Serum progesterone and estrogens in elephants.

Serum progesterone and estrogens were measured by radioimmunoassay in the serum of immature, mature, and pregnant African and Asian elephants. Progesterone was elevated from 26 to 215 pg/ml in nonpregnant animals and up to 480 pg/ml in late pregnancy animals. No relationship to reproductive state was evident for the low levels of estrogens which ranged from 9 to 37 pg/ml.

The effect of pinealectomy on seasonal changes in prolactin secretion in the white-tailed deer (Odocoileus virginianus borealis).

Surgery was performed on four buck and four doe 9-month-old white-tailed deer in March of 1978. Pinealectomy was performed on two deer of each sex, and the remaining animals received sham operations. At monthly intervals over the following year, baseline and TRH-stimulated (200 microgram/deer, iv bolus) serum PRL was measured over a 3-h period by RIA. Baseline PRL levels in sham-operated animals followed a circannual pattern, with peak levels occurring in June (74-237 ng/ml for does; 34-193 ng/ml for bucks) and lowest levels occurring in midwinter (0.41-0.44 ng/ml for does; 0.10-0.13 ng/ml for bucks). Pituitary responsivity to TRH followed the same patterns as that seen for basal PRL levels in sham-operated deer, with the highest peak serum PRL responses in June (198-568 ng/ml for does; 190-395 ng/ml for bucks) and the lowest peaks seen in midwinter (0.27-0.80 ng/ml for dose; 0.29-2.62 ng/ml for bucks). Pinealectomy appeared to abolish the circannual basal serum PRL rhythms in bucks, while this rhythm was maintained in does. Basal PRL levels in pinealectomized bucks ranged from 0.36-10.5 ng/ml, and basal levels in pinealectomized does ranged from 0.10-29.4 ng/ml. The greatest peak PRL response to TRH in pinealectomized deer was seen in August (41.2-93.4 ng/ml for does; 32.0-40.5 ng/ml for bucks), while the lowest peak response occurred in January (0.33-11.0 ng/ml for does; 0.50-17.0 ng/ml for bucks). Both sexes retained a degree of seasonality in their pituitary responsiveness to TRH, but the magnitude of the response in pinealectomized deer was greatly diminished in the summer months and increased in the winter months. Our results show that pinealectomy alters the naturally occurring photoperiod-linked seasonal profile of serum PRL in white-tailed deer and the associated pituitary responsiveness to TRH.

Anti-estrogens and plasma proteins. II. Contraceptive drugs and gestagens.

PIP: The effects of Ovral (.5 mg norgestrel and .05 mg ethinyl estradiol (EE), and Norlestrin (1 mg norethindrone acetate and .05 mg EE) in women; dydrogesterone alone and with EE in men; and norgestrel, chlormadinone, EE, cyproterone and 17-alpha-methyltestosterone in green monkeys, on plasma proteins and hormones were studied, in an attempt to reverse estrogenic changes. Both contraceptives, given for 2 cycles to 25 women, increased corticosteroid-binding globulin, cortisol, thyroxin, and plasminogen, and Norlestrin increased fibrinogen. 30 or 40 mg dydrogesterone with .01 mg EE did not block the changes induced by estrogen alone in 5 men. Plasma protein and hormone levels in monkeys, tabulated after 2.5 mcg EE, 2 mg norgestrel alone and with 2.5 mcg EE showed that the estrogen effects of EE on corticosteroid-binding globulin and haptoglobin could be reversed by norgestrel. Similarly, 12.5 mg chlormadinone blocked the action of EE on thyroxine. The experiment with cyproterone acetate and methyltestosterone did not yield significant results.^ieng

Early effects of pinealectomy on LH and testosterone secretion in white-tailed deer.

The early effects of pinealectomy on LH and testosterone secretion were studied in 11 white-tailed bucks. Six bucks were pinealectomized and three were sham-operated in early march at 9 months of age. Two unoperated bucks of the same age were also followed. The response of the pituitary gland and testis to LH releasing hormone (LHRH) was monitored for 2h each month for 1 year by radioimmunoassay of serum LH and testosterone. Prestimulation levels of LH (expressed as microgram NIH-oLH-S7) exhibited a cosinor curve pattern over the year (P less than 0.002) with levels ranging between 0.1 and 3.9 micrograms/l. Highest levels in pinealectomized males occurred in May 2 months after surgery and in control (sham-operated and unoperated) males in August. Maximal LH response to LHRH was characterized by a double-peaked curve in serum LH with the early peak around 20 min and a later peak at about 2h after injection. Maximal response to LHRH occurred in May in pinealectomized bucks and in August in control bucks. Baseline testosterone concentrations and testosterone response to LHRH varied in a seasonal fashion throughout the 12-month period in control bucks (P less than 0.001) but not in pinealectomized bucks. Baseline testosterone concentration and testosterone response to LHRH rose within 2 months after surgery in pinealectomized bucks and remained relatively constant for the next 10 months. These data demonstrate an early effect of pinealectomy on LH and testosterone secretion in 9-month-old animals kept under conditions of natural photoperiod and suggest differences in the response to pinealectomy by the pituitary gland and testes.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of body fat distribution with plasma lipids, lipoproteins, apolipoproteins AI and B in postmenopausal women.

Associations between the distribution of body fat, measured by the waist/hip circumference ratio (WHR), and plasma lipid fractions were examined in 84 postmenopausal women. WHR was correlated r = 0.39 with body mass index (BMI). After adjustment for BMI and other covariates, WHR was positively and significantly associated with concentrations of triglycerides, apolipoprotein B, low-density lipoprotein cholesterol, and the total cholesterol/high density lipoprotein cholesterol ratio. WHR was negatively and significantly associated with concentrations of high density lipoprotein cholesterol and apolipoprotein AI. These results indicate that in postmenopausal women abdominal fat preponderance is associated with an atherogenic plasma lipid profile, independent of its association with BMI.

The effect of peripheral administration of peptides on food intake, glucose and insulin in wolf pups.

In the studies reported here we demonstrate that bombesin decreases food intake in wolf (Canis lupus) pups without altering glucose or insulin levels. A high dose of cholecystokinin-octapeptide (CCK, 5 micrograms/kg) decreased food intake. CCK produced a transient increase in insulin, without altering glucose. Glucagon (0.5 mg/kg) failed to decrease food intake despite producing a marked hyperglycemia and hyperinsulinemia. Calcitonin was ineffective at decreasing food intake, although it did decrease the time spent feeding. These studies suggest a potential role for peripheral peptides in food regulation in the wolf.

Naloxone induced suppression of feeding in tigers.

Naloxone suppresses, but does not eliminate feeding in Siberian tigers. Naloxone administration paired with novel foods appeared to induce emesis.

Effects of opiate antagonists on feeding and spontaneous locomotion in deer.

The effects of opioid antagonists on seasonal changes in feeding behavior of white-tailed deer (Odocoileus virginianus) during fall, winter, and summer, as well as in bottle-fed fawns are described. Naltrexone had no effect on the amount of milk ingested by bottle-fed fawns. After weaning naltrexone significantly decreased feeding in both the summer and winter, with no difference in the effect for either season, indicating that opioids do not play a role in the winter hypophagia or the summer hyperphagia in deer. Similarly there was no seasonal effect on the ability of naloxone to decrease feeding in yearlings during summer, fall, and winter. Naltrexone significantly decreased spontaneous locomotion in the fawns in winter and the fall. In yearlings there was a tendency for the high dose of naloxone to decrease spontaneous locomotion in winter whereas in summer and fall it tended to enhance time spent moving. These data suggest that the endogenous opioid control of feeding in deer is independent of the seasonal effect on feeding and endogenous opioids do not play a role in the seasonal rhythmicity of feeding in deer. The effects of endogenous opioids on spontaneous locomotion do appear to be linked to changes in seasonal activity patterns.

Effects of manipulations of glucoregulation on feeding in the ground squirrel.

Insulin and 2-deoxy-D-glucose (2-DG) stimulate feeding in rats, while glucagon inhibits feeding. We report here their effects on food intake in the 13-lined ground squirrel (Spermophilus tridecumlinectus). These hibernating animals are an interesting model for studying appetite regulation because of the marked seasonal variations in food consumption. Food intake reached a peak of 286 +/- 7 g/kg/day in mid July, decreasing to 16.1 +/- 3 g/kg/day in September. Studies during the hyperphagic period showed that glucagon (0.5 to 1 mg/kg) decreased feeding 30 minutes post injection (p less than 0.01) whereas at 4 hours glucagon produced a 37% increase in feeding (p less than 0.05). During the hypophagic period, glucagon failed to alter food consumption. Insulin (5-100 Units/kg) produced no effect on feeding in hyperphagic animals despite a decrease in glucose from 193 +/- 10 mg/dl to 55 +/- 4 mg/dl after 100 Units/kg. However, insulin (50 and 100 Units/kg) resulted in significant increases in food consumption at 2 and 4 hours (p less than 0.01 and 0.05, respectively) when administered while the animals were hypophagic. 2-DG (250-750 mg/kg) increased food consumption (hyperphagic phase) by 76% at 20 hours (p less than 0.01) with significant increases being present as early as 4 hours, although when 2-DG was given to hypophagic animals it resulted in decreased food intake at 4 hours (p less than 0.05). We conclude that the effects of glucoregulatory manipulations on food consumption are markedly influenced by the circannual rhythm of feeding in the 13-lined ground squirrel.

Opioid modulation of ingestive behaviors in woodchucks and racoons.

We have examined the effect on feeding of opioid blockade with naloxone in two species which demonstrate a marked seasonality in their feeding patterns, the racoon (Procyon lotor) and the woodchuck (Marmota monax). Naloxone suppressed food intake in the woodchuck which is a true hibernator. Naloxone failed to suppress food intake in the racoon and, in fact, enhanced intake of a preferred sucrose solution. In the racoon, ir-dynorphine concentrations were extremely high in the hypothalamus compared to the values obtained in rats and woodchucks. We suggest that possible explanations for the lack of responsiveness to opiates in racoons may be their extremely high daily food intake relatively to body mass when compared to woodchucks and rats and the high levels of ir-dynorphin may be sufficient to overcome the inhibitory effect of naloxone. These studies stress the occurrence of species diversity in the response to opioid antagonism.

The effect of naloxone on feeding and spontaneous locomotion in the wolf.

The effect of naloxone on food intake and activity levels was studied in the wolf (Canis lupus). Naloxone decreased food intake at both the 1 mg/kg and 5 mg/kg dose. There was no quantitative difference in the magnitude of the decrease in food intake produced by naloxone in winter or summer. Wolves ate significantly greater amounts of deer meat than dog chow after naloxone when expressed on a mass basis but there was no difference when the amounts of food ingested were expressed in calories. This suggests a role for endogenous opiates in the regulation of energy intake. The putative satiety factor, cholecystokinin-octapeptide, had no effect on food intake in wolves. Naloxone decreased spontaneous locomotion and increased time spent resting in wolves. The effects of naloxone on activity were significantly more marked in winter compared to summer.

Diazepam-induced feeding in captive gray wolves (Canis lupus).

Diazepam doses of 0.2, 0.4, and 0.8 mg/kg induced feeding in sated gray wolves in a dose-dependent manner (p less than 0.001). Neither 0.8 mg/kg of the benzodiazepine antagonist, beta-CCP (p = 0.36), nor 0.8 mg/kg of the benzodiazepine inverse agonist, beta-CCE (p = 0.85), decreased the diazepam-induced hyperphagia. Five of 6 naive wolves (p = 0.003) ate dry dog food within 15.4 +/- 1.9 min of being given 0.4 mg/kg diazepam and freely chose dog food after the single diazepam administration.

Blood volume measurements in gopher snakes, using autologous 51Cr-labeled red blood cells.

Blood volume determinations were performed in 5 anesthetized gopher snakes (Pituophis melanoleucus catenifer) by means of a 51Cr-labeled red blood cell (RBC) method. The mean blood volume was 52.8 ml/kg of body weight (+/- 6.21 SE). Previous blood volume measurements have not been reported for this species. The RBC survival rate was estimated to be greater than 660 days. The RBC survival rate is long, but it cannot be determined accurately by this method.

A technique for pinealectomy in deer, with notes on the neuroanatomy.

A technique for removing the pineal gland in adult and young male deer is described. A unilateral craniotomy or craniectomy was performed and the pineal gland was approached by parting the 2 hemispheres of the brain. The blood vessels supplying the pineal gland were coagulated and the gland was removed with forceps. Magnification, microtechniques, fiberoptic illumination, and bipolar coagulation rendered the surgical procedure safe and precise.

Immobilization of gray wolves (Canis lupus) with sufentanil citrate.

Gray wolves (Canis lupus) were immobilized with 0.5 mg/kg xylazine plus 7.5 micrograms/kg of either sufentanil (n = 8), etorphine (n = 8), or carfentanil (n = 2). Drug doses used in this study were selected to provide consistency for comparison and are not recommended doses for effective immobilization of wolves. Induction times were similar among groups (11.9 +/- 1.0 min). Thirty min after induction, wolves were given either 0.5 mg/kg naloxone hydrochloride plus 0.15 mg/kg yohimbine hydrochloride or saline only intravenously. Arousal times for wolves given naloxone and yohimbine (1.2 +/- 0.1 min) were shorter than wolves given saline (35.5 +/- 6.4 min). Respiratory rates were similar among the three drug groups (6.9 +/- 1.0 breaths/min). One animal given sufentanil then saline was found dead 108 min after induction. Presumptive diagnosis was renarcotization and hypothermia. Results indicated that sufentanil is an effective opioid immobilizing agent for gray wolves.

Fertility control in female white-tailed deer.

Silastic rods containing either melengestrol acetate (MGA) or levonorgestrel (LN) were placed in anestrous white-tailed deer (Odocoileus virginianus borealis) does to evaluate the contraceptive efficacy of the implants over a 2 yr period. Implants of MGA were placed in five does during mid-pregnancy to evaluate the effect of this treatment on pregnancy, parturition and lactation. Pregnancies were not observed in the five animals implanted with MGA during anestrus. Three of five does implanted with LN became pregnant in the first season. Pregnancy was not interrupted in the five pregnant does implanted with MGA and it was necessary to remove the implants and treat the does with an estrogen to achieve parturition. One of five fawns was delivered alive and was raised by the doe. MGA was effective for 2 yr as a contraceptive in white-tailed deer, LN was ineffective as used, and MGA placed in pregnant does delayed or prevented normal parturition and thus should not be used in pregnant deer.

Immobilization of free-ranging African lions (Panthera leo) with a combination of xylazine hydrochloride and ketamine hydrochloride.

The combination of 55 mg/ml xylazine hydrochloride and 200 mg/ml ketamine hydrochloride was effective for immobilizing African lions in Tanzania. Nineteen adult females were given between 55 and 110 mg xylazine hydrochloride in the first dart. Initial doses of 110 mg xylazine hydrochloride and 450 mg ketamine hydrochloride equivalent to greater than 0.9 mg/kg xylazine hydrochloride were most effective in achieving rapid immobilization. Lower doses of xylazine hydrochloride required supplementation with ketamine hydrochloride. These doses could be delivered easily in 3-ml darts. The use of lightweight darts and a blowgun was found to be useful as a supplement to longer range dart projector systems since many animals could be approached at short range.

Gray wolf density and its association with weights and hematology of pups from 1970 to 1988.

We examined weights and hematologic profiles of gray wolf (Canis lupus) pups and the associated wolf density in the east-central Superior National Forest of northeastern Minnesota (USA) during 1970 to 1988. We collected weight and hematologic data from 117 pups (57 females, 60 males) during 1 September to 22 November each year. The wolf density (wolves/800 km2) trend was divided into three phases: high (72 +/- 7), 1970 to 1975; medium (44 +/- 2), 1976 to 1983; and low (27 +/- 2), 1984 to 1988. Wolf numbers declined (P = 0.0001) 39 and 63% from 1970 to 1975 to 1976 to 1983 and from 1970 to 1975 to 1984 to 1988, respectively. Weight was similar between male and female pups and did not vary as wolf density changed. Mean hemoglobin (P = 0.04), red (P = 0.0001) and white blood cells (P = 0.002), mean corpuscular volume, mean corpuscular hemoglobin concentration and mean corpuscular hemoglobin (P = 0.0001) did differ among the multi-annual phases of changing wolf density. Weight and hematologic data also were compared to values from captive wolf pups. The high, but declining wolf density was associated with macrocytic, normochromic anemia in wolf pups, whereas the lowest density coincided with a hypochromic anemia. Although hematologic values show promise for assessing wolf pup condition and wolf population status, they must be used cautiously until data are available from other populations.

Immobilization of white-tailed deer by etorphine and xylazine and its antagonism by nalmefene and yohimbine.

White-tailed deer (Odocoileus virginianus) were immobilized with either 4.0 mg etorphine hydrochloride (ETOR) or 3.5 mg ETOR and 50.0 mg xylazine (XYL). Deer immobilized with ETOR only were given 4.0 mg nalmefene hydrochloride (NAL), a new opioid antagonist, 20 min after induction. Deer immobilized with ETOR and XYL received 3.5 mg NAL and 0.125 mg/kg yohimbine hydrochloride (YOH). The dose of 4.0 mg ETOR did not provide acceptable immobilization and was discontinued. A NAL:ETOR ratio of 1:1 was insufficient for complete and sustained antagonism of ETOR. Subsequently, deer were immobilized with ETOR and XYL as before which was then antagonized with 35.0 mg NAL and 0.125 mg/kg YOH. The 10:1 ratio of NAL:ETOR appeared to provide complete antagonism with no evidence of renarcotization. Although more study is required, NAL could become a useful antagonist for opioid-induced immobilizations.