Acute effects of unilateral sectioning the superior ovarian nerve of rats with unilateral ovariectomy on ovarian hormones (progesterone,testosterone and estradiol) levels vary during the estrous cycle

The present study analyzed the participation of the left and right superior ovarian nerves (SON) in regulating progesterone, testosterone, and estradiol serum levels in unilaterally ovariectomized rats on each day of the estrous cycle. For this purpose, ovarian hormone concentrations in serum were measured in animals with either sham-surgery, unilateral ovariectomy (ULO), unilateral sectioning of the SON, or sectioning of the SON innervation of the in situ ovary in rats with ULO.     

Effect of unilateral ovariectomy on compensatory ovarian hypertrophy, peripheral concentrations of follicle-stimulating hormone and luteinizing hormone, and ovarian venous concentrations of estradiol-17 beta in prepuberal gilts

A study was designed to characterize the compensatory ovarian response to unilateral ovariectomy (ULO) in prepuberal gilts and to investigate further the mechanisms involved in compensatory ovarian hypertrophy (COH). Forty-eight crossbred gilts were sham ovariectomized (Sham) or unilaterally ovariectomized at 130 days of age (Day 0). Remaining ovaries in ULO gilts were removed and Sham gilts were bilaterally ovariectomized 2, 4 or 8 days later. A peripheral blood sample was taken before surgery and ovarian venous blood samples were taken before removal of each ovary. Serum estradiol-17 beta (E2) concentrations were determined. Mean wet and dry ovarian weights per ovary on Day 2 for ULO and Sham gilts were 3.4 versus 2.8 and 0.26 versus 0.24 g, respectively. Those weights on Days 4 and 8 were greater (P less than 0.01) for ULO than Sham gilts. Follicular fluid weight per ovary was greater (P less than 0.05) for ULO than Sham gilts on Days 2, 4 and 8. Ovarian venous E2 concentrations were greater (P less than 0.01) for ULO than for Sham gilts on Days 2 and 4 but were similar on Day 8. In a second experiment, 42 prepuberal gilts 130 days of-age were subjected to Sham (n = 18), ULO (n = 18) or bilateral ovariectomy (BLO; n = 6) to evaluate follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion immediately after surgical treatment. Release of FSH within the first 24 h was greater for BLO than ULO and for ULO than Sham gilts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ipsilateral vagotomy to unilaterally ovariectomized pre-pubertal rats modifies compensatory ovarian responses

The present study evaluates the participation of the vagus nerve in pre-pubertal rats with unilateral ovariectomy on puberty onset, and on progesterone, testosterone and estradiol serum levels, and the compensatory responses of the ovary. Unilateral vagotomy did not modify the onset of puberty in unilaterally ovariectomized rats. Ovulation rates of animals with the left vagus nerve sectioned and the left ovary in-situ was lower than in rats with only unilateral ovariectomy. Sectioning the left vagus to 32-day old rats with the left ovary in-situ resulted in lower compensatory ovarian hypertrophy than in rats with right unilateral ovariectomy. Twenty-eight or 32-day old animals with sectioning of the right vagus nerve and the right ovary in situ showed higher compensatory ovulation. Twenty-eight -day old rats with the right ovary in situ had higher progesterone and testosterone levels than animals of the same age with the left ovary in-situ. Compared to animals with the right ovary in situ, animals treated at 32-days of age, sectioning the ipsi-lateral vagus nerve resulted in higher progesterone levels. Higher progesterone levels were observed in 28- and 32 days old rats with the left ovary in situ and left vagus nerve sectioned. Thirty-two day old animals with the right ovary in situ and right vagus nerve sectioned had higher progesterone levels than rats of the same age with the left ovary in situ and left vagus nerve sectioned. Left vagotomy to 28-day old rats with the left ovary in situ resulted in higher testosterone levels, a reverse response to that observed in animals with sectioning of the right vagus and the right ovary in situ. Thirty-two day old rats with the left ovary in situ and left vagus nerve sectioned showed lower testosterone levels than animals without vagotomy and with the left ovary in situ.     

Compensatory ovulatory mechanisms operative after first ovulation in rats unilaterally ovariectomized prepubertally

Ovarian steroid contents and serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin were measured during the days after first ovulation in rats unilaterally ovariectomized in late prepuberty. In addition, follicle counts were made at second estrus and second metestrus. During the cycle following first ovulation, ovarian estradiol contents in unilaterally ovariectomized (ULO) rats were significantly increased as compared to intact rats on the day of metestrus, on diestrus 1 and on second estrus. Ovarian progesterone was significantly increased on the days of metestrus, on diestrus 1, second proestrus and second estrus, but no differences were seen in ovarian androgen contents. After ULO there was an indication of an augmented FSH surge at the first and the second ovulation. Follicle counts revealed that the total number of healthy as well as of atretic antral follicles on the day of second estrus was significantly increased after ULO, due to increased numbers of the smallest antral follicles. At second metestrus the number of larger antral follicles (350-500 micron 3) and the total number of healthy antral follicles was higher after ULO. It is concluded that the compensatory process after ULO involved increased recruitment of small antral follicles. Activities in the remaining ovary were not simply doubled but a new hormonal balance was established.     

Unilateral ovariectomy increases loss of primordial follicles and is associated with increased metestrous concentration of follicle-stimulating hormone in old rats.

The primary objective of these studies was to determine whether unilateral ovariectomy (ULO) would affect rate of loss of primordial follicles. In experiment 1, retired breeder rats, unilaterally ovariectomized and maintained on the experiment for 90 days after surgery, had fewer (p less than 0.01) primordial follicles per ovary than sham-operated controls of the same age. The purpose of experiment 2 was to determine whether time after ULO or age of rats was the critical factor necessary for increased loss of primordial follicles found after ULO in experiment 1. It was found that age was more important than time: when ULO was performed at 30 days of age, the number of primordial follicles did not decrease in ULO rats compared to controls (p greater than 0.05) before 250 days of age. Concentrations of FSH during metestrus were not greater (p greater than 0.05) in ULO rats than in controls until rats were 250 days old. There were also fewer (p less than 0.05) growing follicles per ovary in ULO than in sham-operated rats at 250 days of age. It is concluded that ULO can increase the loss of primordial follicles, but only in old rats (greater than or equal to 250 days of age).     

Evidence that the anterior hypothalamus contributes to the control of tonic secretion of follicle-stimulating hormone in the female rat

A horizontal knife cut was placed between the dorsal anterior hypothalamic area (DAHA) and the medial basal hypothalamus to examine the role of the DAHA in the selective secretion of follicle-stimulating hormone (FSH) following unilateral ovariectomy (ULO) and bilateral ovariectomy of the rat. Complete cuts markedly attenuated the increase in FSH observed 8 h after ULO, whereas incomplete or sham cuts did not. Concentration of luteinizing hormone (LH) did not increase in any group. These cuts also blocked the prolongation of estrous FSH secretion observed in long-term hemicastrated rats, since FSH levels on estrus were significantly lower in rats with complete cuts than in those rats given sham or incomplete cuts. In contrast, neural surgery had no effect on proestrous FSH concentrations. Finally, when FSH levels were monitored 2 days after bilateral ovariectomy, the postcastration rise in FSH was not altered by any neurosurgical procedures. These results support the hypothesis that a neural system originating in, or passing through, the DAHA is necessary for the selective increase in FSH following ULO.     

Circulating radioimmunoassayable inhibin during periods of transient follicle-stimulating hormone rise: secondary surge and unilateral ovariectomy

We have measured changes in circulating immunoreactive (ir-) inhibin in male and female rats using an RIA with an antiserum raised against porcine inhibin alpha (1-26)-Gly-Tyr. The same synthetic peptide was used for standards and for the preparation of tracer. Serum ir-inhibin levels were significantly higher in intact female than in intact male rats (p less than 0.001). Immunoreactive inhibin was significantly reduced in both sexes 24 h after bilateral gonadectomy (p less than 0.0001). Unilateral ovariectomy (ULO) of female rats on metestrus caused a transient decrease in serum inhibin 8 h after surgery, but levels were not significantly different from those of sham-operated controls at later times after surgery. Increases in serum FSH and LH were observed for 8-18 h after ULO. Serum ir-inhibin levels were also measured on the early morning of estrus during the secondary FSH surge. At this time, ir-inhibin levels were low, while FSH levels were high and LH levels were low. These results show that serum ir-inhibin levels in rats are decreased at times when serum FSH levels are high.     

Effect of reduced ovarian tissue on cyclicity, basal hormonal levels and follicular development in old rats

Reduction of the number of growing follicles was proposed to contribute to the decline in reproductive performance with aging (Butcher and Page, 1981). To investigate the effects of a reduced number of follicles, rats which maintained regular estrous cycles at greater than 1 yr of age had either unilateral ovariectomy (ULO) or control surgery. Irregular estrous cycles and periods of constant estrus were more frequent during a period of 90 days after ULO than in controls. Follicle-stimulating hormone (FSH) concentration in plasma collected at 0900-1100 h of the metestrus nearest to 20, 50, and 90 days after surgery was increased by ULO; in both treatment groups, FSH increased between 20 and 90 days. Compensation in ovarian weight and number of corpora lutea had occurred by 90 days after ULO. Estradiol, estrone and luteinizing hormone (LH) concentrations did not change with time or treatment. Numbers of small, medium and large antral follicles per ovary at metestrus were increased by ULO, while the number of follicles per rat was decreased. It was concluded that the reduction in ovarian tissue (which decreased the number of growing follicles) resulted in an elevation of basal FSH followed by irregularity in estrous cycles.     

Effect of unilateral ovariectomy and subsequent ovum implantation in mice.

Unilateral ovariectomy (ULO) was done on any stage of the cycle and the animals were mated within day 1 to day 21 to observe the acute and long term effect of ULO on ovum implantation. Implantation reduced in proportion to single ovary if the animals were mated within 24 hr of ULO. Increase in ovarian weight along with an increase in implantation number continued in mated mice and reached at peak on day 19-21 of ULO (sacrificed after 6 days i.e., 25-27 days of ULO). After ULO the remaining ovary compensated within day 5-6 of ULO even during pregnancy. Ovarian histology showed stimulation of small antral follicles in mice mated on day 3 of ULO (sacrificed after 6 days i.e., day 9 of ULO) along with a decrease of large antral follicles and pre-antral follicles. Preantral follicles were at peak on day 12-14. Large antral follicles attained a peak on day 4 which slowly decreased. The occurrence of implantation in such ULO conditions are discussed.     

Follicle stimulating hormone secretion and compensatory ovarian hypertrophy in prepubertal ewes

A study was conducted to determine the effect of unilateral ovariectomy (ULO) on follicle stimulating hormone (FSH) secretion and compensatory ovarian hypertrophy in prepubertal ewes. Thirty-three ewe lambs were allotted according to age and weight to a control (C) or ULO group. In the C group, a sham ovariectomy was performed on day 0 and both ovaries were removed on day 7. In the ULO group, one ovary was removed on day 0 and the remaining ovary was removed on day 7. Blood samples were collected from the jugular vein via venipuncture at 0, 6, 12 and 24 hours after the time of sham surgery or ULO (day 0). Subsequent samples were collected daily until day 7, and all samples were assayed for FSH and LH. Unilateral ovariectomy increased (P<0.01) ovarian weight and follicular fluid weight; however, lyophilized ovarian weight was similar for both groups. Within the ULO group, removal of the ovary having the largest follicle(s) did not prevent an increase in ovarian weight or follicular fluid weight of the remaining ovary. Unilateral ovariectomy had no effect on the total number of follicles (1 to 6 mm) per ovary; however, the number of large (5 to 6 mm) follicles per ovary was increased (P<0.05) following ULO. By 12 hours after ULO there was a transient increase (P<0.05) in the circulating concentrations of FSH. Circulating concentrations of luteinizing hormone (LH) were either low or undetectable in these prepubertal ewes and no LH response was observed following ULO. These results indicate that compensatory ovarian hypertrophy in ULO prepubertal ewes is accompanied by a transient rise in circulating FSH concentrations.     

The differing responsiveness of the anterior- and the middle-anterior hypothalamic area to estradiol benzoate implant: inhibition of compensatory ovarian hypertrophy.

Estradiol benzoate (E2) was chronically implanted, unilaterally or bilaterally, for about 30 days in the anterior (A-AHA) or the middle (M-AHA) portion of the anterior hypothalamic area (AHA) of unilaterally ovariectomized (ULO) and intact cyclic rats. E2 unilaterally implanted in the A-AHA partially blocked and bilaterally implanted totally blocked compensatory ovarian hypertrophy (COH) in response to ULO. E2 implanted in the M-AHA induced ovarian atrophy in ULO rats. In M-AHA E2 implanted rats, ovulation was completely inhibited, vaginal smears became persistently cornified, serum FSH was drastically suppressed to 23-24% of the estrous level, LH was unremarkably changed. These effects were less pronounced when the implant was place in the A-AHA, i.e., ovulation was partially blocked only with bilateral implantation, vaginal cycles were irregular, serum FSH was suppressed to 66% and 44% of the estrous level after unilateral and bilateral implantation, respectively, LH was rather unchanged. Uteri were neither atrophic whether the implants was placed in the A-AHA or in the M-AHA. In normal cyclic rats, the effects of E2 implantation in the two areas were similar to those observed in ULO rats, except that the effects were evident even after unilateral implantation since the brain had not been compensated. The results allowed to indicate a functional subdivision of the ventral AHA, at least into the A-AHA and the M-AHA. The M-AHA was experimentally elucidated to be more estrogen sensitive than the A-AHA for monitoring of serum FSH, and was suggested to be involved in the episodic secretion of FSH. The inhibitory effect of estrogen on COH may primarily be mediated through the M-AHA and secondarily through the A-AHA.     

SD雌性大鼠性发育早期性器官等脏器和性激素的动态变化

目的探讨正常SD雌性大鼠性成熟前不同日龄段的脏器与促黄体生成素（LH）、促卵泡素（FSH）、雌二醇（E2）等性激素的变化及其关系。方法从生产群中取出60窝密度状态一致的SD大鼠,在不同日龄随机选取雌性大鼠,检测15、25、32、40日龄时大鼠体重、主要脏器指数,子宫、卵巢组织变化和15、25、32、40、60日龄大鼠血清LH、FSH、E2水平。结果记录了SD雌性大鼠性成熟前各脏器指数和卵巢、子宫组织变化,结果显示大鼠卵巢、子宫的增长速度大于体重的增长,而其他脏器增速大都小于体重的增长。本研究还记录了血清LH、FSH、E2水平在不同日龄段的变化规律,表明血清LH、E2浓度在32日龄时出现较为明显升高。结论不同日龄大鼠脏器指数的动态变化提示大鼠性器官在性发育早期得到机体的优先发育。血清LH、E2水平在32日龄时有了明显升高,提示性腺轴功能已经激活。60日龄大鼠血清性激素水平的波动类似于动情周期的规律性变化,推测大鼠在60日龄前即已进入性成熟,这些结果将为大鼠性发育的相关研究提供重要的参考数据。     

Changes in rabbit corpus luteum progesterone secretion and cellular morphology following unilateral luteectomy or ovariectomy.

The objective of this study was to determine whether removal of corpora lutea (CL) from one ovary (unilateral luteectomy; ULL) or removal of the entire ovary (unilateral ovariectomy; ULO) of pseudopregnant rabbits would cause compensatory growth and progesterone production by the contralateral ovary. Pseudopregnancy was induced in rabbits with hCG (Day 0). On the first day of pseudopregnancy, one group of rabbits received a sham operation (controls), another group underwent ULL, and a third group underwent ULO. On Day 11 of pseudopregnancy, each rabbit underwent laparotomy, the ovarian artery and vein were cannulated, and the ovary(ies) was removed and perfused in vitro for 6 h. The mean CL weight increased by 33% in the ULL group and by 28% in the ULO group as compared to sham-operated controls. Peripheral estradiol and progesterone levels in sham-operated control, ULL, and ULO groups were similar. Ovarian venous estradiol levels were similar in the control and ULL groups, but were significantly increased in the remaining ovary of the ULO group. Both ovarian venous progesterone in vivo and progesterone secretion in vitro increased significantly in contralateral ovaries from ULL and ULO rabbits as compared to sham-operated controls. Progesterone secretion by ovaries perfused in vitro increased significantly in the contralateral ovary of the ULL and ULO groups. Mean number of luteal cells per CL increased significantly in the ULL group, but not in the ULO group. In contrast, luteal cell volume increased significantly in the ULO, but not in the ULL group. The stimuli responsible for increased progesterone production following ULL and ULO result in morphological changes in the remaining CL.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of frozen ovarian autografts on compensatory ovulation and steroid production in unilaterally ovariectomized rats.

In the present study rats were unilaterally ovariectomized (ULO) and the surgically removed ovary was frozen for 13 days. After allowing the remaining ovary to compensate with respect to number of ova shed, the frozen graft was thawed and transplanted subcutaneously to determine the effect on ovulation number, cycle length, uterine weight, ovarian weight and plasma levels of estradiol-17beta (E2) and progesterone. Rats ULO at 45 days of age, which received an autograft 13 days later, had a decrease in the number of eggs shed as compared to control ULO rats (6.4 +/- 0.8 vs. 11.1 +/- 0.9 eggs, respectively) and a decrease in plasma E2 (14.5 +/- 1.7 VS. 21.0 +/- 1.5 PG/ML, respectively). No differences were observed in progesterone concentration, uterine weight, ovarian weight or cycle length. In contrast, rats ULO at 31 days of age, which received an autograft 13 days later, showed no differences in comparison to control ULO rats. Castrates which received ovarian autografts developed cycling vaginal smears and had increased E2 (31.9 +/- 4.3 pg/ml) and decreased progesterone (18.3 +/- 1.9 ng/ml) levels. Since ULO animals with autografts shed fewer ova, the present study demonstrates that the amount of ovarian tissue influences ovulation number either by utilization of gonadotropins or by an, as yet, undefined mechanism.     

Unilateral ovariectomy restores ovulatory cyclicity in rats with a polycystic ovarian condition

An acyclic polycystic ovarian condition can be induced in adult rats with a single injection of estradiol valerate (EV). The ovaries are small and contain multiple cystic follicles and no new corpora lutea. In the early stages of the condition, both basal plasma luteinizing hormone (LH) and LH responses to luteinizing hormone-releasing hormone (LHRH) are attenuated. Plasma androgens are indistinguishable from normal controls. The present study examines the effect of unilateral ovariectomy (ULO) on this condition. Removal of one cystic ovary results in almost immediate resumption of vaginal cyclicity that persists for at least 3 wk. At 1 or 3 wk after ULO the remaining ovary contains fresh corpora lutea, appears histologically normal, and is significantly heavier than the cystic ovary removed at ULO, indicative of compensatory hypertrophy. Despite the resumption of apparently normal cyclic function, basal plasma LH concentrations and LH responses to LHRH are not significantly better than those in intact animals with polycystic ovaries. Thus, the previously polycystic ovary is fully capable of normal ovulatory function despite obvious impairments in the hypothalamo-pituitary axis. Since ovulatory function resumes on a background of continued poor pituitary responsiveness, the primary defect, which ULO corrects, is probably at the hypothalamic level. Finally, the cystic ovary clearly contributes to the hypothalamic aberration to which it subsequently responds.     

Follicle-stimulating hormone secretion in monosodium glutamate-lesioned rats: response to unilateral gonadectomy or porcine follicular fluid (inhibin)

The purpose of this study is to determine the acute response of pituitary FSH and LH release to unilateral gonadectomy in the MSG-treated rat, and to determine whether pFF (inhibin) can act effectively on pituitary FSH secretion in the MSG-lesioned rat. MSG (4 mg/kg B.W.) or saline was injected subcutaneously on postnatal days 2, 4, 6, 8, and 10 to male and female littermates which were used in the experiments after postnatal day 60. In the first experiment male and female littermates were bilaterally gonadectomized and bled serially for the next 72 h. At 0 h plasma FSH concentrations in MSG-treated rats were lower (p less than 0.05) than those in saline-treated controls, and for the 72 h immediately following bilateral gonadectomy FSH levels increased parallel to those of the controls, but after a significant delay. In the second experiment, MSG-treated male and female littermates were injected with 0.5 ml of pFF at several intervals following bilateral gonadectomy and decapitated 6 hours later. Injection of pFF significantly suppressed circulating FSH titers in all groups without affecting LH levels. In a third experiment, rats were unilaterally gonadectomized and blood samples were obtained at various intervals for 48 h. Following unilateral gonadectomy there was a significant transient increase in FSH levels in male or female MSG-treated rats as compared to their 0 h values; however, the absolute levels attained were barely equal to the basal concentrations observed in the saline-treated control rats. The conclusions from these data are: insufficient FSH secretion in response to unilateral gonadectomy may be responsible for the lack of compensatory gonadal hypertrophy in MSG-lesioned rats, pituitary response to inhibin is apparently unaltered by MSG toxicity, and the MSG-lesioned rat is a useful model to study the differential control mechanisms of FSH and LH secretion.     

Alterations in gonadotropin secretion and ovarian function in prepubertal gilts by elevated environmental temperature

The effect of chronic exposure to elevated environmental temperature on gonadotropin secretion and ovarian function was studied in prepubertal gilts. Gilts were maintained under control (15.6 degrees C) or elevated temperature (33.3 degrees C) conditions from 150 to 180 days of age. Endocrine and ovarian responses to bilateral (BLO), unilateral (ULO), and sham ovariectomy were evaluated between 175 and 180 days of age. During the 96-h sampling period after BLO, plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were suppressed in heat-stressed females. Similarly, elevated temperatures abolished the transient rise in FSH and subsequent follicular growth normally associated with ULO. In contrast, environmental treatment had no effect on the secretion of FSH and LH after sham ovariectomy, yet the number of small follicles was lower in gilts exposed to elevated temperatures than in females maintained under control conditions. These results indicate that a chronic exposure to elevated environmental temperature during pubertal development diminished the ability of the hypothalamo-hypophyseal axis to secrete FSH and LH, which had physiological consequences on follicular growth. When provided an appropriate stimulus (ULO), an acute period of FSH secretion and subsequent development of follicles failed to occur in females exposed to elevated temperatures. Consequently, we propose that delayed puberty in gilts during periods of elevated environmental temperatures is due, in part, to a diminished capacity for gonadotropin secretion.     

Involvement of the peripheral cholinergic muscarinic system in the compensatory ovarian hypertrophy in the rat

In the present experiments, unilateral ovariectomy (ULO) induced compensatory hypertrophy (COH) of the remaining rat ovary (60%-85% increase in ovarian weight, total proteins, and total RNA and DNA). An increased thymidine uptake preceded the organ enlargement. COH was inhibited by i.p.-administered muscarinic antagonist propantheline (dose-dependently) or botulinum toxin delivered locally to the ovary. The effects were reversed by bethanecol i.p. (a muscarinic agonist). In sham ULO animals, [3H]-scopolamine binding to ovarian membranes indicated the existence of muscarinic receptors (Kd 2.5 nM, Bmax 12 fmol/mg proteins, Hill 1.0). The ovarian 1,2-diacylglycerol (DAG) was 120-150 pmol/mg tissue and did not react to carbachol in vitro (50 microM). At 15 minutes after ULO, the [3H]-scopolamine binding was unchanged (Kd 2.6 nM, Bmax 12.6 fmol/mg tissue, Hill 1.0), but the ovarian DAG was increased (280-350 pmol/mg tissue) and increased further in response to carbachol (460-550 pmol/mg tissue). After ULO, ovarian DAG remained continuously responsive to carbachol. The ULO-induced DAG increase and enhanced susceptibility to carbachol were inhibited by the botulinum toxin or atropine pretreatments. Abdominal vagotomy done immediately before ULO also inhibited the ULO-induced DAG increase and DAG responsiveness to carbachol. However, when the vagotomy was performed 10 mins after ULO, the ovarian DAG remained responsive to carbachol in vitro. The data suggest that the peripheral cholinergic system, including the ovarian muscarinic receptors, stimulates COH. This is apparently associated with the ULO-induced coupling of the ovarian muscarinic receptors to phosphoinositide (PI) breakdown. Vagus plays a role in the occurrence of the changed muscarinic receptor-PI breakdown relationship in the remaining ovary.     

Systematic studies invalidate the neonatally androgenized rat as a model for polycystic ovary disease

As an adult, the neonatally androgenized (AZ) rat is anovulatory and exhibits follicular cysts. Thus, the AZ rat has been used as a model for polycystic ovary disease (PCO). However, its correlation with the human disease is not clear; so we have studied the AZ rat to determine its suitability as a PCO model. In Experiment I, reproductive hormones were measured at specific intervals between postnatal Days 15 and 90 in saline-treated and AZ rats. In Experiment II, AZ rats were treated with exogenous follicle-stimulating hormone (FSH) or subjected to unilateral ovariectomy (ULO) as analogies to therapies that have been used to treat human PCO. The results demonstrate that the luteinizing hormone (LH), FSH, testosterone (T), and estradiol (E2) concentrations of the AZ rat were not different from control values. Additionally, FSH therapy did not increase the E2 concentrations or the ovarian weight of the AZ rat. Furthermore, control and AZ rats exhibited similar post-ULO rises in FSH, but compensatory ovarian hypertrophy was not evident in the AZ rat. We conclude that 1) the hormonal and morphological patterns observed in the AZ rat do not correlate with those of PCO and 2) the androgenized rat does not provide an adequate model to study PCO.     

Hysterectomy in the rat: surgical disruption of the vascular channels reduces number of ova shed.

Cycling rats were hysterectomized and/or unilaterally ovariectomized (ULO) on day 2 (metestrus). Collateral blood supply to the remaining ovary via the uterine artery was left intact or disrupted. Animals were killed in metestrus after one complete estrous cycle. Control rats were also killed at this time. Counts of tubal ova revealed that intact rats ovulated an average of 4.4 +/- 0.4 eggs per ovary (N = 8). Following ULO, rats (N = 8) ovulated 9.6 +/- 0.2 EGGS. Ligation of the uterine artery decreased the number of eggs ovulated in ULO rats (N = 8) to 5.4 +/- 1.1. Hysterectomized rats (N = 8) ovulated 4.8 +/- 0.5 eggs per ovary. If the blood supply was disrupted, a reduction to 2.7 +/- 0.2 eggs per ovary occurred (N = 8). Hysterectomized and ULO rats (N = 8) ovulated 10.3 +/- 0.4 eggs from the remaining ovary but only 5.0 +/- 1.0 eggs if the collateral blood supply of the uterine artery was not intact (N = 10). The results demonstrate that disruption of the vascular channels during the surgical procedures of hysterectomy and/or ULO results in a reduction of the expected ovulation number.