Quantitative electron-microscopic analysis of the in vivo effects of tetrahydrocannabinol on rat preovulatory follicles

The ultrastructural composition of 4 regions of rat preovulatory follicles was examined using stereological techniques following an intraperitoneal injection of tetrahydrocannabinol (THC), once each day, for 3 days prior to sacrifice on proestrus. Control rats were injected with solvent alone. Changes in nuclear, mitochondrial, lipid droplet and dense-body volume density were measured. No differences in volume density were noted in the theca or antral region of the membrana granulosa. Compared to controls, the mitochondrial volume density decreased in the peripheral region and the corona radiata. The volume density of lipid droplets decreased in the peripheral region. These changes, and their relationship to the roles of these regions in follicular steroidogenesis, are discussed.     

Capability of ovarian steroids in inducing LH surges in acutely ovariectomized rats.

The capability of estradiol (E2) or E2 and progesterone (P4) in inducing luteinizing hormone (LH) surge in acutely ovariectomized (Ovx) rats was studied. In group I, rats were Ovx on estrus and were implanted with E2 capsules and atrial cannulae immediately after operation for blood samplings. In group II, rats were also Ovx on estrus but were implanted with E2 capsules and sampling cannulae the next day (the expected diestrus day 1, D1). In group III, rats were Ovx on D1, and were implanted E2 with capsules and atrial cannulae immediately after operation. All surgical operations were done around 1000h in the morning. On the expected diestrus day 2(D2) at 0930h, one half of the rats in each group received an oil vehicle or 2mg of P4 subcutaneously. Blood samples were taken from the indwelled cannulae at 1300, 1500, and 1700hrs in the afternoon. Results showed that P4 treatment amplified LH release in all three groups of rats primed with E2, and that the oil vehicle did not assist in LH release in E2 primed rats of group I and group II, but it did in 8 out of 10 rats in group III in the late afternoon of D2. Results suggested that the estradiol alone was capable in inducing LH surge on the expected D2 afternoon, and that under estradiol-primed conditions, P4 can trigger neural initiators to advance LH surge, but that the internal hormonal milieu at the time of ovariectomy may affect the influence of ovarian steroids in inducing LH release.     

delta 9-Tetrahydrocannabinol antagonism of the anterior pituitary response to estradiol in immature female rats.

The potential estrogenicity or antiestrogenicity of delta 9-tetrahydrocannabinol (THC), the chief psychoactive constituent of marijuana, was evaluated in immature female rats treated for 3 days with estradiol (E2; 1 microgram/kg), THC (10 mg/kg body weight), or E2 + THC. Estradiol treatment significantly increased anterior pituitary, uterine, and oviduct weights. When THC was administered with E2, it prevented the E2-induced increase in pituitary weight, but had no effect on either the uterine or oviduct weight response to E2. In the E2 treatment group, basal prolactin levels were increased and a prolactin surge occurred on the afternoon of the 26th day of age. However, E2-stimulated basal and surge levels of prolactin were significantly attenuated by concomitant THC treatment. Moreover, pituitary prolactin concentrations, which were elevated in E2-treated rats, did not differ from control values in E2 + THC-treated animals. The E2-induced decrease in dopamine turnover rates in the medial basal hypothalamus and increase in the number of anterior pituitary dopamine D2-binding sites (Bmax) were not affected by concomitant THC treatment. Thus, THC antagonizes E2 action on the anterior pituitary via yet to be elucidated mechanism(s).     

Adipose differentiation-related protein: a gonadotropin- and prostaglandin-regulated protein in primate periovulatory follicles

The midcycle LH surge stimulates a rise in follicular fluid prostaglandin E2 (PGE2), which is necessary for normal ovulation. To examine PGE2-regulated processes in primate follicles, monkey granulosa cells were cultured with hCG alone or with hCG and PGE2, and the resulting total RNA was subjected to microarray analysis. Twenty PGE2-regulated mRNAs were identified, and we selected a lipid droplet protein, adipose differentiation-related protein (ADRP), for further study. To determine whether hCG and PGE2 regulate ADRP expression in vivo, monkeys received gonadotropins to stimulate multiple follicular development. Human chorionic gonadotropin was then administered alone or with the PG synthesis inhibitor celecoxib, and follicular aspirates or whole ovaries were obtained at times that span the 40-h periovulatory interval. Administration of hCG increased granulosa cell ADRP mRNA and protein, with peak levels measured just before the expected time of ovulation. Treatment with hCG and celecoxib decreased granulosa cell ADRP mRNA levels compared with those of animals treated with hCG only. ADRP was detected by immunocytochemistry in many monkey tissues that synthesize prostaglandins but was not consistently expressed by steroidogenic tissues. Granulosa cells of periovulatory follicles immunostained for ADRP after, but not before, hCG administration; ADRP colocalized with large lipid droplets within the granulosa cell cytoplasm. These studies identify ADRP as a novel gonadotropin- and PGE2-regulated protein in the granulosa cells of primate periovulatory follicles. Because ADRP facilitates arachidonic acid uptake in non-ovarian cells, ADRP-associated lipid droplets may enhance arachidonic acid uptake by granulosa cells to provide a precursor for periovulatory prostaglandin production.     

Effects of vitamin E on nicotine-induced lipid peroxidation in rat granulosa cells: Folliculogenesis

In this study, we investigated the mechanism of oxidative damage induced by nicotine and the efficacy of vitamin E, an integral component of cellular membranes, against the damage in follicular/granulosa cells of rat ovaries. The animals were randomly divided into 4 groups; control, nicotine, nicotine + vitaminE, vitamin E (n = 8, per each group). Nicotine and vitamin E were administrated intraperitoneally 1 mg/kg/day and 200 mg/kg/day, respectively, once daily for 2 weeks. Nicotine increased lipid peroxide levels such as lipid peroxide (LPO) and malondialdehyde (MDA) in serum, 4-hydroxynonenal (4-HNE) in granulosa cells and apoptotic granulosa cells in the ovary. Positive correlation occurred between the findings of LPO markers and TUNEL labeling. Level of 17-β estradiol (E₂), number of follicles and granulosa cell proliferation decreased with nicotine treatment and negatively correlated with LPO levels and apoptosis in granulosa cells. Ultrastructural study of nicotine treated rat ovaries showed mitochondrial damage and autophagosomes in the granulosa cells. The administration of nicotine and vitamin E together, revealed an increase in E₂ level, granulosa cell proliferation and the number of healthy follicles associated with decrease in LPO, MDA, 4-HNE levels and TUNEL reactivity in a manner correlated with each other, compared to the nicotine group. Vitamin E showed to alleviate mitochondrial damage and decrease the number of autophagosomes in granulosa cells. These results suggest that lipid peroxidation may be one of the nicotine’ damage mechanisms on folliculogenesis and vitamin E may prevent nicotine-induced follicular damage through reducing lipid peroxidation level in granulosa cells.     

Low‐power laser irradiation decreases lipid droplet accumulation in the parotid glands of diabetic rats

Lipid droplet accumulation has been related to salivary gland hypofunction in diabetes. In this study, the effect of laser irradiation on the parotid glands (PGs) of diabetic rats was analyzed with regard to its effect on lipid droplet accumulation, intracellular calcium concentration and calmodulin expression. The animals were distributed into 6 groups: D0, D5, D20 and C0, C5, C20, for diabetic (D) and control animals (C), respectively. Twenty‐nine days following diabetes induction, PGs of groups D5 and C5; D20 and C20 were irradiated with 5 and 20 J/cm² of a red diode laser at 100 mW, respectively. After 24 hours, PGs were removed for histological, biochemical, and western blotting analysis. The diabetic animals showed lipid droplet accumulation, which was decreased after irradiation. Ultrastructurally, the droplets were nonmembrane bound and appeared irregularly located in the cytoplasm. Moreover, diabetic animals showed an increased intracellular calcium concentration. In contrast, after laser irradiation a progressive decrease in the concentration of this ion was observed, which would be in agreement with the results found in the increased expression of calmodulin in D20. These data are promising for using laser to decrease lipid droplet accumulation in PGs, however, more studies are necessary to better understand its mechanisms. Micrographs showing decreased lipid accumulation after laser irradiation in light micrographs (LM), and morphology of lipid droplet in transmission electron microscopic (TEM). LM: (A) PGs from nondiabetic rats that did not receive Laser irradiation (LI), (B) PGs from nondiabetic rats that received a dose of 20 J/cm², (C) lipid accumulation (arrows) in the secretory cells from diabetic rats that did not receive irradiation, (D) reduction of lipid accumulation in the secretory cells from diabetic rats that received a dose of 20 J/cm² and TEM: (E) scale bar = 5 μm, (F) scale bar = 1 μm, and (G) scale bar = 0.5 μm.      

Effects of anandamide on gestation in pregnant rats

The present study was to test whether the recently described endogenous ligand for the cannabinoid receptor; arachidonyl-ethanolamide (anandamide, ANA), may produce similar effects on pregnancy as the main psychoactive component of marihuana: Δ⁹-tetrahydrocannabinol (THC) in rats. ANA, THC (0.02 mg/kg i.p./day, respectively) or vehicle were injected daily over the third week of pregnancy. The pregnant rats were either killed on day 21 of pregnancy or followed up to delivery. Results show a significant increase in the duration of pregnancy after both THC and ANA treatment. Both drugs caused an increase in the frequency of stillbirths. The mothers' hormone contents in tissues and sera were measured. Decreased LH content was observed in the serum of treated animals. No changes in FSH content were observed either in the pituitary or in the sera. Pituitary prolactin (PRL) levels was lower in ANA treated animals as compared both to controls or THC treated subjects. The serum PRL content decreased in all experimental groups. Decrease in serum progesterone was more prominent in treated rats. Serum levels of prostaglandins (PGF 1 and PGF 2) were significantly decreased after THC and ANA treatment. We conclude that ANA has the same tendency to change reproductory parameters in pregnant rats as THC, although in some cases the effects of ANA were slightly different from that of THC. Both endogenous and exogenous cannabinoids inhibit PG synthesis in pregnant rats and this maybe responsible for the delay constitute the mechanism in the onset of labour.     

A quantitative electron microscopic analysis of the membrana granulosa of rat preovulatory follicles

The ultrastructure of the membrana granulosa (MG) of rat preovulatory follicles was examined using stereological techniques. Organelles studied were nuclei, mitochondria, lipid droplets (LD), lysosomes, and smooth and rough endoplasmic reticulum (SER, RER). The peripheral region of the MG contained the greatest volume of mitochondria, LD and SER, organelles associated with steroidogenesis. The volume of RER, an organelle associated with protein production, was greatest in the cumulus oophorus. These results corroborate previous analyses and demonstrate that the rat MG is composed of discrete subregions.     

Splenic macrophages enhance prolactin-induced progestin secretion from mature rat granulosa cells in vitro.

The effect of splenic macrophages on in vitro progestin secretion (the sum of the progesterone and 4-pregnen-20 alpha-ol-3-one concentrations in the medium) from mature rat granulosa cells was examined by means of co-culture techniques. When splenic macrophages (3.0 x 10(5) cells/ml) obtained from adult female rats on the evening of proestrus (1800 h) were added to granulosa cells (1.5 x 10(5) cells/ml) and co-cultured for 96 h in the absence of prolactin (PRL), progestin secretion from granulosa cells did not change. However, co-culture of granulosa cells with the macrophages in the presence of PRL (2 micrograms/ml) significantly enhanced progestin secretion after 48 h of culture. This stimulatory effect on progestin secretion was observed only when the number of macrophages added was more than twice the number of granulosa cells. On the other hand, splenic macrophages obtained on the evening of diestrus had no effect on progestin secretion from granulosa cells even in the presence of PRL. These results suggest that splenic macrophages can enhance PRL action so as to stimulate progestin secretion from granulosa cells and that this function of splenic macrophages varies during the estrous cycle.     

Antioxidant effect of tetrahydrocurcumin in streptozotocin-nicotinamide induced diabetic rats

Oxidative stress has been suggested to be a contributory factor in development and complication of diabetes. In the present study, we have investigated the effect of tetrahydrocurcumin (THC), one of the active metabolites of curcumin on antioxidants status in streptozotocin-nicotinamide induced diabetic rats. Oral administration of THC at 80 mg/kg body weight of diabetic rats for 45 days resulted in significant reduction in blood glucose and significant increase in plasma insulin levels. In addition, THC caused significant increase in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, reduced glutathione, vitamin C and vitamin E in liver and kidney of diabetic rats with significant decrease in thiobarbituric acid reactive substances (TBARS) and hydroperoxides formation in liver and kidney, suggesting its role in protection against lipid peroxidation induced membrane damage. These biochemical observations were supplemented by histopathological examination of liver and kidney section. The antidiabetic and antioxidant effects of THC are more potent than those of curcumin at the same dose. Results of the present study indicated that THC showed antioxidant effect in addition to its antidiabetic effect in type 2 diabetic rats.     

Modifications des cellules gonadotropes de la préhypophyse chez la ratte injectée de testostérone au cours du cycle oestral

Summary 4-day cyclic adult female Wistar rats were injected subcutaneously with testosterone propionate on diestrus 1 at 16:00 and on diestrus 2 at 10:00 respectively. Non-injected females served as controls. Autopsy was performed on diestrus 2 at 23:00, and on proestrus at 14:00 and 17:00 respectively. The blue Alcian-PAS staining was used to evidence FSH () and LH () pituitary cells.In control animals and in diestrus 2 injected females only a small number of FSH cells could be detected on diestrus 2 at 23:00. This number increased markedly on proestrus at 14:00 and decreased on proestrus at 17:00. A similar evolution was observed in diestrus 1 testosterone injected females, but the number of FSH cells appeared higher at any stage of autopsy in these females than in diestrus 2 injected females and in control rats.In control females, numerous LH cells were observed on diestrus 2 at 23:00. The number of these cells was diminished on proestrus at 14:00 and still more at 17:00. On the contrary few LH cells were detected in testosterone injected females on the evening of diestrus 2. An increase of these cells occurred on proestrus at 14:00, followed at 17:00 by only a weak diminution as established by comparison with control animals.An inhibition of FSH release and a suppression of the proestrus surge of LH were therefore supposed to cause, on one hand, the slowing up of follicular growth observed in diestrus 1 injected females and, on the other hand, the blockage of ovulation noted in both diestrus 1 and diestrus 2 treated animals.

Travail effectué avec l'aide de la D.G.R.S.T. Contrat n^o 72.7.0030.     

Vitamin D and phosphate regulate fibroblast growth factor-23 in K-562 cells

Female rats were treated with FSH (40 IU/kg) on the first and second diestrus days (D1 and D2) and with LH (40 IU/kg) on the proestrus (P) day to synchronize and maximize ovarian changes. Follicle area increased by 50% from D1 to P, and the estrus (E) phase showed multiple corpora lutea and massive apoptosis. Increased oxygen uptakes (42-102%) were determined in ovary slices and in isolated mitochondria in active state 3 along the proliferation phase (D1-D2-P) that returned to initial values in the E phase. Mitochondrial content and the electron transfer activities of complexes I and IV were also maximal in the P phase (20-79% higher than in D1). Production of NO by mitochondrial nitric oxide synthase (mtNOS), biochemically determined, and the mtNOS functional activity in regulating state 3 oxygen uptake were also maximal at P and 79-88% higher than at D1. The moderately increased rate of NO in the proliferative phase is associated with mitochondrial biogenesis, whereas the high rate of NO generation by mtNOS at phase P appears to trigger mitochondria-dependent apoptosis. The calculated fraction of ovary mitochondria in state 3 was at a minimal value at the P phase. Mitochondrial oxidative damage, with increased thiobarbituric acid-reactive substances and protein carbonyls, indicates progressive mitochondrial dysfunction between phases P and E. The roles of mitochondria as ATP provider, as a source of NO to signal for mitochondrial proliferation and mitochondria-dependent apoptosis, and as a source of O(2)(-) and H(2)O(2) appear well adapted to serve the proliferation-apoptosis sequence of the ovarian cycle.     

Effects of Phytoestrogen on Mitochondrial Structure and Function of Hippocampal CA1 Region of Ovariectomized Rats

The present study was undertaken to evaluate whether estrogen deprivation might lead to mitochondrial alteration of hippocampal neurons of ovariectomized (OVX) rats, and to evaluate the protective effect of estrogen and phytoestrogen on the mitochondrial alteration. First, OVX rats were used to mimic the pathologic changes of neurodegeneration of postmenopausal female, and we looked into the alteration of the mitochondrial ultrastructure and ATP content of hippocampal CA1 region after ovariectomy on different phase by transmission electron microscope (TEM) and reversed-phase high-performance liquid chromatography (HPLC), and found the best phase points of the alteration of the mitochondrial ultrastructure and ATP content. Next, estrogen and phytoestrogen were administered to the OVX rats for the protective effects on the mitochondrial ultrastructure and ATP content. Meanwhile, the density, size, shape, and distribution parameters of mitochondrial ultrastructure were analyzed according to the morphometry principle. The experimental results presented that (1) The alteration of mitochondrial ultrastructure elicited by ovariectomy worsened with the days going on, and the changes were the most noteworthy in volume density (Vv), average surface area (S), specific surface area (δ), and particle dispersity (Cλz) on 12th day (P < 0.05 or P < 0.01). Moreover, there was no statistical significance of the numerical density (Nv) among the five groups in the first step experiment. (2) The treatment with estrogen, genistein (Gs), and ipriflavone (Ip) significantly reversed the effect elicited by ovariectomy on Vv, S, δ, Cλz, Nv, and particle average diameter (D) of mitochondria of hippocampal CA1 region (P < 0.05). (3) Furthermore, ATP content of hippocampal CA1 region after ovariectomy declined significantly on 7th day (P < 0.05), and estrogen and phytoestrogen could reverse the alteration (P < 0.05). Taken together, these results revealed that phytoestrogen may have a protective role against the neurodegeneration after menopause via protecting mitochondrial structure and functions. Phytoestrogen may be a good alternative as a novel therapeutic strategy for menopausal syndrome.     

Antihyperlipidemic effect of chlorogenic acid and tetrahydrocurcumin in rats subjected to diabetogenic agents

Diabetes mellitus is associated with dyslipidemia, which is a significant risk factor for cardiovascular complications. The present study was carried out to evaluate the effects of tetrahydrocurcumin (THC) and chlorogenic acid (CGA) alone and in combination on alterations in lipids, lipoproteins and enzymes involved in lipid metabolism in streptozotocin (STZ)–nicotinamide (NA)-induced type 2 diabetic rats. A significant (p < 0.05) increase in the concentrations of plasma and tissue (liver and kidney) lipids (cholesterol, triglycerides (TGs), free fatty acids (FFAs) and phospholipids (PLs)) and low density and very low-density lipoproteins (LDL and VLDL), and a decrease in the concentration of high-density lipoproteins (HDL) were noticed in STZ administered diabetic rats. In addition, the activity of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase increased significantly (p < 0.05) in the liver and kidney whereas the activities of lipoprotein lipase (LPL) and lecithin cholesterol acyl transferase (LCAT) were decreased significantly (p < 0.05) in the plasma of diabetic rats. Combined administration of CGA (5 mg/kg b.w.) and THC (80 mg/kg b.w.) for 45 days remarkably reduced the STZ-induced changes in lipids, lipoproteins and lipid metabolising enzymes when compared to the effects of CGA or THC alone in diabetic rats. These results indicate that combination of THC and CGA can potentially ameliorate lipid abnormalities in experimental type 2 diabetes.     

Prostaglandin E(1) inhibits abnormal follicle rupture and restores ovulation in indomethacin-treated rats

In the presence of indomethacin, an inhibitor of prostaglandin (PG) synthesis, the gonadotropin surge induces abnormal follicle rupture at the basolateral follicle sides, thus preventing effective ovulation in rats. This study was undertaken to analyze whether exogenous prostaglandin administration can overcome the antiovulatory action of indomethacin. Cycling rats were treated with vehicle (olive oil) or indomethacin (1 mg/rat) on the morning of proestrus. Rats treated with indomethacin were injected with different doses (50, 250, or 500 micro g/rat) of PGE(1), PGE(2), PGF(2alpha), or vehicle (saline) at 1900 h in proestrus. The ovulatory response was analyzed on the morning of estrus by evaluating follicle rupture and the location of the oocytes in serially sectioned ovaries. The number of oocytes in the oviducts was also counted in rats treated with the highest prostaglandin doses. In indomethacin-treated rats, most newly formed corpora lutea showed abnormal follicle rupture at the basolateral sides. In addition, invasion of the ovarian stroma and blood and lymphatic vessels by granulosa cells and follicular fluid was observed. Prostaglandins of the E series, and especially PGE(1), inhibited abnormal follicle rupture and restored ovulation, although the number of oocytes in the oviducts were significantly decreased. PGF(2alpha) was only partially effective in inhibiting abnormal follicle rupture and restoring ovulation. These data suggest that prostaglandins of the E series, and particularly PGE(1), play a crucial role in ovulation by determining the targeting of follicle rupture at the apex, thus allowing release of oocytes to the periovarian space.     

Muscle mitochondrial ultrastructure in exercise-trained iron-deficient rats

To investigate effects of endurance training and iron deficiency, as well as the combination of these two conditions, on mitochondrial ultrastructure, weanling rats at 3 wk of age were assigned to iron-deficient (Fe-) and iron-sufficient (Fe+) groups. Subsequently, groups were subdivided into exercise-trained (T) and sedentary (S) groups. Electron microscopy showed subsarcolemmal and intrafibrillar mitochondria in the Fe-T animals to be enlarged with sparse cristae and vacuole-like areas compared with the other groups. An increase in the number of lipid droplets in both Fe- groups was observed. Stereological measurements revealed a 99% increase in the volume occupied by muscle mitochondria in the Fe-T animals (11.9 +/- 0.8%) over the Fe+T (5.9 +/- 0.4%) and Fe+S (6.0 +/- 0.3%) groups and a 55% increase over the Fe-S groups (7.7 +/- 0.3%). The ratio of mitochondrial surface area to tissue volume was significantly decreased only in the Fe-T group. These results indicate that the combined stresses of iron deficiency and training produce mitochondrial ultrastructural changes far greater than those of iron deficiency or training alone. Because this is also the case with the disproportion among mitochondrial enzymes, it is possible that the ultrastructural changes are indicative of morphological responses that maintain ATP turnover during exercise in iron deficiency when oxygen transport and electron transport chain activities are reduced.     

Modulation of MLC-2v gene expression by AP-1: Complex regulatory role of Jun in cardiac myocytes

Walker 256 tumour-bearing rats were fed pelleted chow containing low-gamma-linolenic acid (GLA) (2.98%) or high-GLA (5.55%) during the twelve-day period after subcutaneous implantation of the tumour. The presence of n-6, polyunsaturated GLA in the diet caused a concentration-dependent decrease in tumour growth, reaching an almost 50% reduction in final tumour weight in the high-GLA group. The eicosatrienoic acid content of the whole tumour homogenate and of the Percoll-purified mitochondrial fraction was increased by the GLA-rich diets. Changes in the fatty acid composition of the cytoplasmic acyl CoA pool were also found, with increases in GLA content in both the low- and high-GLA groups. Additionally, increases in eicosatrienoic acid and arachidonic acid were found in the high-GLA group. Both the cytoplasmic acyl CoA content and the mitochondrial acyl CoA synthetase activity were increased by GLA in the diet and lipid peroxidation was also increased as determined by an increase in TBARS content. Changes in mitochondrial fatty acid composition were accompanied by a decrease in the mitochondrial membrane potential in the high-GLA group. Tumours from the control and GLA groups were examined by transmission electron microscopy. This revealed an increase in mitochondrial area and volume in the high-GLA group, in comparison with the control group, as well as a change in general cell ultrastructure, with many cells found in an apoptotic state or in a necrotic state, possibly secondary to apoptosis. The data presented show that the addition of GLA to the diet of Walker 256 tumour-bearing rats can greatly decrease the rate of development of the tumour burden. This may be, in part, due to the accumulation of poorly metabolised acyl CoA's within the tumour cell cytoplasm which, when coupled with altered mitochondrial composition, membrane potential and ultrastructure, may be a signal for cell death.     

Quantitative Ultrastructural Investigations of Mitochondrial Development in Leishmania donovani During Transformation*

SYNOPSIS. The ultrastructure of the mitochondrion during transformation of Leishmania donovani from amastigote to promastigote stages was studied by morphometric analysis. There was a slight but significant decrease in relative mitochondrial volume (Vvli) during transformation. This decrease was linear with time for at least 27 hr. No change in relative lipid inclusion volume (Vvli) was observed during transformation. The ratio of inner to outer mitochondrial surface membrane densities (Svmii:Svmio) also remained unchanged. Although the relative number of cristae remains unchanged after transformation, there is an increase in cristae number in the portion of the kinetoplast opposite the flagellum.     

Effect of alterations in pulsatile luteinizing hormone release on ovarian follicular atresia and steroid secretion on diestrus 1 in the rat estrous cycle

This study examined the importance of pulsatile luteinizing hormone (LH) release on diestrus 1 (D1; metestrus) in the rat estrous cycle to ovarian follicular development and estradiol (E2) secretion. Single injections of a luteinizing hormone-releasing hormone (LHRH) antagonist given at -7.5 h prior to the onset of a 3-h blood sampling period on D1 reduced mean blood LH levels by decreasing LH pulse amplitude, while frequency was not altered. Sequential injections at -7.5 and -3.5 h completely eliminated pulsatile LH secretion. Neither treatment altered the total number of follicles/ovary greater than 150 mu in diameter, the number of follicles in any size group between 150 and 551 mu, or plasma E2, progesterone, or follicle-stimulating hormone (FSH) levels. However, both treatments with LHRH antagonist significantly increased the percentage of atretic follicles in the ovary. These data indicate that: 1) pulsatile LH release is an important factor in determining the rate at which follicles undergo atresia on D1; 2) reductions in LH pulse amplitude alone are sufficient to increase the rate of follicular atresia on D1; 3) an absence of pulsatile LH release for a period of up to 10 h on D1 is not sufficient to produce a decline in ovarian E2 secretion, most likely because the atretic process was in its early stages and had not yet affected a sufficient number of E2-secreting granulosa cells to reduce the follicle's capacity to secrete E2; and 4) suppression or elimination of pulsatile LH release on D1 is not associated with diminished FSH secretion.     

Effects of estradiol benzoate and progesterone on superoxide dismutase activity in the thymus of rats

The activity of mitochondrial superoxide dismutase (MnSOD) and cytosol superoxide dismutase (CuZnSOD) was measured in corresponding subcellular fractions prepared from the thymi of intact and chronically gonadectomized (GX) rats of both sexes, as well as of GX male and female rats injected subcutaneously with a single dose of 5 microg estradiol benzoate (EB) and/or 2 mg progesterone (P). Animals were sacrificed 2 h or 24 h following hormone treatment. In the females, the activity of MnSOD in the thymus was stable during the estrous cycle and did not change after ovariectomy. Treatment of GX females with estradiol benzoate resulted 2 h later in a significant elevation of MnSOD activity, whereas 24 h later the activity returned back to control values. On the other hand, treatment of GX females with progesterone had no effect on the MnSOD activity. However, combined hormone treatment, in which EB injection preceded progesterone injection by one hour, enhanced the effect on MnSOD activity similar to that of estradiol benzoate alone. The activity of CuZnSOD in cycling rats was increased in proestrus, whereas removal of the ovaries kept the values at low diestrus and estrus levels. Contrary to MnSOD, CuZnSOD activity did not change after EB treatment of GX females, while progesterone increased the enzyme activity at 2 h and 24 h after hormone treatment. However, combined EB+P treatment proved to be ineffective. In the males, neither MnSOD nor CuZnSOD activity was affected by the removal of testes or by progesterone treatment of GX animals. Only EB injection to GX rats significantly increased CuZnSOD activity 24 h later.