Psychoneuroendocrine aspects of temporolimbic epilepsy. Part II: Epilepsy and reproductive steroids

Reproductive dysfunction is unusually common among men and women with epilepsy. Reproductive endocrine disorders are also common and may be causal. The association between particular reproductive endocrine disorders and the laterality and focality of epileptiform discharges suggests an etiologic role for epilepsy. Gonadal steroids are neuroactive and influence seizure occurrence: estrogen is epileptogenic whereas progesterone has antiseizure effects. Fluctuations in the absolute and relative serum levels of these hormones may play a critical role in establishing three distinct patterns of catamenial epilepsy: 1) perimenstrual and 2) preovulatory in women with ovulatory cycles, and 3) entire luteal phase of the cycle in women with anovulatory cycles. Treatment with progesterone reduces seizure frequency by more than half. In men, testosterone effects may depend on the relative concentrations of two major testosterone metabolites that exert opposing influences on neuronal excitability: estrogen potentiates whereas dihydrotestosterone inhibits NMDA-mediated conductance. Combined therapy using an aromatase inhibitor along with testosterone improves sexual function and may reduce seizures in men with epilepsy.

Sex steroids and libido

The effects of steroidal hormones on sexual desire and motivation are a question still under debate. This paper reviews up-to-date knowledge regarding physiological imprinting and activation by endogenous hormones of central nervous system areas involved in libido during intrauterine life and puberty. The endocrine environment probably continues to play a role during fertile life and the postmenopausal period, but this effect is often overridden by psychological and social factors. The impairment of sexual interest during estrogen-progestin treatment is an infrequent but relevant side-effect whose possible underlying mechanisms are discussed. Both endocrine and psychorelational elements may interact. From the biological point of view, androgen and oxytocin level modification and loss of estrogen fluctuations have been considered, but also the history of hormone-related mood changes could be a risk factor. On the psychological side, both the profound repercussions of the contraceptive choice and consequent responsibility, as well as the high value attributed to sexual experience are probably facilitating elements in the loss of libido under treatment.

Progesterone, 5alpha-pregnane-3,20-dione and 3alpha-hydroxy-5alpha-pregnane-20-one in specific regions of the human female brain in different endocrine states

Post-mortem concentrations of progesterone, 5alpha-pregnane-3,20-dione (5alpha-DHP) and 3alpha-hydroxy-5alpha-pregnane-20-one (allopregnanolone) were measured in 17 brain areas and serum in five fertile and five postmenopausal women. Steroid concentrations were measured with radioimmunoassay after extraction of brain tissue with ethanol and purification with celite chromatography. There were regional differences in brain concentrations of all three steroids. The highest progesterone levels were noted in the amygdala, cerebellum and hypothalamus and the highest levels of 5alpha-DHP and allopregnanolone were seen in the substantia nigra and basal hypothalamus. Brain concentrations of all three steroids were significantly higher in the fertile women in luteal phase compared to their postmenopausal controls (P < 0.01). In general, the study showed that there is a variation in brain concentrations depending on ovarian steroid production, indicating that the secretion pattern during the menstrual cycle is reflected in the brain. However, regional differences in brain steroid levels imply local mechanisms for steroid uptake and binding as well. Investigations of gonadal steroid distributions in the human brain might be of importance considering the actions of these steroids in the central nervous system. Such studies could provide information about physiological mechanisms, such as the ovulation, and also form a baseline for comparative studies of normal and pathological conditions involving steroids, for instance, catamenial epilepsy and the premenstrual tension syndrome.

Regional distribution of progesterone and 5 alpha-pregnane-3,20-dione in rat brain during progesterone-induced "anesthesia"

Progesterone and 5 alpha-pregnane-3,20-dione (5 alpha-DHP) concentrations were measured in seven brain areas and in plasma during "anesthesia" induced by progesterone (1-2 mg IV) in female rats. The highest levels of progesterone were detected in the striatum and hypothalamus (23.3 +/- 5.27 and 22.7 +/- 4.30 micrograms/g +/- SEM, respectively); these concentrations were approximately 1000 times higher than those during the post-ovulatory phase. Highest levels of 5 alpha-DHP were detected in the striatum and hippocampus (11.5 +/- 1.74 and 10.4 +/- 3.15 micrograms/g +/- SEM, respectively). The ratio of 5 alpha-DHP to progesterone was approximately 100 times higher in brain tissue than in plasma. We conclude that a conversion of progesterone to 5 alpha-DHP occurs in the brain during the course of progesterone-induced "anesthesia". This metabolic step may be an important contributory factor to the anesthetic potency of progesterone.

Climacteric complaints as influenced by progestogens

A general assessment of the usefulness of progestogens in the treatment of climacteric complaints is made, based on evidence from the literature. The effects of progestogens in regard to vasomotor and mental symptoms are considered separately.

Epilepsy, sex hormones, and antiepileptic drugs

Many factors associated with hormone function have an impact on the course of epilepsy. Patients with epilepsy may have disturbances in sexual function such as anovulatory cycles in women and decreased libido and potency in men. Data indicate seizures, especially those arising in the limbic system, may influence the hypothalamic pituitary axis. Antiepileptic drugs also influence sexual function through direct brain effects as well as through induced changes in pharmacokinetics of the sex steroid hormones. Pregnancy has been reported to be a time of increased seizures; however, this has often been associated with low drug levels, for reasons that include inadequate drug dose, possible changes in pharmacokinetics, and noncompliance. Some evidence suggests that hormones affect seizure frequency. Changes in seizures during the menstrual cycle (catamenial epilepsy) have been found in some women: seizures were fewer during the luteal phase but increased when progesterone levels declined. Some improvement in seizure frequency has been shown in pilot studies using medroxyprogesterone acetate, a synthetic progesterone. Current concepts of the interrelationship among epilepsy, sex hormones, and antiepileptic drugs are discussed.

Uterine metabolism of gonadal steroids during the menstrual cycle

The metabolic clearance rate and uterine extraction of (3H)progesterone, (3H)estradiol, and (14C)estrone were studied at the time of hysterectomy in six women on or before day 12 of the menstrual cycle, in three women after day 12, and in one postmenopausal woman. The metabolic clearance rates of progesterone, estradiol, and estrone were in the same range as for normal women as previously reported by us. The uterine extraction for progesterone ranged between 12% and 37% on or before day 12 and 0% to 5% after day 12, and was 7.4% in the postmenopausal woman. The uterine extraction of estradiol was 0% to 25% on or before day 12, and 0%, 4%, and 22% after day 12 and was 18% in the postmenopausal woman. The uterine extraction of estrone was 7% to 24.5% on or before day 12 and 0% after day 12 and was 18% in the postmenopausal woman. The across-uterine interconversion of estradiol to estrone was 0% to 2.7% and of estrone to estradiol 0% to 2.6%. Both conversions appeared to be independent of the day of the menstrual cycle. The results suggest that the uterine metabolism of progesterone and estrone and perhaps estradiol is lower in the luteal phase of the cycle as compared to the follicular phase and that the conversion of estradiol to estrone may not be a major reaction of estradiol metabolism in the human uterus.

The head extractions, brain and pituitary uptake and metabolism of progesterone and 5alpha-dihydroprogesterone in anesthetized, female rabbits

Three days after ovariectomy adult female rabbits were injected intramuscularly with either 2 mug estradiol/kg b.w., 0.5 mg progesterone/kg b.w., 2 mug estradiol plus 0.5 mg progesterone/kg b.w., or oil vehicle daily for 5 days. On the sixth day the animals were anesthetized and given a continuous infusion of [14C]progesterone and [3H]5alpha-pregnane-3,20-dione (5alpha-DHP) for 4 h via the femoral vein. Head extractions, calculated from the difference in blood concentrations of radioactive steriods between the femoral artery and jugular vein, were in the range of 60-75% for both progesterone and 5alpha-DHP and were unaffected by the hormone treatments. Nine brain areas and the pituitary were analyzed for [14C]progesterone, [3H]5alpha-DHP and [14C]-5alpha-DHP. Generally, the brain and pituitary retention and distribution of [14C]progesterone and [3H]5alpha-DHP and the brain and pituitary metabolism of [14C]progesterone were unaffected by hormone treatments. In the cerebellum, progesterone treatment increased [14C]progesterone retention as compared to oil treatment. All tissues contained 2-7 times more [14C]progesterone than arterial blood concentrations. [3H]5alpha-DHP tissue: arterial blood concentrations ratios were much lower ranging from 0.9 to 1.78. [14C]progesterone and [3H]5alpha-DHP showed similar brain distribution with highest concentrations in the pons, pons reticulum and midbrain reticulum. All tissues converted progesterone to 5alpha-DHP, but only the cerebellum contained more [14C]5alpha-DHP than [14C]progesterone.

In vivo aspects of progesterone distribution and metabolism

The end-organ response of any hormone is the result of many factors which precede the event, including biosynthesis, secretion, transport, distribution, and metabolism. These factors vary among different species. The metabolic clearance rate (MCR) of progesterone varies between 40 and 180 L./day/Kg. in man (60 to 70), monkey (40 to 50), rabbit (55 to 60), sheep (110), rat (120), and guinea pig (180). Major sites of clearance include liver, brain, and uterus. Specific metabolites of progesterone include 20 alpha-hydroxypregn-4-en-3-one (20 alphaOHP) and alpha-pregnan-3,20-dione (5 alpha-DPH). Liver, brain, and uterine clearances, extractions, and conversions of progesterone to these metabolites have been studied in various species under apparent steady-state conditions. A specific hormone action of progesterone, the appearance of uteroglobin in the rabbit uterus, has also been studied in varying horomonal states (estrogen, estrogen plus progesterone, and progesterone alone). These have all been used as examples of progesterone distribution and metabolism.