Specific gut pathobionts escape antibody coating and are enriched during flares in patients with severe Crohn's disease.

OBJECTIVE: Patients with Crohn's disease (CD) exhibit great heterogeneity in disease presentation and treatment responses, where distinct gut bacteria and immune interactions may play part in the yet unresolved disease aetiology. Given the role of antibodies in the barrier defence against microbes, we hypothesised that gut bacterial antibody-coating patterns may influence underlying disease-mediated processes. DESIGN: Absolute and relative single and multicoating of gut bacteria with IgA, IgG1, IgG2, IgG3 and IgG4 in patients with CD and healthy controls were characterised and compared with disease activity. IgG2-coated and non-coated taxa from patients with severe CD were identified, profiled for pathogenic characteristics and monitored for enrichment during active disease across cohorts. RESULTS: Patients with severe CD exhibited higher gut bacterial IgG2-coating. Supervised clustering identified 25 bacteria to be enriched in CD patients with high IgG2-coating. Sorting, sequencing and in silico-based assessments of the virulent potential of IgG2-coated and bulk stool bacteria were performed to evaluate the nature and pathogenicity of IgG2-coated and non-coated bacteria. The analyses demonstrated IgG2-coating of both known pathogenic and non-pathogenic bacteria that co-occurred with two non-coated pathobionts, Campylobacter and Mannheimia. The two non-coated pathobionts exhibited low prevalence, rarely coincided and were strongly enriched during disease flares in patients with CD across independent and geographically distant cohorts. CONCLUSION: Distinct gut bacterial IgG2-coating was demonstrated in patients with severe CD and during disease flares. Co-occurrence of non-coated pathobionts with IgG2-coated bacteria points to an uncontrolled inflammatory condition in severe CD mediated via escape from antibody coating by two gut pathobionts.

[Proximal femoral nails antirotation and dynamic hip screws for fixation of unstable intertrochanteric fractures of femur: A meta-analysis].

OBJECTIVE: To evaluate the efficacy and safety of proximal femoral nail antirotation (PFNA) and dynamic hip screw (DHS) for unstable intertrochanteric fractures using meta-analysis. METHODS: The PubMed, Embase, Cocharane Central Register of Controlled Trials, Google Scholar, China Science and Technology Papers and Citation Database (CSTPCD) and China Journal Full-text Database (CNKI) were searched for published randomized controlled trials before January 1, 2019. Two researchers independently screened the literature in the light of the inclusion and exclusion criteria, evaluated the quality of the studies and extracted the data which were consisted of clinical efficacy indexes, such as incision length, operation time,intraoperative blood loss, weight-bearing time,fracture-healing time, Harris hip score and safety indicators like complications. Meta-analysis was performed with the Revman 5.3 software provided by Cochrane Community in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standard. RESULTS: Nine randomized controlled trials met the requirement with a total of 779 patients, of whom 383 were fixed with PFNA and 396 with DHS. Meta-analysis demonstrated that PFNA was associated with smaller surgical incision length [MD=-7.43, 95%CI (-9.31, -5.55), P<0.05], shorter operation time [MD=-22.76, 95%CI (-29.57, -11.95), P<0.05], less intraoperative blood loss [MD=-216.34, 95%CI (-275.18, - 157.49), P<0.05], earlier weight bearing after surgery [MD=-12.34, 95%CI (-17.71, -6.97), P<0.05], shorter fracture healing time [MD=-5.00, 95%CI (-7.73, -2.26), P<0.05], higher postoperative Harris hip score [MD=12.22, 95%CI (3.88, 20.55), P<0.05], higher rate of excellent Harris hip score [OR=3.56, 95%CI (1.44, 8.81), P<0.05] and lower incidence rate of postoperative complications [OR=0.48, 95%CI (0.33, 0.70), P<0.05], such as hip varus, wound infection, urinary tract infection, pulmonary infection, pressure sore, deep vein thrombosis, pulmonary embolism, heart failure and cerebral infraction when compared with DHS. No statistical difference was shown between the groups when it came to subgroup analysis by age. However, there was no significant difference (P>0.05) in the duration of hospitalization and the complications resulting in the occurrences of internal fixation loosening, such as femoral shaft fracture (during or post operation), internal fixation fracture, cut-out, displacement or retraction. CONCLUSION: Current published evidence supports the superiority of PFNA to DHS for unstable intertrochanteric fractures in terms of clinical efficacy. The conclusion was limited because of the relatively low quality of evidence with low strength of confidence. Large scale and high-quality randomized controlled trials are required to validate the safety of PFNA and DHS for unstable intertrochanteric fractures.

WASF3 provides the conduit to facilitate invasion and metastasis in breast cancer cells through HER2/HER3 signaling.

The WASF3 gene is overexpressed in high-grade breast cancer and promotes invasion and metastasis, but does not affect proliferation. The HER2/ERBB2/NEU gene is also frequently overexpressed in breast cancer, and has been shown to promote invasion and metastasis in these tumors. Here, we show that WASF3 is present in the HER2 immunocomplex and suppression of WASF3 function leads to suppression of invasion even in the presence of HER2 expression. Overexpression of both HER2 and WASF3 in non-metastatic MCF7 breast cancer cells promotes invasion and metastasis more significantly than either gene alone. HER2 forms homodimers as well as heterodimers with other HER family members and we now show that the ability of WASF3 to promote invasion is highly dependent on the HER2/HER3 heterodimer. The engagement of WASF3 with the HER2/HER3 complex facilitates its phospho-activation and transcriptional upregulation, which is facilitated by HER2/HER3 activation of JAK/STAT signaling. In breast cancer cells overexpressing HER2, therefore, WASF3 is specifically required to facilitate the invasion/metastasis response. Targeting WASF3, therefore, could be a potential therapeutic approach to suppress metastasis of HER2-overexpressing breast tumors.

RCAD/Ufl1, a Ufm1 E3 ligase, is essential for hematopoietic stem cell function and murine hematopoiesis.

The Ufm1 conjugation system is a novel ubiquitin-like modification system, consisting of Ufm1, Uba5 (E1), Ufc1 (E2) and poorly characterized E3 ligase(s). RCAD/Ufl1 (also known as KIAA0776, NLBP and Maxer) was reported to function as a Ufm1 E3 ligase in ufmylation (Ufm1-mediated conjugation) of DDRGK1 and ASC1 proteins. It has also been implicated in estrogen receptor signaling, unfolded protein response (UPR) and neurodegeneration, yet its physiological function remains completely unknown. In this study, we report that RCAD/Ufl1 is essential for embryonic development, hematopoietic stem cell (HSC) survival and erythroid differentiation. Both germ-line and somatic deletion of RCAD/Ufl1 impaired hematopoietic development, resulting in severe anemia, cytopenia and ultimately animal death. Depletion of RCAD/Ufl1 caused elevated endoplasmic reticulum stress and evoked UPR in bone marrow cells. In addition, loss of RCAD/Ufl1 blocked autophagic degradation, increased mitochondrial mass and reactive oxygen species, and led to DNA damage response, p53 activation and enhanced cell death of HSCs. Collectively, our study provides the first genetic evidence for the indispensable role of RCAD/Ufl1 in murine hematopoiesis and development. The finding of RCAD/Ufl1 as a key regulator of cellular stress response sheds a light into the role of a novel protein network including RCAD/Ufl1 and its associated proteins in regulating cellular homeostasis.

Collection of oocytes through transvaginal ovum pick-up for in vitro embryo production in Nanyang Yellow cattle.

The objectives of this study were to use ultrasound-guided transvaginal follicular aspiration to develop a technique for preservation of Nanyang Yellow cattle germ plasm. In Nanyang Yellow heifers, aspiration twice per week yielded a higher mean numbers of aspirated follicles, recovered oocytes and viable oocytes per session than once-weekly aspiration. Intriguingly, twice-weekly aspiration from Holstein heifers yielded a higher mean numbers of aspirated follicles, recovered oocytes and viable oocytes per session than in Nanyang Yellow heifers. Moreover, the oocyte recovery rate was significantly higher in Holstein heifers than in Nanyang Yellow heifers. Importantly, similar rates of embryos undergoing cleavage division were observed in Nanyang Yellow and Holstein, as was the number of viable day 8 blastocysts. These observations demonstrate that twice-weekly aspiration harvested the similar proportions of viable oocytes from Nanyang Yellow and Holstein follicles, and that twice-weekly aspiration yields a higher number of viable oocytes than once-weekly aspiration in Nanyang Yellow heifers. The results also suggest that the combination of ultrasound-guided transvaginal follicular aspiration and in vitro production is an effective and practical strategy for establishment of a germ plasm preservation programme for Nanyang Yellow cattle.

Stable and unstable transgene integration sites in the human genome: extinction of the Green Fluorescent Protein transgene in K562 cells.

In gene transfer experiments including gene therapy studies, expression of the integrated transgenes in host cells often declines with time. The molecular basis of this phenomenon is not clearly understood. We have used the Green Fluorescent Protein (GFP) gene as both a selectable marker and a reporter to study long-term transgene integration and expression in K562 cells. Cells transfected with plasmids containing the GFP gene coupled to the HS2 or HS3 enhancer of the human beta-globin Locus Control Region (LCR) or the cytomegalovirus (CMV) enhancer were sorted by either fluorescence-activated-cell-sorting (FACS) alone or FACS combined with drug selection based on a co-integrated drug resistance gene. The two groups of selected cells were subsequently cultured for long periods up to 250 cell generations. Comparison of long-term GFP transgene integration and expression in these two groups of cells revealed that the K562 genome contains two types of transgene integration sites: i) abundant unstable sites that permit transcription but not long-term integration of the transgenes and thus eliminate the transgenes in 60-250 cell generations and ii) rare stable sites that permit both efficient transcription and long-term stable integration of the transgenes for at least 200 cell generations. Our results indicate that extinction of GFP expression with time is due at least in part to elimination of the gene from the host genome and not entirely to transcriptional silencing of the gene. However, long-term, stable expression of the transgene can be achieved in cells containing the transgene integrated into the rare, stable host sites.

Effects of adrenergic antagonists on LH surge in short-term ovariectomized-steroids-primed rats.

Characterization of adrenergic stimuli on luteinizing hormone (LH) release induced by ovarian steroids in short-term ovariectomized (OVX) rats was studied. Female Sprague-Dawley rats were OVX about 1000 h on the diestrous day 1. After ovariectomy, rats were immediately inserted estradiol-containing Silastic capsules s.c. and implanted atrial Silastic tubing for frequent blood samplings. All the rats received 2 mg of progesterone s.c. at 0930 h the next morning. At 1200 h, the rats received additional treatments: a saline vehicle, prazosin HC1 (an alpha 1-adrenergic antagonist), yohimbine HC1 (an alpha 2-adrenergic antagonist), or propranolol HC1 (a beta-adrenergic antagonist) s.c., respectively. Two different doses of individual adrenergic antagonists were used on an equimolar basis in order to show their effectiveness on steroids-induced LH secretion. Blood samples were collected before and 1, 3, and 5 hours after the treatments through indwelt tubings. LH surge induced by ovarian steroids was suppressed/delayed by prazosin and yohimbine, but potentiated by propranolol in a dose-dependent manner. Results suggested that the hypothalamic alpha 1-, alpha 2-, and beta-adrenoreceptors were involved in the control of LH surge in the short-term OVX-steroids-primed rats. Principally, the alpha 1- and alpha 2-adrenoreceptors played a facilitatory role, and the beta-adrenoreceptors played an inhibitory role in the regulation of LH surge induced by ovarian steroids.

Effects of intraventricular norepinephrine on LH release in short- and long-term ovariectomized steroids-primed rats.

This study examined the noradrenergic mechanism in regulation of luteinizing hormone (LH) release in short- and long-term ovariectomized (OVX) steroids-primed rats. All rats were OVX on the diestrous day 1(D1) morning about 1000 h. After OVX, rats in the short-term OVX group were immediately primed with estradiol (E2, 0.1 mg/kg BW s.c.), fitted with atrial Silastic tubing, and a guide cannula in the right lateral cerebroventricle stereotaxically. Rats in the long-term OVX group received the same treatment (E2, atrial tubing and guide cannula implantation) three weeks later. Rats in both groups received progesterone (2 mg/rat s.c.) at 0930 h on the next day after E2. At 1000 h, intraventricular administration of norepinephrine HCl (NE, 0.01, 0.1, or 1.0 microgram in 2 microliters saline) was given. In short-term OVX-steroids-primed rats, NE did not alter LH levels in the peripheral plasma within 60 or 100 min. By contrast, in long-term OVX-steroids-primed rats, 1.0 microgram of NE gradually decreased plasma LH concentrations, which became significantly different from the initial value at the 60 min time point after treatment. On the other hand, intraventricular injection of 5 ng of the LH-releasing hormone (LHRH) elevated plasma LH concentrations within 10 min in both groups of rats, but at different efficacy: a brief release of LH in short-term OVX-steroids-primed rats and a prolonged release of LH in long-term OVX-steroids-primed rats. These results indicated that the interval after OVX plays a critical role in modulating the responsiveness to NE and LHRH in the steroids-primed OVX rats.

Restoration of sexual behavior in aged male rats by intracerebral grafts of fetal preoptic area neurons.

A decline in sexual arousal and copulatory activity has been observed in male rats with advancing age. Grafting of fetal hypothalamic tissue into the third ventricle of aged male rats restores sexual behavior. This study investigated the effects of grafting fetal preoptic area (POA) neurons into the POA of aged male rats exhibiting decreased sexual behavior. We grafted suspensions of fetal POA neurons into the POA of 20 aged (19 to 24 months old) male rats that displayed no ejaculation. From 2 weeks after grafting, one or more series of male copulatory activity and sexual motivation tests were performed at intervals of 3 to 4 weeks. Three behavioral tests given 5 days apart were repeated for each animal in each series. Among the 20 aged rats with the fetal grafts, 15 showed improved sexual motivation, and 14 of these had copulatory activity restored to levels comparable with those of young males. Among these 14 rats, eight ejaculated during copulation. Copulatory behavior was restored between 21 and 45 days after grafting and persisted until the end of observation (2-4.5 months). Sexual performance did not improve in control aged male rats grafted with either fetal cerebral cortex neurons into the POA or POA, neurons into the ventromedial hypothalamus. The rats that received grafts of fetal POA neurons into the POA and recovered sexual performance also showed improvement or recovery to levels comparable to those in young males of serum testosterone concentrations, serum luteinizing hormone levels after castration, and the post-castration rise in luteinizing hormone. These results indicate that decreases in copulatory activity, sexual motivation, and some neuroendocrine functions in aged male rats are at least partially due to dysfunction of the POA.

Effects of fetal brain grafting on adult behavioral masculinization and defeminization in neonatally androgenized female rats.

Treatment of neonatal female rats with androgen results not only in decreased female sexual behavior but also in enhanced male sexual behavior examined in adulthood. The effects of grafting fetal preoptic area (POA) neurons into the POA, and fetal hypothalamic (HPT) neurons into the ventromedial hypothalamus (VMH), were tested in neonatally androgen-sterilized rats (ASR). The rats were injected subcutaneously with 80 micrograms testosterone propionate within the 24 hours after birth to see if sexual behavior could be normalized by fetal brain grafts. In repeated tests on ASR grafted with fetal HPT into the VMH, the lordotic response was seen to increase to the level seen in non-ASR controls, while the increase in mounting behavior in ASR was suppressed following grafting of fetal POA or cerebral cortex into the POA. These results suggest that there are dysfunctions of POA and VMH in ASR, and that the dysfunctions revealed by sexual behavior can be overcome by fetal POA or HPT grafting.

Age-related changes in the pattern of luteinizing hormone release induced in female rats by male rat urine.

The release of luteinizing hormone (LH) in young (3-4 months) and aged (24-25 months) ovariectomized female Sprague-Dawley rats, s.c. implanted with a 17 beta-estradiol benzoate silastic capsule, was studied in the presence and absence of stimulation by exposure to male rat urine. After taking an initial blood sample at 12:00 (reference sample), either urine, collected from young adult male rats, or distilled water was poured into the female's cage. Blood samples were then collected hourly up to 18:00 via a catheterized jugular cannula. The concentration of LH in the plasma was measured by RIA. The basal plasma LH level in young control rats was found to increase significantly at 16:00 compared with the 12:00 reference sample while no statistically significant change in plasma LH concentration occurred in old controls over the same period. Male rat urine caused a significantly earlier (at 15:00) and prolonged (from 15:00 to 18:00) elevation of plasma LH in young rats compared with young controls. In contrast, exposure of old female rats to male rat urine resulted in no marked change in plasma LH levels. These results suggest that both basal LH release and the response to pheromonal stimulation by male rat urine may be modified with increasing age in female rats.

Effects of monoamine precursors on food intake in male rats.

Effects of monoamine precursors on food intake in male rats were studied. Rats were subjected to an artificial circadian pattern of eating, i.e., a five-hour feeding program during daytime and food deprived during the rest of day. Feeding responses after treatment of drugs were examined. Intraperitoneal injection of L-beta-3, 4-dihydroxyphenylalanine (L-DOPA), DL-threo-dihydroxyphenylserine (DOPS), or 5-hydroxy-L-tryptophan (5-HTP) suppressed food intake. The suppression occurred within the first thirty minutes of the test period and their order of potency came out 5-HTP > L-DOPA = DOPS. The suppressive action of 5-HTP was very strong and lasted at least 3 days. The mechanism of this feeding suppressed action by either the central satiety center or the peripheral inhibiting system was discussed in this context.

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.

Evaluation of the role of noradrenaline precursor on LH release induced by ovarian steroids.

The role of noradrenaline precursor on the release of luteinizing hormone-releasing hormone based on the plasma concentration of luteinizing hormone (LH) was studied in rats. Rats were ovariectomized at 1000h on diestrus day 1(D1) and primed with estradiol immediately after the operation. They received progesterone at 0930h in the next morning (the expected diestrus day 2, D2). Dynamic changes of plasma LH levels were examined in the afternoon of D2. Treatments and results are as follows: 1) Administration of DL-threo-dihydroxyphenylserine (DOPS, 200mg/kg BW, ip) at 0900h on D2, 30 min prior to progesterone treatment, results in 87.5% of rats showing LH surges. 2) Administration of 5-hydroxytryptophan (5-HTP, 100mg/kg BW, ip) 30 min before DOPS completely inhibits the action of DOPS on LH release induced by ovarian steroids. 3) Making a change of the whole working schedule of operation, estrogen was given 5 hours earlier on D1. DOPS and progesterone were given at 0500 hand 0530 h on D2, respectively. It does not induce the LH surge during the whole morning of D2. These results demonstrate that DOPS might just reduce the threshold of the central neurons governing LH release. The time in a fixed lighting schedule was important in determining the LH release induced by ovarian steroids.

Effects of biogenic amine precursors on ovarian steroid-induced LH release in acutely ovariectomized rats.

Effects of catecholamines and indoleamine precursors on the luteinizing hormone (LH) release induced by estradiol (E2) and progesterone (P4) in acutely ovariectomized (Ovx) rats were studied. Rats were Ovx on diestrus day 1 (D1) and received a spaced injection of E2 and P4 on D1 and D2, respectively. One of the following substances: L-beta-3, 4-dihydroxyphenylalanine (L-DOPA), DL-threo-dihydroxyphenylserine (DOPS), or 5-hydroxy-L-tryptophan (5-HTP) was administered intraperitoneally at 0900h on the expected diestrus day 2 (D2). The control group received saline. Serial blood samples were collected in the afternoon of D2 and plasma concentrations of LH were measured by radioimmunoassay. Results indicate that E2 and P4-induced LH release could be facilitated, but not significantly, by DOPS, delayed/inhibited by L-DOPA, and completely inhibited by 5-HTP as compared with saline controls. Exogenous administration of luteinizing hormone releasing hormone (LHRH) induced significantly higher LH release in E2/P4-primed Ovx than in control Ovx rats. Results imply that the classical neurotransmitters in the central nervous system might modify the threshold of LHRH neurons in the hypothalamus.

Effects of electroacupuncture and gonadotropin-releasing hormone treatments on hormonal changes in anoestrous sows.

The therapeutic effects of acupuncture in treating reproductive disturbances of man and animals have been proven in the past and is used clinically already. However, the mechanism of such therapy is not known yet. In this study, anoestrous sows were used to investigate the mechanism. Anoestrous sows with luteal ovaries were allocated to three groups. Four sows received electroacupuncture treatment at Pai-Hui and Wei-Ken (acupuncture treated group; group 1). Three sows received electroacupuncture treatment at Chiang-Feng and Chou-Shu (acupuncture control group; group 2). Four received 50 micrograms of gonadotropin-releasing hormone (GnRH) intravenously (drug control group; group 3). The concentrations of luteinizing hormone, progesterone, oestradiol and cortisol in serum were measured by radioimmunoassay. Oestrus return was monitored during 14 days after treatment. At the end of this observation period, the number of animals returned to oestrus were 3, 1 and 1 in groups 1, 2 and 3, respectively. It suggests that only treatment with acupuncture at Pai-Hui and Wei-Ken had therapeutic effects in inducing oestrus. This finding is further supported by the changes of serum sex hormone concentrations. Serum LH concentrations decreased for about 2 hours after electro-acupuncture treatment both in groups 1 and 2, whereas those in group 3 increased sharply at 10 minutes, reached to a peak at 20 minutes and returned gradually to basal level between 4 and 6 hours after GnRH injection. Serum progesterone concentrations rose between 4 to 6 hours after treatment in groups 1 and 3 but not in group 2. Five sows become oestrus, showed a decreased progesterone level 2 days after treatments whereas the other six anoestrous sows did not. Oestradiol levels did not have meaningful changes during the blood sampling period of 5 to 7 days in these 3 groups. Cortisol levels elevated in 15 minutes after the electroacupuncture in groups 1 and 2. However, the increment of cortisol induced by the electroacupuncture was less than that induced by the first bleeding, indicating that the adrenal stimulation may not be the main reason of the therapeutic action. The results indicated that the electroacupuncture treatment and GnRH injection could alter the release of LH from the pituitary in different ways but only electroacupuncture at Pai-Hui and Wei-Ken has a specific action on ovary and a significant therapeutic effect. Therapeutic effects of electroacupuncture on reproductive disturbance may involve a synergism of somatic-ovary and uterus reflex and central nervous-endocrine system (the hypothalamo-pituitary-ovary axis).

Effectiveness of estradiol and progesterone in inducing LH release in different stages in rat estrous cycles.

The effectiveness of estradiol (E2) and progesterone (P4) in inducing the release of the luteinizing hormone (LH) in the acutely ovariectomized (OVx) rats was studied. Female rats were Ovx in different stages of the estrous cycles and received a series of injections of E2 and P4. LH dynamic changes in the blood were examined in the afternoon of the following day after Ovx. Intact rats treated with oil vehicle or E2 and P4 were used as controls. The surgical operation and oil treatment did not interfere with the normal reproductive rhythm and LH secretion, but treatment with E2 and P4 did facilitate the LH release in some intact rats. E2 and P4 were very effective in inducing LH release in Ovx rats as compared with controls. Results indicated that E2 and P4 are essential substances in eliciting the LH surge, but their efficacies are dependent on the stage in the estrous cycles.

Pattern of reproductive hormone secretion and disappearance rates of LH and FSH in senile male rats.

Old Long-Evans male rats (24-33 months of age) do show postcastration rise in serum LH but do not have postcastration LH rise in the pituitary both as expressed in content and concentration. The serum LH levels of intact and castrated rats of old age show a tendency of decrease, though not to the level of statistical significance. The pituitary FSH content and concentration of intact old rats are not different from those of young adults (3.5-5 months of age), whereas serum FSH level of intact old male rats is significantly higher than that of intact young adults. There is a postcastration rise in the pituitary FSH content as well as concentration and serum FSH level in both age-groups. The half-lives of endogenous and exogenous LH and FSH are not different between old male rats (24- to 31-month-old) and young adults (3- to 5-month-old). Blood testosterone levels begin to decline between the age of 12 and 18 months and remained low from 18 months of age on. These results indicate: (1) deficiencies in the LH regulatory mechanism in response to removal of gonadal steroids are easier to manifest than those of FSH control mechanism in old age in male rats; (2) the ability of clearing circulating LH and FSH of old male rats is not different from that o young adult males, if their molecular sizes are similar, and (3) high serum FSH level of old male rats is not due to prolonged half-life in the circulation.