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V K Ganjam

Publications and source records attributed to V K Ganjam.

At least 55 records · Page 3Linked to original sources
PubMed1991

Hormonal control of Leydig cell differentiation.

Leydig cell progenitors contain significant concentrations of androgen receptors. When the metabolism of DHT to 3 alpha-DIOL is blocked, DHT stimulates testosterone production by Leydig cell progenitors, most probably via an androgen receptor dependent mechanism. Rapid metabolism by 3 alpha-HSD may limit the potency of exogenous DHT to stimulate differentiation of Leydig cell progenitors in vitro. Insulin-like growth factor-I enhances androgen production by purified immature Leydig cells. The elevated sensitivity of immature Leydig cells versus adult Leydig cells to IGF-I stimulation indicates that this peptide hormone has a role in their differentiation during puberty.

Androgens↗
PubMed1990

Effects of fetal alcohol exposure on brain 5 alpha-reductase/aromatase activity.

The local formation of the testosterone metabolites 5 alpha-dihydrotestosterone and 17 beta-estradiol within the hypothalamic-preoptic area (HPOA) is essential for the normal sexual differentiation of the male central nervous system (CNS) during a perinatal critical period in the rat. Testosterone, the substrate for these reactions, is derived primarily from synthesis within the fetal testis. Fetal alcohol exposure (FAE) during this critical period profoundly affects fetal testicular steroidogenesis as well as the sexual differentiation of the CNS. The present study was conducted to determine whether FAE directly affects the local metabolism of androgens within the developing CNS or whether reduced androgen substrate, via a testicular lesion, is a more likely explanation for the known effects of FAE on the CNS. The enzymatic activities of 5 alpha-reductase and aromatase were simultaneously quantitated in the newborn rat HPOA following FAE. Neither the enzymatic activity of 5 alpha-reductase, aromatase nor their ratio were significantly influenced (P greater than 0.05) by FAE with respect to controls. FAE apparently does not alter the disposition of the androgens within the newborn rat HPOA. These results support the hypothesis that FAE alters the sexual differentiation of the CNS through inhibition of androgen biosynthesis at the level of the perinatal rat testis.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1990

Influence of rete testis fluid deprivation on the kinetic parameters of goat epididymal 5 alpha-reductase.

A surgical technique to cannulate the rete testis of the goat was utilized to examine the effects of rete testis fluid (RTF) deprivation on the enzymatic activity of epididymal 5 alpha-reductase. Kinetic techniques were used to determine whether the regional enzymatic effect of RTF deprivation is to decrease the apparent number of 5 alpha-reductase active sites or the catalytic activity of each active site within the epididymal epithelium. Paired comparisons of (Vmax)app and (Km)app values between control and RTF-deprived epididymides indicated that RTF deprivation affected the value of (Vmax)app with no apparent change in the values of (Km)app in caput, corpus, and cauda epididymal regions. We conclude that RTF deprivation in the goat epididymis for 7 days results in a decreased number of apparent 5 alpha-reductase active sites within the epididymal epithelium.

Animals↗
PubMed1990

Gonadotoxic effects of 2-hexanone and 1,2-dibromo-3-chloropropane on the enzymatic activity of rat testicular 17 alpha-hydroxylase/C17,20-lyase.

In this study the gonadotoxic effects of 2-hexanone administered as a pretreatment and/or 1,2-dibromo-3-chloropropane administered as a challenge on the activity of several key steroidogenic enzymes in the rat testis were examined. Despite the absence of an effect when either treatment was administered individually, the pretreatment/challenge combination inhibited the steroidogenic capacity of the rat testis. The specific activity of testicular 17 alpha-hydroxylase was significantly reduced (P less than 0.05), with respect to the control, following the pretreatment/challenge combination. There were no significant differences between the control and the individual treatments. The inhibition of 17 alpha-hydroxylase activity occurred in the absence of significant differences in testis weight and testicular protein content. This inhibition of testicular steroidogenic enzyme activity was specific as the activity of another testicular enzyme, namely C17,20-lyase, was not affected by any treatment. The decline in rat testicular 17 alpha-hydroxylase activity 18 h after the 1,2-dibromo-3-chloropropane challenge precedes the reported alterations in the seminiferous epithelium following this same treatment. The results of the present study indicate that the steroidogenic cell of the testis, i.e. the Leydig cell, is a potential site for the primary toxic effects of these agents in the rat testis.

Animals↗
PubMed1990

Intrauterine position effects in male and female swine: subsequent survivability, growth rate, morphology and semen characteristics.

Pigs of known intrauterine position were obtained from 31 litters by a procedure in which donor sows were slaughtered at d 112 of gestation, their uteri removed and piglets delivered manually. Uterine position was recorded for each piglet as being positioned between two female fetuses (OM), between a male and female fetus (1M), between two male fetuses (2M), between a female fetus and the tip of the uterine horn (OE) or between a male fetus and the tip of the horn (1E). Piglets were fostered as litter groups to recipient sows and reared in these groups until 120 d of age. They then were regrouped and housed as groups of three and six for males and females, respectively. Intrauterine position had no effect on birth weight or survivability of pigs of either sex, although pigs positioned in utero nearest the ovaries (OE and 1E) tended to be heavier at birth. Body weights were similar among groups in each sex at 120 and 175 d of age when given ad libitum access to feed; however, 2M males gained more weight from d 175 to 270 under restricted feeding conditions (P less than .05). Intrauterine position had no effect on anogenital distances either at birth or 120 d of age, and predicted testes weights were similar among males from different positions. Semen characteristics at 220 d of age did not appear to vary due to prenatal environment. Although volume tended to be less for 0M males (P less than .12), concentration, motility and sperm/ejaculate were similar among groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Prenatal ethanol exposure alters steroidogenic enzyme activity in newborn rat testes.

We have examined the in utero effects of ethanol exposure on testicular steroidogenesis in newborn male pups. Pregnant Sprague-Dawley rats were fed a liquid ethanol diet (35% ethanol-derived calories), a pair-fed isocaloric liquid diet, or a standard laboratory rat chow and water diet beginning on Day 12 of gestation and continuing through parturition. Although there were no significant differences in the enzymatic activity of 5-ene-3 beta-hydroxysteroid dehydrogenase/isomerase or C17,20-lyase, the enzymatic activity of 17 alpha-hydroxylase was significantly (p less than 0.01) reduced (i.e., approximately 36%) in the ethanol-exposed pups compared to those from the pair-fed and chow treatment groups. This lesion in testicular steroidogenic enzyme activity in newborn male pups exposed to alcohol in utero was transient as 17 alpha-hydroxylase activity from the ethanol-exposed animals returned to control levels by postnatal Day 20 and remained at control levels through adulthood (postnatal Day 60). These data suggest that the suppression of the perinatal testosterone surge in male rats exposed to alcohol in utero and the associated long term demasculinizing effects of prenatal ethanol exposure might be the result of reduced testicular steroidogenic enzyme activity in the perinatal animal.

3-Hydroxysteroid Dehydrogenases↗
PubMed1988

Radiometric quantitation of delta 4-3-ketosteroid-5 alpha-oxidoreductase utilizing high performance liquid chromatography.

A reliable isocratic high performance liquid chromatography (HPLC) procedure has been developed for the separation and subsequent radiometric quantitation of delta 4-3-ketosteroid-5 alpha-oxidoreductase enzyme activity. The specificity of this HPLC procedure has been confirmed through the use of authentic androgen radioisotopes, linearity of detector response, and mass spectral analysis. In conjunction with this we have also developed a simple Sep-Pak sample preparation procedure which allows the uniform complete isolation of these androgens from epididymal tissue homogenates. Utilizing these procedures we have determined the regional distribution of 5 alpha - reductase in the epididymis of the CD-1 mouse. Regional differences in enzyme activity were found between the caput-corpus and cauda regions. Enzyme activity (specific activity) was higher in the caput-corpus region (28.98 pmol 5 alpha - reduced androgens formed/h/mg protein) than the cauda region (6.20 pmol 5 alpha - reduced androgens formed/h/mg protein).

Androstane-3,17-diol↗
PubMed1988

Effect of feeding on renin-angiotensin-aldosterone system of the horse.

The effect of feeding frequency and associated meal size on the renin-angiotensin-aldosterone system (RAAS) in seven horses was examined. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen (MF), in which the ration was divided into six equal portions fed at 4-h intervals, or as a single large feeding (SF) given from 9 A.M. until 11 A.M. Plasma renin activity (PRA), aldosterone (PAC), cortisol (PCC), protein concentration (TP), packed cell volume (PCV), and serum sodium and potassium were measured serially. To prevent significant RAAS stimulation due to strenuous exercise or by assuming orthostatism after a period of recumbency, the horses were trained to stand in 1 X 4-m tie stalls during the experiments. Changes in Na intake were prevented by disallowing nonration salt sources. A 12:12 light-dark interval was maintained. During the MF experiment, only serum Na changed diurnally, with concentrations lowest in early morning and highest before midday. In contrast, during the SF experiment, PRA was increased at 0.5, 1.0, and 3.0 h and PAC was increased at 3.0, 5.0, and 7.0 h after onset of feeding (P less than 0.005). Increased TP and PCV suggested transient hypovolemia was responsible for renin release. Significant increases in Na and decreases in K occurred while eating; however, K increased postprandially to be coincident with aldosterone. Except for a transient increase during feeding in SF, PCC demonstrated a similar circadian rhythm in both experiments. It was concluded that 1) episodic feeding (SF) causes significant diurnal variation of the RAAS in the horse, and 2) spontaneous circadian activity of the RAAS cannot be demonstrated in this species during a steady-state feeding regimen (MF).

Aldosterone↗
PubMed1987

The effects of stanozolol and boldenone undecylenate on plasma testosterone and gonadotropins and on testis histology in pony stallions.

Fifty 2- to 16- yr old pony stallions were randomly assigned to one of five treatments: Group 1, controls (no treatment); Group 2, 0.55 mg/kg stanozolol weekly for 13 treatments; Group 3, 1.1 mg/kg stanozolol every 3 wk for 5 treatments; Group 4, 1.1 mg/kg boldenone undecylenate every 3 wk for 5 treatments; and Group 5, 0.55 boldenone undecylenate weekly for 13 treatments. Mean plasma testosterone levels for Groups 2, 4, and 5 were elevated over controls (P<0.01) at 2, 8, and 9 wk, respectively. Testosterone levels for ponies in Group 3 did not differ from controls (P>0.05). There were no differences in mean plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels among groups (P>0.05). Daily spermatid production per gram of testicular parenchyma (DSP/gm) in Group 5 was lower than in controls (P<0.05), whereas DSP/gm was not different among groups 1 to 4 (P>0.05). There were no differences among groups (P>0.05) in the percentage of Stage 8 tubules or relative number of Leydig cells. The mean diameter of Leydig cells was less for Group 5 than for controls (P<0.05), but was not different for Groups 1 to 3 (P>0.05).

Journal Article↗
PubMed1987

Unique regional distribution of delta 4-3-ketosteroid-5 alpha-oxidoreductase and associated epididymal morphology in the marsupial, Didelphis virginiana.

The epididymal epithelial ultrastructure has been described in the adult male North American opossum, Didelphis virginiana. Morphological results have suggested that absorptive activity is prominent in the proximal epididymal region by virtue of numerous microvilli, an endocytotic complex, dense granules, and multivesicular bodies in the apical cytoplasm. In contrast, the middle and distal epididymal regions exhibit ultrastructural features indicative of protein synthesis such as large invaginated euchromatic nuclei, large nucleoli, and increased amounts of granular endoplasmic reticulum. It is in the middle and distal epididymal regions where sperm head rotation and sperm pairing take place. Epididymal delta 4-3-ketosteroid-5 alpha-oxidoreductase (5 alpha-reductase) activity also has been measured. It has been found that the level of enzyme activity differs significantly (p less than 0.01) between the proximal, middle, and distal epididymal regions. Enzyme-specific activity has been found to be highest in the middle region (47.6 +/- 5.4 picomoles 5 alpha-reduced androgens formed/b/mg protein), lower in the distal region (18.3 +/- 0.7 picomoles 5 alpha-reduced androgens formed/b/mg protein), with little activity (2.4 +/- 1.2 picomoles 5 alpha-reduced androgens formed/h/mg protein) found in the proximal epididymal region. This regional distribution of enzyme activity differs markedly from that reported for eutherian mammals. Both the suggested epididymal protein synthetic and secretory activity and the level of epididymal 5 alpha-reductase activity appear to correlate regionally with the morphological changes that occur in the opossum spermatozoa as they transit the epididymis.

Animals↗
PubMed1987

Distribution and implications of beta-endorphin and ACTH-immunoreactive cells in the intermediate lobe of the hypophysis in healthy equids.

The distribution of cells that stain positive for beta-endorphin and ACTH immunoreactivity was studied in the pars intermedia (PI) of the hypophysis in 3 healthy horses and 2 healthy ponies. Serial sections treated with commercial antibodies generated against beta-endorphin or ACTH were processed for immunocytochemical studies, using the avidin biotin immunoperoxidase-complex method. Distribution patterns of cells reacting with antibodies were similar in cells from all equids. Cells immunostained for ACTH were numerous and widely distributed in the PI. Cells immunopositive for ACTH probably contain corticotrophin-like intermediate lobe peptide that cross-reacts with antisera to ACTH. Cells immunopositive for beta-endorphin were fewer in number and had a more limited distribution in the PI. Most beta-endorphin-positive cells were located along the border of the PI adjacent to the lobus nervosus and had abundant eosinophilic cytoplasm when stained with hematoxylin and eosin. Cells with prominent eosinophilic cytoplasm were not common in other areas of the PI. When serial sections were examined, cells that stained positive for beta-endorphin immunoreactivity also appeared positive for ACTH.

Adrenocorticotropic Hormone↗
PubMed1984

Surgical technique to cannulate the rete testis of the goat.

A surgical technique was devised to collect rete testis fluid from 14 mature goats. The tubular portion of the extratesticular rete testis was cannulated where it penetrated the tunica albuginea of the testis under the center of the head of the epididymis. The tip of the cannula was sutured in place in the extratesticular rete testis and the opposite end was passed through the scrotum and into a plastic collection bottle. The bottle was glued to pillow ticking, which was sutured to the scrotum. Continuous flow of rete testis fluid occurred for 0 to 14 days and was usually terminated by a sperm clot in the cannula. The flow rate was 0.59 +/- 0.37 ml/hr.

Animals↗
PubMed1983

Plasma and endometrial progesterone content following exogenous progesterone administration in mares.

Intact and ovariectomized pony mares were treated with either progesterone in-oil or repositol progesterone. Serum progesterone, endometrial progesterone and endometrial histology were examined. There were no differences in serum or tissue progesterone between intact and ovariectomized mares. Serum and tissue progesterone were greater for progesterone in-oil treated mares than for repositol treated mares. Both progesterone in-oil and repositol progesterone initiated endometrial gland proliferation with no difference in response observed between the two preparations.

Journal Article↗
PubMed1983

The effects of stanozolol and boldenone undecylenate on scrotal width, testis weight, and sperm production in pony stallions.

Fifty mature pony stallions were randomly assigned to one of five treatment groups: Group 1- controls (no treatment), Group 2 - 0.55 mg/kg stanozolol weekly for 13 treatments, Group 3 - 1.1 mg/kg stanozolol every 3 weeks for 5 treatments, Group 4 - 1.1 mg/kg boldenone undecylenate every 3 weeks for 5 treatments, and Group 5 - 0.55 mg/kg boldenone undecylenate weekly for 13 treatments. Scrotal widths (SW), combined testis weights (CTW), and daily sperm productions (DSP) were not different between Groups 1 and 2. Ponies in Group 5 had smaller SW (P<0.01), smaller CTW and decreased DSP compared to controls (P < 0.05). Although SW for ponies in Groups 3 and 4 were less than for controls (P < 0.01), CTW and DSP were not different. The only treatment regime that did not alter SW, CTW, and DSP was Group 2 (0.55 mg/kg stanozolol weekly for 13 treatments).

Journal Article↗
PubMed1983

Effect of deprival of rete testis fluid on the morphology of efferent ductules.

One week after unilateral cannulation of the rete testis and ligation of the efferent ductules, samples of the proximal, middle and distal segments of the efferent ductules of 6 goats were examined by light and electron microscopy and compared with normal contralateral efferent ductules. The pseudostratified columnar epithelium consisted of ciliated, nonciliated and basal cells. The number of clear vacuoles decreased markedly in the proximal and middle segments following deprivation of androgen-rich rete testis fluid. The epithelium of the distal segment of the cannulated side had few large clear vacuoles compared to the normal side, which had a high concentration of large vacuoles. Since the large vacuoles decreased in all three segments following ligation, they were thought to be absorptive. Some cells of the distal segment of the cannulated side contained a single, huge, basal vacuole. Electron-dense, membrane-bound granules were abundant in the proximal segment of normal ductules. After cannulation these granules were still present. It was concluded that the electron-dense granules were insensitive to rete testis fluid and that they did not arise from the fluid leaving the rete testis.

Androgens↗