Electrical status epilepticus in slow wave sleep: prospective case study of a cortical hearing impairment.

The development of a central hearing impairment is described in a young girl with risk factors for hearing impairment that included mosaic Down syndrome, leukemia, and chemotherapy. This case is unusual in the prospective regularity with which hearing was assessed from birth. The diagnosis is electrical status epilepticus in slow wave sleep, a rare childhood disorder, which was associated with lack of responsiveness to auditory signals, regression of emerging speech and language and other cognitive skills, and abnormal electroencephalographic (EEG) activity in both hemispheres. Treatment of the disorder with anticonvulsant medications and steroids has ameliorated the condition by suppressing the abnormal EEG activity and allowing substantial improvements in cognitive and social skills, although communication skills are improving more slowly.

Melatonin treatment affects the attractiveness of the anogenital area scent in meadow voles (Microtus pennsylvanicus).

Seasonal differences exist in the attractiveness of scents in meadow voles, Microtus pennsylvanicus. To determine whether photoperiodically induced changes in the attractiveness of a sex-specific scent is governed by melatonin, we implanted long-photoperiod male and female scent donors with a Silastic implant containing a 10-mm active length of melatonin, a 20-mm active length of melatonin, or no melatonin. The first experiment shows that 8 weeks of melatonin treatment is sufficient to induce long-photoperiod voles to produce scents that are no longer attractive to the opposite sex. The second experiment shows that a similar time course of melatonin treatment was sufficient to induce long-photoperiod females treated with melatonin to produce scents that are attractive to short-photoperiod females. Melatonin implants lowered the gonadal hormone titers and reduced the weight of the gonads of treated long-photoperiod voles to titers and weights that are characteristic of short-photoperiod voles. In both experiments, the behavioral and physiological effects were independent of whether scent donors received 10- or 20-mm implants of melatonin. Together, the results of the two experiments reveal that melatonin mediates the photoperiodically induced changes in gonadal hormone titers that control the seasonal differences in the sexual attractiveness of the anogenital area scent produced by meadow voles.

Differential secretion of follicle-stimulating hormone and luteinizing hormone from ovine pituitary cells following activation of protein kinase A, protein kinase C, or increased intracellular calcium.

A higher dose of GnRH is required to stimulate release of FSH than of LH, both in vivo and in vitro. Therefore, we tested the hypothesis that secretion of FSH may be mediated via a second messenger pathway different from the one that modulates secretion of LH. Pituitary cells from intact ewes were cultured in suspension in DMEM plus 10% wether serum. After 18 h, cell were washed and challenged for 2 h with agents capable of activating protein kinase A (dibutyryl cAMP), protein kinase C (phorbol 12-myristate 13-acetate; PMA), or increasing intracellular calcium (the calcium ionophore A23187). GnRH (0.01-10 nM) and PMA (0.2-20 nM) stimulated dose-dependent increases in secretion of LH. FSH secretion also was stimulated by GnRH and PMA; however, the percentage of total cellular FSH released was lower (p < 0.05) than the percentage of total cellular LH released. Dibutyryl cAMP (10 mM) induced a modest release (p < 0.05) of both LH and FSH. A23187 (1-10 microM) stimulated secretion of LH in a dose-dependent manner but did not influence secretion of FSH; however, GnRH- and PMA-induced secretion of FSH required the presence of intracellular calcium. On the basis of the results of this study, we suggest that secretion of FSH is less than secretion of LH following direct activation of these second messenger systems. Furthermore, we suggest that in contrast to the situation for LH, increased intracellular calcium is not the primary stimulus for inducing secretion of FSH.

Regulation of messenger ribonucleic acid encoding 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase in the ovine corpus luteum.

Three experiments were conducted to determine how steady-state levels of mRNA encoding 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) in the ovine corpus luteum vary 1) between the two steroidogenic luteal cell types, 2) during the estrous cycle, and 3) during prostaglandin F2 alpha (PGF2 alpha)-induced luteolysis. In the first experiment, RNA (10 micrograms) was isolated from purified preparations (n = 4) of large or small steroidogenic luteal cells. Large luteal cells contained 42% more (p < 0.05) message for 3 beta-HSD per microgram RNA than did small luteal cells, while the amount of mRNA for tubulin did not differ between the two types of luteal cells. To determine whether luteal levels of mRNA for 3 beta-HSD differ during the estrous cycle, corpora lutea were collected from cycling ewes (n = 3/day) on Days 3, 6, 9, 12, and 15 postestrus. Levels of mRNA for 3 beta-HSD were similar on Days 3, 6, 9, and 12 but were lower (p < 0.05) on Day 15 postestrus, while levels of mRNA for tubulin were unchanged. In the final experiment, ewes were treated on Day 10 postestrus with two injections of PGF2 alpha (5 mg each) or saline (control) at a 4-h interval. Corpora lutea were collected from ewes (n = 4/treatment) 1 h or 8 h after the second injection of PGF2 alpha or 8 h after the second saline injection.(ABSTRACT TRUNCATED AT 250 WORDS)

More rapid restoration of pituitary content of follicle-stimulating hormone than of luteinizing hormone after depletion by oestradiol-17 beta in ewes.

To test the hypothesis that the synthesis and secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are differentially regulated after depletion by oestradiol, circulating concentrations of oestradiol were maintained at approximately 30 pg/ml for 16 days in each of 35 ovariectomized ewes. Five other ovariectomized ewes that did not receive oestradiol implants served as controls. After treatment with oestradiol, implants were removed and pituitary glands were collected from each of 5 ewes at 0, 2, 4, 8, 12, 16 and 32 days thereafter and amounts of mRNA for gonadotrophin subunits and contents of LH and FSH were quantified. Before collection of pituitary glands, blood samples were collected at 10-min intervals for 6 h. Treatment with oestradiol reduced (P less than 0.05) steady-state concentrations of LH beta- and FSH beta-subunit mRNAs and pituitary and serum concentrations of these hormones. At the end of treatment the amount of mRNA for FSH beta-subunit was reduced by 52% whereas that for LH beta-subunit was reduced by 93%. Steady-state concentrations of mRNA for FSH beta-subunit returned to control values within 2 days of removal of oestradiol, but 8 days were required for concentrations of FSH in the pituitary and serum to return to control values. Steady-state concentrations of mRNA for LH beta-subunit and mean serum concentrations of LH returned to control values by Day 8, but pituitary content of LH may require as long as 32 days to return to control levels. Therefore, replenishment of FSH beta-subunit mRNA preceded increases in pituitary and serum concentrations of FSH.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic administration of estradiol produces a triphasic effect on serum concentrations of gonadotropins and messenger ribonucleic acid for gonadotropin subunits, but not on pituitary content of gonadotropins, in ovariectomized ewes.

To determine the acute and chronic effects of estradiol on synthesis and secretion of LH and FSH, ovariectomized ewes were administered estradiol via silastic capsules for 0 h, 12 h, 1 day, 2 days, 4 days, 8 days, 16 days, or 32 days (n = 5/group). Concentrations of GnRH in the median eminence began to decrease within 12 h and were lower (p less than 0.05) than in control ewes from 1 to 4 days after estradiol administration was begun. Serum concentrations of LH were decreased relative to pretreatment control levels from 1 to 10 h, elevated during a preovulatory-like surge from 11 to 22 h, and then decreased and remained below 1 ng/ml for the duration of the experiment. Serum concentrations of FSH followed a pattern similar to those for LH except that the magnitude of change was smaller. Treatment with estradiol initially (12 h) reduced (p less than 0.05) quantities of mRNA for alpha-, LH beta-, and FSH beta-subunits, after which the quantities of mRNA for the subunits returned to near or above control levels by Day 2. After 8 days of treatment the amounts of mRNAs for gonadotropin subunits were again less (p less than 0.05) than those of controls, and they remained suppressed through Day 32. Pituitary concentrations of LH and FSH decreased (p less than 0.05) during the first day of treatment and remained suppressed for the duration of the experiment. Thus, estradiol had a triphasic effect on secretion of gonadotropins and steady-state levels of mRNA for the gonadotropin subunits, but not on pituitary content of gonadotropins.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadotropin-releasing hormone overrides the negative effect of reduced dietary energy on gonadotropin synthesis and secretion in ewes.

During prolonged periods of reduced dietary energy, there is a reduction in secretion of LH in females. To test the hypothesis that decreased secretion of LH is due to reduced secretion of GnRH, 18 ovariectomized ewes were fed either a low-energy diet (LOW, 60% of the National Research Council recommendations, n = 12) or a normal diet, (control, n = 6), for 127 days. Each ewe received basal levels (approximately 5 pg/ml) of estradiol via sc Silastic implants. After 127 days, serum concentrations of FSH and LH were reduced (P less than 0.05) by 63% and 77%, respectively in LOW ewes compared to control ewes. Pituitary concentrations of FSH and LH in LOW ewes also were reduced by 56% and 80%, respectively. Compared to levels in control ewes, concentrations of messenger RNAs for alpha-, FSH beta-, and LH beta-subunits were reduced by 75%, 76%, and 91%, respectively. Pulsatile administration of GnRH (250 ng/2 h) for three weeks to LOW ewes restored each of the parameters to levels not different from those in controls. By the end of the study, serum concentrations of GH in all LOW animals had risen dramatically, but not in control ewes. Therefore, it appears that exogenous GnRH is capable of restoring synthesis and secretion of gonadotropins in ewes receiving low-energy diets. These results provide support for the hypothesis that reduced dietary energy results in decreased secretion of GnRH.

Evidence for a direct negative effect of estradiol at the level of the pituitary gland in sheep.

The purpose of this experiment was to determine if pituitary stores of LH could be replenished by administration of GnRH when circulating concentrations of both progesterone and estradiol-17 beta (estradiol) were present at levels observed during late gestation. Ten ovariectomized (OVX) ewes were administered estradiol and progesterone via Silastic implants for 69 days. One group of 5 steroid-treated OVX ewes was given GnRH for an additional 42 days (250 ng once every 4 h). Steroid treatment alone reduced (p less than 0.01) the amount of LH in the anterior pituitary gland by 77%. Pulsatile administration of GnRH to steroid-treated ewes resulted in a further decrease (p less than 0.01) in pituitary content of LH. Compared to the OVX ewes, concentrations of mRNAs for alpha- and LH beta-subunits were depressed (p less than 0.01) in all steroid-treated ewes, whether or not they received GnRH. The ability of the dosage of GnRH used to induce release of LH was examined by collecting blood samples for analysis of LH at 15 days and 42 days after GnRH treatment was initiated. Two of 5 and 3 of 5 steroid-treated ewes that received pulses of GnRH responded with increased serum concentrations of LH after GnRH administration during the first and second bleedings, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Extreme endurance training and fiber type adaptation in rat diaphragm.

Extreme endurance training was used to investigate the adaptability of the rat diaphragm muscle fibers. During the final phase of the 14-wk training program, the animals were running for 240 min/day at an estimated requirement of 80% of pretraining maximal O2 consumption. Analysis of a sample of the costal diaphragm indicated that training resulted in a 34% reduction (P less than 0.05) in the percent distribution of type IIa fibers [27.7 +/- 1.1 vs. 18.3 +/- 2.6 (SE)] and a 15% increase (P less than 0.05) in the percent of type IIb fibers (40.0 +/- 1.2 vs. 46.1 +/- 2.4). No change (P greater than 0.05) was found in the distribution of the type I fibers (32.3 +/- 1.2 vs. 35.7 +/- 1.3). Oxidative potential as assessed with NADH-tetrazolium reductase and measured microphotometrically increased (P less than 0.05) by 19% in type I fibers but did not change in either the type IIa or type IIb fibers. No effect of training was found when a different oxidative marker, succinic dehydrogenase, was employed. Similarly glycolytic potential based on the activity of alpha-glycerophosphate dehydrogenase was not affected by training. Glycogen concentration was elevated by 60% (P less than 0.01) in type I fibers and 77% (P less than 0.01) in type IIb fibers with training but was not altered (P greater than 0.05) in type IIa fibers. Reductions (P less than 0.05) in fiber area ranging from 11 to 20% were observed in all fiber types as a result of training, whereas the number of capillaries per fiber remained static.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproducible and variable rearrangements of a Tetrahymena thermophila surface protein gene family occur during macronuclear development.

The expression of Tetrahymena surface proteins serotype H3 (SerH3) and serotype T (SerT) is under environmental regulation. SerH3 is expressed when cells are incubated between the temperatures of 20 and 35 degrees C, while SerT is expressed when cells are grown at temperatures above 35 degrees C. Using a SerH3 cDNA clone as a hybridization probe, we determined that (i) the SerH3 gene is a member of a multigene family; (ii) most members of this multigene family are variably rearranged during macronuclear development; and (iii) the gene which produces the SerH3 mRNA is reproducibly rearranged during macronuclear development.

Role of Ca2+ and Na+ on luteinizing hormone release from the calf pituitary.

It has been proposed that gonadotropin-releasing hormone (GnRH) stimulates Ca2+ entry by activation of voltage-independent, receptor-mediated Ca2+ channels in the rat gonadotroph. Little work has been done on the role of calcium in GnRH-induced luteinizing hormone (LH) release in species other than the rat. Therefore, this study was done to compare the effects of agents that alter Ca2+ or Na+ entry on LH release from calf anterior pituitary primary cells in culture. GnRH (100 ng/ml), Ca2+ ionophore A23187 (2.5 microM), and the depolarizing agent ouabain (0.1-10 microM) all produced significant increases (P less than 0.05) in LH release; these effects were significantly reduced when the cells were preincubated with the organic Ca2+ channel blockers nifedipine (1-10 microM) and verapamil (1-10 microM) and with Co2+ (0.01-1 mM). The effect of ouabain was inhibited by tetrodotoxin (TTX; 1-10 nM) as well as by nifedipine at 0.1-10 microM. In contrast to its effect on rat pituitary LH release, TTX significantly inhibited GnRH-stimulated LH release at 1-100 nM. These results suggest that GnRH-induced LH release may employ Ca2+ as a second messenger in bovine gonadotrophs and support recent speculation that GnRH-induced Ca2+ mobilization may in part be voltage dependent.

Glycogen utilization in rat respiratory muscles during intense running.

Glycogen concentration in the adult rat diaphragm and intercostal muscles has been examined following heavy treadmill exercise to determine the recruitment strategy and the significance of glycogen as a substrate to satisfy the elevated energy requirements accompanying hyperpnea. Short-term continuous running at 60 m/min and a 12 degree grade resulted in a reduction (p less than 0.05) in the concentration of glycogen (39%) in the costal region of the rat diaphragm. Similarly, glycogen concentration was significantly reduced (p less than 0.05) with this exercise protocol in all respiratory muscles studied, with the exception of the sternal region of the diaphragm. With the less intense running protocols, glycogen degradation continued to be pronounced (p less than 0.05) in the majority of the respiratory muscles sampled. The significance of muscle glycogen as a substrate for energy metabolism in the respiratory muscles was not affected by the procedure used to prepare the animal for tissue sampling (Somnitol, diethyl ether, decapitation). Examination of selected locomotor muscles revealed extensive glycogen loss in muscles composed of essentially slow oxidative fibres (soleus), fast oxidative glycolytic fibres (vastus lateralis red), and fast glycolytic fibres (vastus lateralis white). It is concluded that during heavy exercise in the rat, recruitment of motor units occurs in all regions of the diaphragm and in the intercostal muscles. At least for the costal region of the diaphragm and as evidenced by the modest (two- to four-fold) but significant (p less than 0.05) increases in lactate concentration, the increased ATP requirements in these muscles are met to a large degree by increases in aerobic metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Calmodulin antagonist effects on GnRH and secretogogue-induced release of bovine LH.

A study was performed to determine the possible role of calmodulin (CaM) in regulating gonadotropin-releasing hormone (GnRH)-induced luteinizing hormone (LH) release from the bovine pituitary using three structurally unrelated calmodulin antagonists. Primary calf anterior pituitary cell cultures (3 X 10(5)/well) were treated with either LH secretogogue (GnRH, 100 ng/ml; A23187, 2.5 microM; theophylline, 1 mM; prostaglandin E2, 1 microM; estradiol, 25 ng/ml; or KCl, 25 mM; final concentrations) or secretogogue plus CaM inhibitor in 1 ml Hanks' balanced salt solution plus 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid for 6 h. Significant (P less than 0.01) inhibition of GnRH- and A23187-stimulated LH release was obtained with calmidazolium (CMZ; 1-10 nM) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7; 1-10 microM). Both CMZ (10 nM) and W-7 (10 microM) significantly reduced (P less than 0.05) LH release by all of the other agents tested as well. In contrast, trifluoperazine (TFP; 0.1-100 microM) had no effect against most of the secretogogues tested. These results suggest that GnRH-stimulated LH release is in part a Ca2+-CaM-dependent process and may implicate a common CaM-dependent mechanism for LH release in general. The data also demonstrate a marked dichotomy in response between the phenothiazine, TFP, and other CaM antagonists in the calf pituitary.

Serotonergic and cholinergic interaction in the regulation of pituitary-adrenal function in rats.

It has been proposed that the central serotonergic inputs which modulate pituitary-adrenal secretion are mediated by cholinergic neurons. We have tested this hypothesis in intact rats. Male Sprague-Dawley rats were injected with cholinergic and serotonergic agents which enhanced transmitter function and with receptor blocking agents. Agents were injected, singly and in combination, into both unstressed and stressed animals. Since the response to cholinergic agents might be due to changes to vasopressin release, Brattleboro (vasopressin deficient) rats were also injected with cholinergic agents. The level of plasma corticosterone at 1-h post-injection was determined. Results indicate that the serotonin receptor blockade decreased the stimulatory, cholinergic effect of physostigmine. Cholinergic receptor blockers did not significantly reduce the corticosterone rise induced by 5-hydroxytryptophan. These results do not support the hypothesis of cholinergic mediation of serotonergic input. Nicotinic and muscarinic receptors appeared to exert opposing influences on the system. The nicotinic receptor antagonist was able to block the stimulatory effect of physostigmine. The muscarinic receptor antagonist significantly elevated plasma corticosterone levels. No differences were found in the effect of physostigmine on Brattleboro rats as compared to controls. These data are interpreted as suggesting that 1) the acetylcholine-induced stimulation of pituitary-adrenal function is mediated, in part, by serotonergic neurons; and 2) stimulation of nicotinic receptors is facilitatory whereas stimulation of muscarinic receptors is inhibitory to pituitary-adrenal function.

Psychoacoustic tuning curves and averaged electroencephalic responses in a patient with low-frequency sensory-neural hearing loss.

A 10-year-old girl whose bilateral, low-frequency, sensory-neural hearing loss had been noted three years earlier showed a drop in speech discrimination in her left ear with no corresponding decrease in pure-tone sensitivity. Psychoacoustic tuning curves and middle-component averaged electroencephalic responses to tone-pips suggested that damage to the left ear had become greater than indicated by the pure-tone audiogram, accounting for the drop in speech discrimination. This case suggests caution in inferring the magnitude of damage to the peripheral auditory system from tonal thresholds.