Effects of Aluminum Exposure on Serum Sex Hormones and Androgen Receptor Expression in Male Rats

The effects of aluminum (Al) exposure on reproductive functions of male rats were investigated. Forty male Wistar rats (4?weeks old) weighing 75-95?g were randomly divided into four groups and orally exposed to 0 (control group GC), 64.18 (low-dose group GL), 128.36 (middle-dose group GM), and 256.72 (high-dose group GH) mg/kg aluminum trichloride in drinking water for 120?days. The levels of testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were determined by radioimmunoassay. The androgen receptor (AR) expressions in testes were detected respectively by immunohistochemistry and time quantitative PCR. Results showed that the levels of T and LH in GM and GH were lower than those in GC (P??0.05). AR protein expressions in GM and GH were lower than those in GC (P?相似文献   

Impact of subchronic exposure to triclosan and/or fluoride on estrogenic activity in immature female rats: The expression pattern of calbindin‐D9k and estrogen receptor α genes

This study explored the influence of triclosan (TCS) in the absence and presence of sodium fluoride (NaF) on estrogenic activity and thyroid function of adolescent female rats. The results indicated that the individual exposure to TCS evoked a significant decline in T₃ and T₄ but the levels of estradiol, FSH, and LH were significantly elevated beside marked up regulation of calbindin‐D9k and estrogen α mRNA expression. On the other hand, the single exposure to NaF causes insignificant changes in thyroid hormones, but evoked a trend toward an increase in both estradiol and LH levels. No significant differences in the TSH level were recorded among the experimental groups. The joint exposure to TCS and NaF induced a significant improvement in thyroid and reproductive hormone levels. Overall, these findings revealed that exposure to TCS resulted in significant endocrine and reproductive alterations in immature female rats, while TCS + NaF coexposure resulted in lessening most effects.     

Bone loss in ovariectomized rats: dominant role for estrogen but apparently not for FSH

Estrogen deficiency as the sole factor underlying post‐menopausal osteoporosis was challenged, in light of reports that both follicular stimulation hormone (FSH) receptor and FSHβ knockout mice were resistant to bone loss, suggesting a detrimental role for FSH. We assessed whether lowering FSH levels by gonadotropin realizing (GnRH) analog decapeptyl in ovariectomized female rats (OVX) affects bone. Wistar‐derived 25 days old OVX female rats were injected for 10 weeks with estradiol‐17β (E₂), with GnRH analog (decapeptyl) or with both. FSH and luteinizing hormone (LH) serum levels were markedly increased in OVX rats, with smaller growth plates with disrupted architecture; heavy infiltration of bone marrow with numerous adipocytes and reduced thickness of cortical bone. In OVX rats treated with E₂, FSH, and LH levels were intermediate, the tibia was similar to that of intact rats, but there was reduced thickness of cortical bone. In decapeptyl treated OVX rats, FSH and LH levels were suppressed, the organization of growth plate and the trabecular bone were disrupted, and there were fewer proliferative and chondroblastic cells and a large adipocytes population in bone marrow, but an increased trabecular bone volume (TBV). In the E₂ + decapeptyl treatment, FSH and LH levels were suppressed, with partially restored growth plate architecture and improved TBV. In conclusion, E₂ deficiency is the dominant factor impairing bone loss in OVX and concomitant changes in FSH/LH levels achieved by decapeptyl have some modulating, though complex role in this setting. The role of high FSH levels in post‐menopausal bone loss requires further investigation using combined sub‐optimal doses of the different hormones. J. Cell. Biochem. 112: 128–137, 2011. © 2010 Wiley‐Liss, Inc.     

Effect of Selenium,Zinc, and Copper Supplementation on Blood Metabolic Profile in Male Buffalo (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>) Calves

Twenty male buffalo calves (15 months, 200.2 ± 9.75) were divided into four groups of five animals in each and fed diets without (T1) or supplemented with 0.3 ppm selenium (Se) + 40 ppm zinc (Zn) (T2), 0.3 ppm Se + 40 ppm Zn + 10 ppm copper (Cu) (T3), and 40 ppm Zn + 10 ppm Cu (T4) for 120 days, during which blood samples were collected on days 0, 40, 80, and 120. Concentrations of glucose, total protein, albumin, globulin, urea, uric acid, and creatinine were similar in all the four groups. The level of different serum enzymes viz. lactate dehydrogenase, alkaline phosphatase, glutamate pyruvate transaminase, and glutamate oxaloacetate transaminase, and hormones viz. T₃, T₄, testosterone and insulin were similar (P > 0.05) among the four groups but the ratio of T₄/T₃ was reduced (P < 0.05) in the groups (T2 and T3) where selenium was supplemented at 120th day of supplementation. It was deduced that supplementation of 0.3 ppm Se and/or 10.0 ppm of Cu with 40 ppm Zn had no effect on blood metabolic profile in buffalo calves, except the ratio of T₄ and T₃ hormone which indicates that selenium plays an important role in converting T₄ hormone to T₃ which is more active form of thyroid hormone.     

Effects of 17β-Estradiol and Vitamin E Treatments on Blood Trace Element and Antioxidant Enzyme Levels in Ovariectomized Rats

We investigated the effect of 17β-estradiol (E₂) alone and separately vitamin E treatment on trace element status of rats following an ovariectomic operation. Forty rats were equally divided into four groups: Group 1, control, non-ovariectomized rats; Group 2, (OVX) rats, ovariectomized under general anesthesia; Group 3, (OVX+E₂) rats, the group received a 40 μg kg⁻¹ subcutan dose of E₂ per day after ovariectomy; and Group 4, (OVX + E₂ + vitamin E) rats, received the same E₂ treatment, but with an additional 100 mg kg⁻¹ intraperitoneal dose of vitamin E per day after ovariectomy. At the end of the 30-day experiment, the rats were sacrificed and their blood was collected for the measurement of zinc, copper, iron, phosphorus, selenium, magnesium, calcium, manganese, and chromium; copper–zinc superoxide dismutase (SOD); manganese-superoxide dismutase (Mn-SOD); glutathione peroxidase (Se-GSH-Px); and catalase (CAT). The levels of zinc, copper, iron, phosphorus, selenium, calcium, chromium, and manganese and activities of SOD, Mn-SOD, Se-GSH-Px, and CAT were lower in the OVX than in the control group, but magnesium level was unaffected. However, zinc, copper, iron, phosphorus, selenium, calcium, chromium, and manganese levels and SOD, Mn-SOD, Se-GSH-Px, and CAT activities were higher under separate E₂ and E₂ + vitamin E treatments. The level of magnesium in the treated-OVX groups was not different than in the OVX group. In conclusion, E₂ treatment has an ameliorating effect on the trace element status in OVX, and this effect may be enhanced with the addition of vitamin E.     

Effects of Subchronic Aluminum Exposure on the Immune Function of Erythrocytes in Rats

This study assessed effects of aluminum (Al) exposure on the immune function of erythrocytes in rats. Forty male Wistar rats (5 weeks old) weighed 110–120 g were randomly allocated equally into four groups according to their weights and were orally exposed to 0, 64.18, 128.36, and 256.72 mg/kg body weight aluminum trichloride in drinking water for 120 days. Levels of erythrocytes C_3b receptor rate (RBC-C_3bRR), erythrocytes C_3b immune complex rosette rate (RBC-ICR), erythrocytes rosette forming enhancing rate (ERER) and erythrocytes rosette forming inhibitory rate (ERIR) were determined by the end of experiment. The three Al-treated groups had lower values of RBC-C_3bRR and ERER, and higher values of RBC-ICR and ERIR than those in control group. The levels of RBC-C_3bRR and ERER decreased, while the levels of RBC-ICR and ERIR increased with the increases of Al content in drinking water. The results suggest that the immune function of erythrocytes in rats is suppressed by Al exposure.     

Induction of G protein-coupled estrogen receptor (GPER) and nuclear steroid hormone receptors by gonadotropins in human granulosa cells

Estradiol and progesterone mediate their actions by binding to classical nuclear receptors, estrogen receptor α (ERα) and estrogen receptor β (ERβ) and progesterone receptor A and B (PR-A and PR-B) and the non-classical G protein-coupled estrogen receptor (GPER). Several animal knock-out models have shown the importance of the receptors for growth of the oocyte and ovulation. The aim of our study was to identify GPER in human granulosa cells (GC) for the first time. Moreover, the effect of different doses of gonadotropins on estrogen and progesterone receptors in the human ovary should be investigated as follicle stimulating hormone (FSH) and luteinizing hormone (LH) are also responsible for numerous mechanisms in the ovary like induction of the steroid biosynthesis. Human GC were cultured in vitro and stimulated with different doses of recombinant human FSH or LH. Receptor expression was analyzed by immunocytochemistry and quantitative real-time RT-PCR. GPER could be identified for the first time in human GC. It could be shown that high concentrations of LH increase GPER protein expression. Furthermore FSH and LH increased ERβ, PR-A and PR-B significantly on protein level. These findings were verified for high doses of FSH and LH on mRNA level. ERα was not affected with FSH or LH. We assume that gonadotropins induce GPER, ERβ and PR in luteinized granulosa cells.     

Effects of human chorionic gonadotropin combined with clomiphene on Serum E2, FSH,LH and PRL levels in patients with polycystic ovarian syndrome

ObjectiveEffects of human chorionic gonadotropin combined with clomiphene on serum E₂, FSH, LH and PRL levels in patients with polycystic ovarian syndrome were analyzed.Methods90 patients with polycystic ovarian syndrome treated from January 2015 to March 2016 were randomly and evenly divided into control group and observation group. Patients in the control group were only treated with clomiphene. On the basis of the treatment in control group, human chorionic gonadotropin was added in the treatment of observation group. The changes of E₂, FSH, LH, PRL levels were compared between two groups before and after the treatment. Clinical curative effects of patients in the two groups was evaluated. Adverse reactions during treatment in two groups were observed and recorded. The incidence of adverse reactions was calculated.ResultsSerum E₂, FSH, LH and PRL levels in the two groups decreased significantly after treatment compared with that before treatment. The difference is statistical significant (P < 0.05). After the treatment, E₂, FSH, LH and PRL levels in the observation group were lower than that in the control group and the difference is statistical significant (P < 0.05). Total effective rate was 64.44% in the control group and 93.33% in the observation group. There were statistically significant difference in clinical curative effects in the two groups (P < 0.05). Different degrees of adverse reactions were found in both groups during treatment, such as nausea, vomiting, anorexia, liver dysfunction. There were 2 cases of nausea, 2 cases of vomiting, 3 cases of anorexia and 1 case of liver dysfunction from the 45 patients in control group. The total incidence of adverse reactions was 17.78% (8/45). There were 1 case of nausea, 1 case of vomiting, 1 case of anorexia and no liver dysfunction from the 45 patients in observation group. The total incidence of adverse reactions was 6.67% (3/45). The total incidence of adverse reactions in the observation group was significantly higher than that in the control group and the difference was not statistically significant (P > 0.05).ConclusionCombined use of human chorionic gonadotropin can significantly reduce serum E₂, FSH, LH and PRL levels, improve clinical curative effects and reduce the incidence of adverse reactions. Human chorionic gonadotropin has high application value on the treatment of polycystic ovary syndrome.     

Concentrations of gonadotropins,estradiol and progesterone in sows selected on an index of ovulation rate and embryo survival

The objective of this study was to determine concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), progesterone (P₄) and 17β-estradiol (E₂) in sows from a line selected on an index which emphasized ovulation rate (Select) and from a control line. A further classification of the sows in each line was made according to the estimated number of ovulations during an estrous cycle. Sows in the Select line were ranked into a high (HI) or low group (LI) when their estimated number of ovulations were 25 or more and 14 to 15, respectively. Sows of the control line were classified into groups as high (HC) or low (LC) when the estimated values for ovulation rate were 14–15 and 8–9 ovulations, respectively. Blood samples were collected every 12 h during a complete estrous cycle and samples were analyzed for concentrations of FSH and LH. Samples collected every 24 h were assayed for P₄ and E₂. Mean concentrations of FSH, LH, P₄ and E₂ did not differ (P>0.10) between lines or between HI and LI or HC and LC groups. Selection of pigs for ovulation rate and embryonal survival did not affect concentrations of FSH, LH, P₄ and E₂ in sows during the estrous cycle.     

Prostacyclin (PGI2) effets on anterior pituitary hormones in the rat in vivo

Intravenous injection of 600 μg PGE₂ or PGI₂ significantly increased serum LH and prolactin levels in estradiol treated ovariectomized rats. There was no effect on serum FSH concentration. PGE₂ and PGI₂ stimulated LH release in a non-dose dependent manner, while prolactin levels were positively correlated with the dose administered following PGI₂ treatment. 6-keto-PGF_1α at a comparable dose had no effect on pituitary hormone levels. Subcutaneous administration of 1 mg/kg or 60 mg/kg PGI₂ for seven days significantly depressed serum LH level both in male and female rats. These doses had no effect on serum FSH or prolactin levels.     

Factors influencing resumption of meiotic maturation and cumulus expansion of porcine oocyte-cumulus cell complexes in vitro

The present study was undertaken to examine effects of various combinations of epidermal growth factor (EGF), transforming growth factor-b?₁ (TGF-b?₁), follicle-stimulating hormone (FSH), luteinizing hormone (LH), androstenedione (A₄), and estradiol-17b? (E₂) on meiotic maturation and cumulus expansion in the pig using an in vitro model system. Oocyte-cumulus cell complexes (OCC) were cultured in the media containing the abovementioned agents for 24 hr and were observed for germinal vesicle breakdown (GVBD), indicative of initiation of meiotic maturation, and for expansion of their cumulus cells. Treatment with EGF significantly increased (P < 0.05) incidence of GVBD, with maximal stimulation occurring at 1 ng/ml (55% vs. 12% in the control). Concentrations of EGF as low as 100 pg/ml significantly stimulated GVBD over control (37% vs. 12%). Addition of EGF (1 ng/ml) and FSH (1.5 μg/ml) together and LH (2 μg/ml) and FSH (1.5 μg/ml) together resulted in significantly higher (P < 0.01) GVBD levels than were observed in response to EGF, FSH, or LH alone. Addition of E₂ (1 μg/ml) had no effect by itself but significantly decreased the incidence of GVBD in the presence of FSH and of LH + FSH. Addition of A₄ (1 μg/ml) significantly reduced the percentage of oocytes undergoing GVBD when added alone or with FSH. Although both EGF and LH stimulated cumulus expansion, FSH was more effective in stimulating cumulus expansion than EGF or LH. TGF-b?₁ had no effect on GVBD or cumulus expansion. These studies indicate that these hormones may have differing roles in oocyte maturation and that their interactions may be part of an intricate system regulating the maturation of oocytes during follicular development in vivo. © 1993 Wiley-Liss, Inc.     

Does neonatal androgen modulate uptake and retention of 3H-estradiol in gonadotrophs and lactotrophs?

Summary Castrated adult male and female and androgenized female rats (AS rats) were injected i.v. with ³H-estradiol (E₂). Nuclear uptake and retention of the ³H-steroid was examined in pituitary luteinizing hormone (LH) and prolactin (PRL) cells by the combined techniques of autoradiography and immunocytochemistry. About 80% of PRL cells were found to concentrate the radioactive steroid compound in all experimental groups, while 89%, 82% and 68% of LH cells were found to be labeled in AS rats, normal female and male rats, respectively. This suggests that there are subpopulations of LH or PRL cells that contain no or, if any, small numbers of E₂ receptor. Statistical analysis revealed that PRL cells take up more radioactivity than LH cells in male rats, while there is no significant difference between female and AS rats. Variations in E₂ uptake (coefficient of variation) was higher in LH cells than in PRL cells in male rats and in AS rats. In females, on the contrary, coefficient of variation was larger in PRL cells. Thus the characteristics of nuclear uptake and retention of estradiol in LH and PRL cells appear to be modulated in part by neonatal androgen since the pattern found in AS rats is different than that found in normal male and female rats.     

Plasma concentration changes in LH and FSH following electrochemical stimulation of the medial preoptic are or dorsal anterior hypothalamic area of estrogen- or androgen-sterilized rats.

Plasma concentraption changes in luteinizing hormone (LH) and follicle stimulation hormone (FSH) following elctrochemical stimulation (ECS) of the medial preoptic area (MPOA) or dorsal anterior hypothalamic area (DAHA) of estrogen-or androgen-sterilized rats were compared with normal proestrous rats in which spontaneous gonadotropin surges had been blocked with Nembutal (control). ECS of control rats, AST, and ESR provoked marked increases in FSH by 120 minutes and peak levels by 180 minutes poststimulation. No differenses were seen when ESR of ASR plasma levels were compared with control values or to each other (ESR vs. ASR). DAHA-ECS did not provoke a marked LH rise in ASR and ESR. MPOA-ECS of control, ASR, and ESR resulted in the release of LH and FSH. FSH peaked in all groups at 240 minutes but at 120 and 180 minutes poststimulation plasma FSH levels were greater in ASR and ESR than controls. FSH in ESR was significantly higher (p. 05) at 120 and 240 minutes poststimulation. LH was elevated in all groups following MPOA-EDS but in ESR markedly greater LH levels were obtained at 60 and 180 minutes compared with controls or ASR. Preoptic stimulation of progesterone-treated ASR (P-ASR) did not induce greater release of FSH than in control, ASR, ESR, or P-ESR. Stimulation of P-ASR resulted in greater plasma LH rise by 60 minutes which was greater than ASR, P-ASR, ESR, or controls, followed by decreased levels to baseline in P-ESR. MPOA-ECS controls ovulated (8-13 eggs) whereas neither ASR nor ESR Fallopian tubes contained eggs the following morning. No DAHA-stimulated groups ovulated. All P-ASR but no P-ESR ovulated after MPOA-ECS. It is concluded that while exposure of neonatal female rats to estrogen renders them more sensitive than ASR to preoptic stimulation, the ovaries of these amimals are much less responsive to the gonadotropin released into plasma than are those of ASR or normal rats.     

Tracking the Ovarian Cycle in Black-and-Gold Howlers (<Emphasis Type="Italic">Alouatta caraya</Emphasis>) by Measuring Fecal Steroids and Observing Vaginal Bleeding

A better understanding of a species’ reproductive physiology can help conservation programs to manage primates in the wild and develop assisted reproductive technologies in captivity. We investigated whether measurements of fecal progestin and estrogen metabolites obtained by a radioimmunoassay could be used to monitor the ovarian cycle of Alouatta caraya. We also compared the occurrence of vaginal bleeding with the hormone profiles. We collected fecal samples from 3 adult and 1 subadult captive female over 5 mo and performed vaginal cytology for the adults. The interval between fecal progestin surges in the adult females was 19.11 ± 2.14 d (n = 18 cycles). Fecal progestin concentrations remained at basal values for 9.83 ± 2.21 d (n = 18) and rose to elevated values for 9.47 ± 0.72 d (n = 19). The subadult female showed basal levels of fecal estrogen and progestin concentrations throughout the study, suggesting that our hormone measurements are valid to monitor the ovarian cycle. Bleeding periods coincided with basal levels of fecal estrogens and progestin at intervals of 19.8 ± 0.9 d and lasted for 4.1 ± 1.0 d. Although we obtained these data from only 3 individuals, the results indicate that this species likely has a menstrual-type ovarian cycle. These data provide the first endocrine profile for the Alouatta caraya ovarian cycle and are similar to results obtained for other howler species. This similarity is important for comparative studies of howlers, allowing for a better understanding of their reproductive physiology and contributing to a critical information base for managing Alouatta species.     

Effects of raloxifene and estradiol on bone turnover parameters in intact and ovariectomized rats

This study was designed to investigate effects of raloxifene (RLX) and estradiol on bone formation and resorption in intact and ovariectomized (ovx) rat models. In the intact model, a total of 24 adult female rats were divided into three groups: Controls subcutaneously received saline alone. RLX (2 mg/kg) and estradiol (30 μg/kg) were injected to two groups of animals for a period of 6 weeks at two daily intervals. In the second model, rats (n = 24) were ovx and allowed to recover for a period of at least 3 weeks. Control group received vehicle alone. Remaining rats were divided into two groups and injected with RLX (2 mg/kg) and estradiol (30 μg/kg) for 6 weeks. Urine samples were collected from all animals 24 h after the last drug administration. Urinary deoxypyridinoline (DPD) was measured by ELISA. Serum parathyroid hormone (PTH), calcitonin, and osteocalcin levels were measured by immunoradiometric method. Serum concentrations of alkaline phosphatase (ALP), Ca, and inorganic phosphate were determined by enzymatic–colorimetric method. Lumbar vertebrae (L2) of all animals were dissected out and processed for histopathological evaluation. Removal of ovaries significantly elevated urinary DPD levels (p < 0.01) compared with intact controls. Treatment of both intact and ovx rats with estradiol resulted in significant decreases (p < 0.01) in DPD values. RLX administration had no significant effect in the intact rats, but it remarkably reduced bone turnover in the ovx animals (p < 0.001). Both estradiol and RLX produced conflicting effects on serum ALP, osteocalcin, and PTH levels in both animal models. These findings suggest that RLX exerts its protective effects by reducing bone resorption, similar to that of estradiol, in ovx rats.     

Experimental simulation of an estrous cycle — gonadotropin surges in estradiol‐infused ovariectomized rats

Abstract

Dynamic relations between the circulating estrogen and the hypophyseal gonadotropin secretion in the estrous cycle were investigated by replacing the ovaries by an infusion pump in freely moving rats. Female rats were ovariectomized in the morning at certain stages of the 4‐day estrous cycle, and simultaneously infused with estradiol (E₂) at a constant rate of 0.35 ng/min up to 120 h through a cannula chronically inserted into the jugular vein. They were killed at 6 h‐intervals. Rats ovariectomized at the second day of diestrus and at estrus showed a sharp rise in LH 36 h and 84 h, respectively, after the initiation of E₂ infusion, when the proestrous surge would occur in normal rats. During the other periods, blood levels of LH were very low, exhibiting a small daily rise in the evening. Similarly ovariectomized rats infused with vehicle only showed a gradual rise of gonadotropin secretion, never reaching the surge level. Rats ovariectomized at proestrus and infused with E₂ showed a LH surge 12 h later as expected. However, surge‐like LH secretions followed every evening thereafter. Thus, the constant supply of E₂ alone could simulate at least one 4‐day cyclic LH surge in ovariectomized rats. E₂ infusion caused a daily peak of FSH synchronized with the LH rises, but could not suppress the post‐operative hypersecretion. It is discussed that if the suppressing effect of progesterone endogenously secreted from the ovaries is cleared, a circadian pattern of the LH/FSH surge may appear under the signal from the cerebral clock mechanism and the effect of circulating estrogen. The failure to suppress the FSH hypersecretion by E₂ might indicate the involvement of inhibin in the regulatory mechanism. Time‐course changes in uterine and vaginal weights are also dealt with and discussed in relation to the constant E₂ exposure.     

Concentrations of steroids in the utero-ovarian vein blood,serially collected from the two sides of individual baboons,during the follicullar phase

The purpose of this study was to determine and compare the follicular phase steroid hormone secretion into the utero-ovarian vein by the ovary with a dominant follicle and the contralateral ovary in the same baboon. Serial utero-ovarian vein blood from both sides was collected in 25 baboons by the use of a laparoscope on alternate days, starting on day 1 or 3 of the cycle and continuing through 2 to 3 days post-ovulation. Approximately 3–4 days before the day of expected ovulation, samples were collected at 8-hr intervals. Steroids estradiol (E₂) and progesterone (P) were measured in all utero-ovarian vein plasma by radioimmunoassay. In the peripheral plasma, E₂, P, LH, and FSH measurements were carried out. Concentrations of steroids were significantly higher on the side of the ovulating ovary by day 5 before ovulation. Individual plots however, indicated that some baboons may establish the dominant side as early as day 11 before ovulation. The preovulatory gonadotropins had a differential effect on the two ovaries. For example, E₂ values on the ovulatory side ovary declined after increases in LH/FSH, whereas on the contralateral side these values had increased. Both sides showed increases in the level of P with the increases in LH. The mean interval from E₂ peak to LH peak was 24 hrs and LH peak to ovulation was 24 hrs.     

Effect of gonadotropin-releasing hormone,stage of sexual maturation and 6-methoxybenzoxazolinone on plasma gonadotropins,ovarian development and uterine weight in prepuberal gilts

Two experiments were conducted with prepuberal gilts at 60, 120 and 160 days of age to a) determine the effect of 6-methoxybenzoxazolinone 6-MBOA) on reproductive plasma hormone concentrations and organ development, and b) determine how plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH) concentrations before and after injection of gonadotropin-releasing hormone (GnRH) or 6-MBOA varied in relation to ovarian development. In Exp. 1, 12 gilts were used in a 4×4 Latin square design. Four gilts/age group were injected once with: 1) vehicle, 2.5% propylene glycol in 50% ethanol, 2) 2 μg of GnRH/kg body weight (BW), 3) 0.2 mg of 6-MBOA/kg BW, and 4) 2 mg of 6-MBOA/kg BW on four successive days in random order. Blood was collected via indwelling vena cava catheters. Injection of GnRH into gilts increased plasma FSH and LH at each age compared with vehicle (P<0.05). Hormone profiles for FSH and LH differed among age groups (P<0.01), but area under curves did not differ significantly among age groups. Injection of 6-MBOA did not significantly affect plasma FSH and LH. Plasma FSH and LH before the GnRH injection or on days when GnRH was not injected were greater at 60 than at 120 and 160 days (FSH, 128 vs 54 and 42 ng/ml; LH, 0.38 vs 0.16 and 0.13 ng/ml for 60, 120 and 160 days, respectively (P<0.05). In Exp. 2, vehicle, 0.2 or 2 mg of 6-MBOA/kg BW were injected once daily for 7 days in 19 gilts. Injections of 6-MBOA had no detectable effects on gonadotropin secretion, ovarian development or uterine weight. Between 60 and 120 days of age, vesicular follicles developed, ovarian weight increased 20-fold, and uterine weight increased 10-fold (P<0.05); basal concentrations of plasma FSH and LH decreased three- and twofold, respectively.     

Pituitary hormones and growth retardation in rats raised at simulated high altitude (3800m).

Growth and the endocrine status of the pituitary and thyroid glands were studied in rats born and raised in a hypobaric chamber at a simulated high altitude of 3800 m (SHA); comparisons were drawn with similar rats at sea level. From birth until 40 days of age, SHA rats weighed significantly less than controls with the most striking growth impairment found in female SHA rats. Relative organ weights of anterior pituitary glands, ovaries and uteri from 40-day-old female SHA rats were significantly less than controls. Pituitary content of growth hormone (GH) was reduced in 40-day-old female SHA rats while the content of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were significantly increased over sea level controls. Plasma levels of GH, LH, FSH and thyrotropin (TSH) and pituitary TSH levels did not differ from control values. However, thyroidal uptake of 131I and plasma protein-bound 131I were significantly reduced in SHA rats as compared with controls. It is suggested that (1) the continuous exposure of developing female rats to hypoxia significantly impairs pituitary function and reproductive maturation, and (2) that despite other environmental factors acting on the developing organism at high altitude, growth retardation in rats born and raised at high altitudes is primarily a consequence of hypoxia.