[Flight and migration : A challenge for medicine in Germany]. / Flucht und Migration : Eine Herausforderung für die Medizin in Deutschland.

In 2015 about 1.1 million refugees came to Germany. As a consequence public health authorities as well as physicians in hospitals and surgeries were faced with considerable challenges and problems. Between January and March 2016 the German Society of Internal Medicine (DGIM) and the Professional Organisation of German Internists (BDI) initiated a survey among their members in order to ascertain which diseases and problems physicians were confronted with. A total of 28,063 members of the DGIM and BDI participated in the survey of which 3626 members answered all questions. This equals a response rate of 11.31 %. Of the respondents, 1865 (51.9 %) stated holding employment positions and 987 (27.4 %) were self-employed. The predominant number of physicians were under the impression that the composition of diseases needing treatment did not change within the time period under survey (55.7 % of employed and 73.7 % of self-employed physicians). Typical disease patterns of internal medicine were mentioned here. Most significant problems when treating migrants and refugees were linguistic communication, cultural affiliation, and psychological traumatic experiences. Little or nothing is known about the modalities of reimbursement for the respective health care areas, especially by physicians in employed positions (84.6 %). In agreement with the vote of the 119th Deutscher Ärztetag, DGIM and BDI recommend the introduction of a nationwide health insurance card for migrants and refugees.

Semiochemicals of the Scarabaeinae VIII. Identification of active constituents of the abdominal sex-attracting secretion of the male dung beetle, Kheper bonellii, using gas chromatography with flame ionization and electroantennographic detection in parallel.

Using gas chromatography with flame ionization detection and electroantennographic detection in parallel (GC-FID/EAD), the active constituents of the sex attractant of male dung beetles of Kheper bonellii were located in the gas chromatogram of an extract of the secretion. These constituents were identified as propanoic acid, butanoic acid, indole, 3-methylindole (skatole) and methyl cis-cascarillate (methyl cis-2-2'-hexylcyclopropylacetate) by, inter alia, GC-MS, (1)H and (13)C NMR analysis, and synthesis. These compounds elicited EAD responses in male as well as female antennae. Racemic methyl cis-cascarillate was synthesized for comparison with the natural methyl ester. Enantioselective GC-FID/EAD using a capillary column coated with OV-1701-OH containing 10% heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin showed that the natural compound co-eluted with the first-eluting enantiomer of the racemic methyl cis-cascarillate, which was the only enantiomer that elicited EAD responses in the antennae of male and female K. bonellii. The absolute configuration of this enantiomer was established by a stereoselective synthesis, which gave methyl (R,R)-cascarillate [methyl (1'R,2'R)-2-2'-hexylcyclopropylacetate] in an enantiomeric excess of 69%.

[The new GOÄ and its pitfalls]. / Die neue GOÄ und ihre Fallstricke.

The German Medical Association is working out a new fee scale for medical invoicing, which has to be reformed because the contents and the ratings are not up to date. The secretary of state for health in Germany demands that the new draft be coordinated with private insurance companies; as a result, they can influence indirectly the relationship between physicians and their patients. The new specifications will narrow the gap between private and social insurance in Germany. We discuss the consequences for the physician-patient relationship and the implications for the political plans to reform the whole insurance system in Germany.

A randomized trial comparing the impact of a nonionic (Iomeprol) versus an ionic (Ioxaglate) low osmolar contrast medium on abrupt vessel closure and ischemic complications after coronary angioplasty.

OBJECTIVES: To assess the effect of nonionic versus ionic contrast media on abrupt vessel closure and major ischemic complications after coronary angioplasty. BACKGROUND: There is a continuous debate about the "thrombogenic potential" of nonionic contrast media. The results of both in vitro and in vivo investigations are incongruent. METHODS: We prospectively evaluated the outcomes of 2,000 patients undergoing percutaneous transluminal coronary angioplasty (PTCA). According to a randomized, double-blind protocol, they received either iomeprol (nonionic; n = 1,001) or ioxaglate (ionic; n = 999). Intracoronary thrombus before PTCA was found more often in the iomeprol group (4.2% vs 2.7%, p = 0.04). No other significant differences between both groups were observed with regard to pre-PTCA clinical and angiographic characteristics. RESULTS: The frequency of reocclusions necessitating repeat angioplasty occurring either in laboratory (2.9% with iomeprol and 3.0% with ioxaglate) or out of laboratory (3.1% vs 4.1%) was not significantly different. The rate of major ischemic complications was also comparable after both contrast media (emergency bypass surgery: 0.8% vs 0.7%, myocardial infarction: 1.8 vs 2.0%, cardiac death during hospital stay: 0.2% vs 0.2%). In the iomeprol group, more patients had dissections post-PTCA (30.2% vs 25.0%, p = 0.01) and more patients received intracoronary stents (31.6% vs 25.7%, p = 0.004). Allergic reactions requiring treatment occurred only in the ioxaglate group (0.0% vs 0.9%, p = 0.002). CONCLUSIONS: The nonionic contrast medium was not associated with a higher rate of abrupt vessel closure requiring repeat angioplasty, or major ischemic events. These data suggest that nonionic contrast media do not increase the risk of thrombotic complications in patients undergoing coronary interventions.

Plasma nitriding monitoring reactor: A model reactor for studying plasma nitriding processes using an active screen.

A laboratory scale plasma nitriding monitoring reactor (PLANIMOR) has been designed to study the basics of active screen plasma nitriding (ASPN) processes. PLANIMOR consists of a tube reactor vessel, made of borosilicate glass, enabling optical emission spectroscopy (OES) and infrared absorption spectroscopy. The linear setup of the electrode system of the reactor has the advantages to apply the diagnostic approaches on each part of the plasma process, separately. Furthermore, possible changes of the electrical field and of the heat generation, as they could appear in down-scaled cylindrical ASPN reactors, are avoided. PLANIMOR has been used for the nitriding of steel samples, achieving similar results as in an industrial scale ASPN reactor. A compact spectrometer using an external cavity quantum cascade laser combined with an optical multi-pass cell has been applied for the detection of molecular reaction products. This allowed the determination of the concentrations of four stable molecular species (CH4, C2H2, HCN, and NH3). With the help of OES, the rotational temperature of the screen plasma could be determined.

Immunoneutralization of neuropeptide Y suppresses luteinizing hormone secretion in rabbits.

In the ovarian intact rabbit, neuropeptide Y (NPY) has stimulatory actions on both LH secretion and GnRH release. The present study measured the pattern of tonic, basal LH release in the rabbit after passive immunoneutralization of endogenous NPY. Eight intact rabbits with third cerebroventricular cannulae and venous catheters were subjected to 8 h of blood sampling at 15-min intervals. Intracerebroventricular (icv) infusion of 1 ml of either normal rabbit serum (NRS) or NPY antiserum (NPY-Ab; raised in rabbits against human NPY) was begun after the second hour of basal blood sampling and was continued for the remaining 6 h of the 8-h protocol. A 1-ml matching iv dose of NRS or NPY-Ab was administered at the start of the icv infusion. All rabbits received both NRS and NPY-Ab treatments 2 weeks apart in a Latin square design. Administration of NPY-Ab significantly (P less than 0.05) suppressed plasma LH after 165 min. After 4 h, plasma LH was maximally reduced to 42% of the control value (pretreatment, 0.093 +/- 0.016 ng/ml; 4 h, 0.039 +/- 0.005 ng/ml). A reduction in the rate of pulsatile LH release also occurred during NPY-Ab treatment (P less than 0.05). Treatment with NRS had no effect on LH. The experiment was repeated in four rabbits 2 weeks after ovariectomy. Administration of NPY-Ab suppressed plasma LH after 75 min in ovariectomized (OVX) rabbits (P less than 0.05). The greatest inhibition was seen after 5 h of NPY-Ab treatment, when LH was reduced to 21% of the control level (pretreatment, 0.841 +/- 0.274 ng/ml; 5 h, 0.134 +/- 0.025 ng/ml). Both LH-pulse amplitude and frequency were suppressed in these OVX does. To determine whether central actions of NPY are of predominant importance in maintaining LH secretion, four OVX rabbits were given NPY-Ab icv only. LH was suppressed after 90 min (P less than 0.05) and was maximally inhibited after 3 h of treatment to 22% of the control value (pretreatment, 1.804 +/- 0.711 ng/ml; 3 h, 0.434 +/- 0.221 ng/ml). Although both LH-pulse amplitude and frequency were diminished, neither was decreased significantly (P greater than 0.05). FSH secretion was not affected by NRS or NPY-Ab treatment in either intact or OVX does. These results clearly indicate that in both intact and OVX does, endogenous NPY is in part responsible for maintaining basal, tonic LH secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Cyclic ovarian function in a male macaque: additional evidence for a lack of sexual differentiation in the physiological mechanisms that regulate the cyclic release of gonadotropins in primates.

Ovarian tissue from adult female rhesus macaques was transplanted into sc abdominal pouches of 4 male rhesus macaques that had been castrated after reaching sexual maturity. The animals were treated daily with cyclosporin A to prevent rejection of the ovarian transplants. Two males in which the transplants were successful showed preovulatory-like gonadotropin surges in response to increasing levels of estradiol. In one of these males (7082), circulating levels of gonadotropins and steroids indicated that cyclic ovarian function had been established. This male showed 5 successive ovarian cycles that averaged 28 days in length. Comparison of the changes in reproductive hormones between 7082 and females with normal menstrual cycles support the hypothesis that the neuroendocrine mechanisms that regulate cyclic release of gonadotropins in primates are not sexually different.

Effects of gonadal steroids on the basal and LRF-induced gonadotropin secretion by cultures of rat pituitary.

The effects of 17beta-estradiol (E2), progesterone (P4), 20alpha-hydroxypregn-4-en-3-one (20alpha-OHP4), and testosterone (T) on the basal and LRF-induced secretion of LH and FSH were studies in monolayer cultures prepared from the pituitaries of adult female rats. Day 4 cultures were used and all steroids were tested at 10-8M concentration for 4 hr. E2 (2.72 ng/ml) alone caused a nonsignificant increase in basal secretion of both LH and FSH; however, the same dose of E2 significantly (p less than 0.001) inhibited the LRF-induced secretion of LH but not of FSH (74% and 88% of 10-8M LRF-treated level, respectively), Testosterone (2.88 ng/ml) alone significantly increased the basal secretion of LH (136% of control level, p less than 0.05) and augmented the effect of LRF on FSH secretion to 130% of the LRF-treated level (p less than 0.05). Contrary to its negative feedback action on the basal secretion of FSH (46% of control level, P less than 0.05), 20ALPHA-OPH4 (3.15 ng/ml) augmented the effect of LRF on LH secretion (130% of LRF-treated level, P less than 0.05). On the other hand, P4 (3.14 ng/ml) did not cause any significant inhibition in the basal and LRF-induced secretion of either LH or FSH. These data indicate that both of the LH- and FSH-LRF; however, their secretory activities are modulated differently by various steroids.

Brain lesions in infant female rhesus monkeys: effects on menarche and first ovulation and on diurnal rhythms of prolactin and cortisol.

Sexual maturation in female rhesus macaques was studied after surgical isolation of the medial basal hypothalamus [complete hypothalamic disconnection (CHD); n = 4] or after creation of amygdaloid lesions (AMYG; n = 6). In four animals, CHD at 8 months did not affect the age when menarche occurred (30 months) but did result in a significant (P less than 0.01) advancement in age at first ovulation (35.8 +/- 1.1 vs. 43.7 +/- 1.1 months for the five controls). Body weights in CHD and AMYG animals were not different from weights of controls at either menarche or first ovulation, but CHD animals gained weight faster than controls. Although there was no overall difference in age at menarche or first ovulation between AMYG animals and controls, the three AMYG animals that sustained damage to the corticomedial amygdaloid area ovulated later than three other AMYG animals without damage to this area. Daily serum levels of LH, FSH, and 17 beta-estradiol were measured in the second ovulatory cycle of each animal and found to be similar among the three groups. Serum progesterone levels revealed that three of the five controls and one of six AMYG animals had short luteal phases typical of pubertal monkeys, whereas all four CHD animals showed luteal phases typical of sexually mature adult animals. Serum cortisol and PRL showed significant diurnal changes in all three groups. These data indicate that in infant rhesus females, intact neural connections to the medial basal hypothalamus are not obligatory for sexual maturation or for the propagation of entrained diurnal rhythms in cortisol and PRL. That isolation of the medial basal hypothalamus resulted in an increase in the rate of weight gain and favored early sexual maturation may indicate that the main effect of the higher brain centers is inhibitory on hypothalamic mechanisms which control these processes.

Interaction of estradiol and LHRH on LH release in rhesus females: evidence for a neural site of action.

The effects on LH release of infusing luteinizing hormone-releasing hormone (LHRH 80 mug/20 min) into the third ventricle, the pituitary, and the peripheral circulation were compared in spayed rhesus monkeys. Within 30 min after iv administration, serum LH concentrations increased to twice to preinfusion levels, and by 120 min declined to original values. Intraventricular or intrapituitary infusions of LHRH resulted in similar LH increments, but the peaks occurred somewhat later (70 to 90 min) and the elevations persisted beyond 200 min. Estradiol-17beta (E2) administered by a sc silastic capsule caused a 5-fold increase in serum E2 within 1 h and reduced serum LH levels by 65% within 4 h. The LH release caused by intrapituitary LHRH was significantly suppressed by maintaining for 72 h E2 concentrations near 100 pg/ml, a level inadequate for stimulating an LH surge. A comparable E2 treatment before intraventricular infusion of LHRH, however, did not inhibit LH release. This difference between the effects of intrapituitary and intraventricular LHRH was demonstrable only in E2-treated monkeys. Moreover, the release of LH after intraventricular infusion of LHRH in E2-treated females was blocked (P less than 0.001) by a single iv injection (90 min before LHRH) of haloperidol (1 mg/kg BW) or phentolamine (5 mg/kg), but was not altered by phenoxybenzamine (3 mg/kg) or propranolol (5 mg/kg). Without E2 pretreatment, LH release after intraventricular LHRH was enhanced by each drug. Phentolamine, injected into both E2- and non-E2-treated monkeys 90 min before an intrapituitary infusion of LHRH had no demonstrable effects on the patterns of serum LH. Our interpretation of these data is that E2 at a concentration below the level that triggers an LH surge has a dual action on LHRH-induced LH release in monkeys: an inhibitory effect exerted directly on the pituitary and a stimulatory effect on the brain. Furthermore, the paradoxical effects of the drugs with and without E2 are due to the involvement of two distinct neuronal systems. The postulated neural effects of both E2 and these drugs can be explained either by an increase in the quantity of injected or secreted LHRH which ultimately binds to LH-secreting cells or by the release of additional endogenous LH-stimulating agents together with ventricular LHRH.

Preovulatory gonadotropin-releasing hormone surge in ovarian-intact rhesus macaques.

The occurrence and profile of the preovulatory hypothalamic GnRH surge in relation to plasma profiles of LH and ovarian steroids, i.e. 17 beta-estradiol (E2) and progesterone (P4), were examined in ovarian intact, freely moving rhesus macaques. Nine monkeys with active ovarian cycles were each fitted with a jugular venous catheter and two push-pull cannulae directed to separate sites within the median eminence (ME). Each female was connected continuously to a tether/swivel device through which daily blood samples or frequent blood samples and ME perfusates (simultaneously at 10- to 20-min intervals for 18-24 h) were obtained without disturbing the animals. An increment in the plasma E2 level (> 150 pg/ml) during the follicular phase (FP) was selected as the preovulatory ovarian signal and served as the index for initiating the ME push-pull perfusion (PPP). Daily increased P4 concentrations of more than 1 ng P4/ml plasma for several consecutive days were consistent with the assumption of ovulation and subsequent formation of a corpus luteum after PPP. A total of 18 PPP trials were completed; each in a fresh ME site. Five of these PPPs were performed during the mid- and late FP (3 were between 6-8 days before and 2 were 4 days before the E2 peak). The remaining 13 PPPs, each of 18- to 24-h duration, were performed between 24 h before and 48 h after the highest daily plasma E2 level, i.e. time zero. Of these 13 PPPs, 2 started within 12 h before (-12 to 0 h), 8 began within 12 h after (0-12 h), and 3 started between 12-24 h after this peak E2 value. During the FP, mean levels of GnRH and LH were less than 2 pg/ml and 20 ng/ml, respectively. During the periovulatory interval (-24 to 48 h around time zero), the release of hypothalamic GnRH (expressed in picograms per ml) increased to 6.63 +/- 2.35 between -12 to 0 h (n = 2), peaked at 20.70 +/- 6.09 between 0-12 h (n = 10), declined to 3.25 +/- 1.39 between 12-24 h (n = 11), and further declined to 0.89 +/- 0.18 between 24-36 h (n = 3). The mean GnRH value from 0-12 h was higher (P < 0.05) than other means (including those during the FP), except for the value between -12 to 0 h. Changes in mean plasma LH values during the same periods paralleled those in GnRH.(ABSTRACT TRUNCATED AT 400 WORDS)

Sexual dimorphism in secretion of hypothalamic gonadotropin-releasing hormone and norepinephrine after coitus in rabbits.

Coital activation of the hypothalamo-hypophyseal ovarian axis (HOA) is well documented in rabbits, but coital excitation of the hypothalamo-hypophyseal testicular axis (HTA) is less well described. We and others have postulated that the response of the HOA to coitus, as characterized by a dramatic release of hypothalamic GnRH, may be mediated by an increase in norepinephrine (NE) neuronal activity. Herein, we studied selective HOA and HTA responses in New Zealand White rabbits before, during, and after coitus. Firstly, we determined the effects of microdialysis (mu D) and blood-sampling methods on plasma LH and testosterone (T) patterns in male rabbits during sexual performance. Subsequently, we compared the patterns of release in GnRH and norepinephrine (NE) from the arcuate nucleus-median eminence (AME) at 10-min intervals with changes in plasma LH levels in copulating male and female rabbits. Lastly, in 2.5-min AME mu D samples from females immediately after coitus, we measured NE and GnRH concentrations to determine whether NE release precedes that of GnRH. Tethered, freely moving rabbits were exposed to their partners for 10 min at the end of the third (10-min sampling for 5-7 h) or second (2.5-min sampling for 4 h) hour. Data from individuals that did not mate during the 10-min of pairing in the 3- to 7-h sampling trials were included as a control group (sham-mated). The results showed no changes (P > 0.05) in plasma LH and T in either mated (LH: pre, 0.13 +/- 0.08 ng/ml; post, 0.15 +/- 0.03 ng/ml; T: pre, 2.39 +/- 1.20 ng/ml; post, 0.85 +/- 0.26 ng/ml) or sham-mated males (LH: pre, 0.21 +/- 0.08; post, 0.25 +/- 0.10 ng/ml; T: pre, 1.46 +/- 0.51 ng/ml; post, 1.40 +/- 0.38 ng/ml). Likewise, coitus did not alter patterns of AME-NE (pre, 0.47 +/- 0.25; post, 0.56 +/- 0.25 ng/ml) and GnRH (pre, 0.61 +/- 0.45; post, 0.74 +/- 0.32 pg/ml) in mated or sham-mated males. The constant HTA activity during coitus in males appears to be independent of experimental manipulation per se because LH and T levels between mu D (0.18 +/- 0.05 and 1.72 +/- 0.85 ng/ml, respectively) and non-mu D (0.16 +/- 0.05 and 1.52 +/- 0.36 ng/ml, respectively) rabbits were not different (P > 0.05). In contrast to males, females displayed unambiguous and simultaneous increases in NE (P < 0.05) and GnRH (P < 0.01) release from the AME within 10-20 min after coitus; these elevated concentrations in mu D samples lasted for 3-4 h. Microdialysis NE levels averaged 0.02 +/- 0.01 ng/ml before mating, whereas postcoital values averaged 0.09 +/- 0.01 ng/ml. GnRH levels were 1.04 +/- 0.56 and 11.78 +/- 5.06 pg/ml before and after coitus, respectively. Concomitant increases in plasma LH levels were also observed after coitus in these female rabbits. Moreover, measurements of NE and GnRH in 2.5-min mu D samples revealed that the postcoital increase in NE preceded that in GnRH by 2.5-7.5 min (P < 0.05). The results suggest that neuroendocrine circuits in the two sexes of the New Zealand White rabbit respond differently to genital stimulation. In male rabbits, coitus does not alter patterns of AME NE or GnRH secretion, nor does it change the circulating levels of plasma LH or T. Conversely, in females, coitus induces the rapid release of hypothalamic NE, GnRH, and pituitary LH. The increase in coitally induced NE occurs before the rise in GnRH, which supports the hypothesis that NE is a critical neurochemical in coital activation of GnRH neurons.

The anterior hypothalamus: how it affects gonadotropin secretion in the rhesus monkey.

The effects of hypothalamic lesions on spontaneous and estrogen-induced LH release were studied in 17 female rhesus monkeys with regular menstrual cycles. In the cycle before surgery, all of the animals experienced 3- to 10-fold increases in serum LH and elevated (above 3 ng/ml) serum concentrations of progesterone. Three to 6 days after the onset of menstruation, lesions were made in the preoptic-anterior hypothalamic area (POA-AHA) in 14 monkeys by radiofrequency thermocoagulation (RF) or by the 180 degrees rotation of a modified "Halász" knife. About 35 days after surgery, the circulating levels of estradiol-17 beta (E2) increased to more than 200 pg/ml in each of the 14 monkeys. Three of the animals with RF lesions and 3 with knife lesions did not release LH or have elevated serum progesterone levels, an indication that they had not ovulated (effective). In 8 animals, 5 with RF and 3 with knife lesions, an LH surge and elevations in serum progesterone were observed (ineffective). After a 90-day postoperative period, the effective and ineffective lesioned groups and an additional group of 6 intact controls were given E2 to test further the ability of the hypothalamic-hypophyseal axis to release LH. The animals with effective lesions did not respond to increased E2 titers (200-400 pg/ml), but those in the ineffective and control groups showed an LH surge. Six to 11 months after surgery, histological examination of the brains from the animals with effective lesions revealed extensive bilateral destruction of the ventral POA-AHA. The suprachiasmatic nuclei or connections between these nuclei and the medial basal hypothalamus (MBH) were destroyed. In 2 animals, the supraoptic and ventromedial nuclei were partially damaged. In no instance was there damage to the paraventricular, dorsomedial, or arcuate nuclei. In animals with ineffective lesions, bilateral destruction of the POA-AHA was less extensive and most of the lesions were unilateral. Ovaries from animals with effective lesions contained small to medium follicles but luteal tissue was conspicuously absent. Spontaneous LH surges and elevated serum P occurred in 2 of 3 additional animals that had 270 degrees cuts around the MBH which left one anterior quadrant intact. Damage to the median eminence region was evident in the one animal that did not ovulate. These results suggest that in rhesus monkeys bilateral destruction of the ventral POA-AHA blocks spontaneous ovulation and compromises the ability of the hypothalamic-hypophyseal axis to release LH in response to estrogen.

Prolactin release following electrical stimulation of the brain in ovarectomized and ovariectomized estrogen-treated rhesus monkeys.

Selected areas in the medial basal (MBH) and rostral (RH) hypothalamus and in the amygdala (AMYG) of long-term ovariectomized rhesus monkeys were electrically stimulated for 30 min through permanently implanted bilateral stainless steel electrodes. Stimulation of an area in the MBH extending from the dorsal part of the ventromedial nucleus through the arcurate nucleus to the upper median eminence resulted in a 200 to 400% increase within 5 min in 8 monkeys. In one monkey the elevated serum prolactin levels persisted after termination of stimulation and in 2 monkeys prolactin remained unchanged during the 30-min stimulation but increased after stimulation was discontinued. Stimulation of the paraventricular-dorsomedial nuclear area in one monkey had no effect on prolactin release. Prolactin responses to stimulation in the RH varied. In 2 monkeys the electrode tips extended into the optic chiasm but part of the uninsulated tips remained in contact with the RH; only one of these monkeys released prolactin in response to stimulation. In 4 monkeys the electrode tips were located in the suprachiasmatic-anterior hypothalamus area. Serum prolactin increased by 200 to 300% in response to stimulation in 2 of these monkeys but increased only slightly in the remaining 2 monkeys. Prolactin responses to stimulation of the AMYG varied with the location of the electrodes. Stimulation in the corticomedial region produced no change in serum prolactin but stimulation in the basal or basolateral area produced marked elevations. An increase in circulating levels of estradiol-17beta (E2) to 100 pg/ml by SC implantation of E2 capsules 72 h before stimulation had no significant effect on basal prolactin levels, but markedly enhanced the prolactin release induced by stimulation in both the MBH and RH. Sham-stimulation did not affect serum prolactin. We conclude that prolactin release in rhesus monkeys can be triggered by electrical stimulation of selected hypothalamic and amygdaloid areas and that stimulation-induced prolactin release in the RH and MBH can be enhanced by E2 pretreatment.

Regulation of the second (estrous) release of follicle-stimulating hormone in hamsters by the medial basal hypothalamus1,2.

In femal proestrous hamsters (1800 h), bilateral electrocoagulative lesions in the arcuate-median eminence (Arc-ME) region blocked the pituitary FSH release that normally would have begun in late proestrus and continued until the afternoon of estrus. This second (estrous) FSH elevation, which is not accompanied by LH release, was unaffected by neural disconnection of the medial preoptic area (MPOA) from the medial basal hypothalamus (MBH) or by production of MBH-pituitary islands. After gonadotropin-releasing hormone was injected into Arc-ME-lesioned hamsters, LH was released. These results suggest that the Arc-ME does not require the MPOA for initiation of the estrous release of FSH.

In vitro gonadotropin-releasing hormone release from hypothalamic tissues of ovariectomized estrogen-treated cynomolgus macaques.

The effects of in vivo 17 beta-estradiol (E2) treatment on in vitro GnRH release and serum LH levels were studied to determine the loci of E2 feedback actions and to examine the hypothalamic mechanisms by which this steroid may regulate LH secretion in monkeys. Ovariectomized cynomolgus macaques received sc Silastic capsule implants containing E2 and were killed 12, 36, 42, or 48 h later. At least one control (CTL) animal received a blank implant and was killed concurrently with each E2-treated monkey. Three untreated animals were used in validation experiments. Before death, each animal was anesthetized with ketamine (15 mg/kg, im), and blood samples were drawn for subsequent LH analysis by Leydig cell bioassay. A diencephalic tissue block was obtained at autopsy and immediately immersed in Krebs-Ringer-phosphate medium (KRP). Mediobasal hypothalamic (MBH) and anterior hypothalamic/preoptic (AH/POA) fragments were quickly dissected from the block and placed in separate superfusion chambers maintained at 37 C. Tissues were superfused at 50 microliter/min with KRP, and 10-min fractions were collected, acidified, and stored at -20 C for subsequent GnRH RIA. Basal immunoreactive GnRH (IR-GnRH) release was measurable from MBH (0.367 +/- 0.063 pg/min) and AH/POA (0.176 +/- 0.065 pg/min) fragments from CTL monkeys. In validation experiments, IR-GnRH release was increased 3- to 7-fold by superfusion with 60 mM K+-KRP only in the presence of Ca+2. Superfusate IR-GnRH coeluted with synthetic GnRH from a Sephadex G-25 chromatographic column, and superfusate and tissue extract GnRH showed appropriate LH-releasing capacities, as determined by rat pituitary cell culture assay. IR-GnRH release rates from MBH or AH/POA tissues varied as a function of in vivo estrogen treatment. GnRH release from both tissues was increased in the E2-treated group killed at 12 h when LH levels were suppressed. Thirty-six hours after E2 treatment, in vitro GnRH release was not significantly different from CTL values. GnRH release rates from MBH and AH/POA tissues obtained 42 h after E2 treatment were significantly greater than CTL release rates (P less than 0.01). This increased in vitro GnRH release at 42 h occurred during the apparent rising phase of the LH surge. Elevated GnRH release was not sustained at 48 h, when surge levels of LH were apparent.(ABSTRACT TRUNCATED AT 400 WORDS)

Existence of multiple forms of follicle-stimulating hormone within the anterior pituitaries of cynomolgus monkeys.

Ovariectomized cynomolgus monkeys were treated with physiological levels of estradiol and progesterone. A reduction in serum levels of FSH was observed after steroid exposure. Anterior pituitary homogenates were prepared from monkeys after 0, 12, 24, or 36 h of exposure to estradiol and progesterone and quantitated for FSH activity by radioreceptor assay (RRA) and RIA. Pituitary FSH activity (expressed as RRA/RIA) increased with duration of exposure to steroids. Forms of FSH within these pituitaries were separated by the column isoelectric focusing technique, chromatofocusing. All pituitary homogenates tested contained FSH isohormones that eluted at similar isoelectric points. Each FSH isohormone exhibited a mol wt similar to that of a purified FSH standard, but differed in ability to displace labeled FSH from a biological receptor preparation. FSH forms with basic isoelectric points exhibited greater RRA/RIA values than forms with more acidic isoelectric points. The relative proportion of the more basic FSH forms increased within pituitary tissue with duration of exposure to steroids. All FSH forms were secreted by pituitary cells in culture. The biochemical basis for the microheterogeneity appears to be the degree of sialic acid incorporation into the FSH molecule. The results of these studies demonstrate that the cynomolgus monkey pituitary responds to the surrounding hormonal milieu by altering the relative proportions of FSH forms present within that gland.

Cryptorchid rhesus macaques: long term studies on changes in gonadotropins and gonadal steroids.

We studied the relationship of testosterone (T), dihydrotestosterone (DHT), and 27 beta-estradiol (E2) to FSH and LH in the systemic circulation of six rhesus macaques with surgically induced cryptorchidism at selected times over 420 days. We measured these hormones by RIA and compared their concentrations with those of four sham-operated controls. Midway through the experimental procedure the animals were electroejaculated, and on day 425 the testes were removed and analyzed histologically. The cryptorchid monkeys did not have sperm in their ejaculates, and treatment adversely affected spermatogenesis. For the first 30 days after treatment none of the hormones differed significantly between cryptorchid monkeys and controls. Gonadotropins in three castrated males, however, gradually rose to postcastration levels within approximately 2 weeks post operation. After castration, all three steroids declined significantly within 24 h. Beginning on days 60, 150, 215, 320, and 420 post operation the animals were bled for 5 days on a diurnal regimen. The steroids as well as LH concentrations varied diurnally. The concentration of FSH never showed diurnal variation in any of the groups at any of the periods studied. Concentrations of T and LH did not differ significantly between control and cryptorchid groups at any time. With longer time periods (beginning 215 days after cryptorchidism had been induced), DHT in cryptorchid monkeys was significantly higher than in controls (P < 0.01). Although E2 was significantly lower in cryptorchid monkeys on days 60 and 150 post operation, this difference disappeared with time. Changes in steroid concentrations were not associated with the elevations in FSH that occurred in cryptorchid monkeys by days 60 and 420. Therefore, we assumed that they were independent phenomena. Significant FSH elevations in cryptorchid monkeys occurred only in the fall of the year. Testicular homogenates from cryptorchid and control monkeys produced similar quantities of T, DHT, and androstenedione in vitro. Very little E2 or estrone was found. Although significant amounts of progesterone were quantified in the incubation media of control testes, little or no progesterone was found in media from cryptorchid testes. Similar results were obtained when these steroids were measured in plasma collected from the testicular veins. In testicular venous plasma, 20 alpha-dihydroprogesterone concentrations were not elevated after cryptorchidism. These data suggest that there is similar negative feedback control of gonadotropins in crytorchid and control rhesus monkeys. The absence of dramatic differences in systemic concentrations of FSH between the two groups suggests that the seminiferous tubule does not play a major role in the negative feedback control of gonadotropins in this species or that the tubular component of this control system is not perturbed by the cryptorchid condition...

Pulsatile secretion of luteinizing hormone during the menstrual cycle of rhesus macaques.

The secretion of LH, PRL, and cortisol was investigated in 4 sexually mature female rhesus macaques with cardiac catheters protected by tethers. Based on endocrine parameters, all 4 of the animals ovulated within 2 months from the time they were tethered, and regular menstrual cycles of 24-34 days were observed. The catheters remained patent for 6-12 months without reposition or repair. Plasma levels of 2 stress-labile hormones, PRL and cortisol, showed diurnal fluctuations comparable to those observed in untethered animals. The frequency of LH secretory episodes was determined by measuring bioactive LH in blood samples collected at 10-min intervals in the follicular phase and at 15-min intervals in the luteal phase of the menstrual cycle. In 10 trials during the follicular phase, we estimated that an average of between 14 and 15 LH pulses occurred every 12 h. The interpulse interval ranged between 20-80 min and averaged 50 min. No change in pulse frequency was observed across the follicular phase. The number of LH pulses decreased after ovulation, and by the end of the luteal phase, the interpulse interval was 4-6 h. One example during the preovulatory LH surge revealed the high frequency, high amplitude nature of LH secretion at that time. Our experience indicates that tethered animals with cardiac catheters show no hormonal indications of stress and represent the best available model for studies requiring frequent and prolonged access to the vascular system. Our data suggest that peripheral LH fluctuations in rhesus monkeys, as in other mammals, are pulsatile, and the frequency of these pulsatile episodes changes with different phases of the menstrual cycle, presumedly in response to varying stimuli to the pituitary from the brain.