S A Wager-Srdar

Minneapolis Veterans Affairs Hospital, Minneapolis, Minnesota, United States

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Publications (9)26.52 Total impact

  • S A Wager-Srdar, A S Levine
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    ABSTRACT: Rats are less sensitive to the satiating effect of CCK-8 during some reproductive states such as estrus and proestrus, and in ovariectomized rats following the administration of estradiol and progesterone. The sensitivity of rats to CCK-8's effect on food intake decreases as lactation progresses. During lactation, prolactin and progesterone levels are elevated. Implantation of ectopic pituitaries increases prolactin levels in males and females as well as progesterone levels in females. To evaluate whether or not prolactin elevation modifies CCK's effect on feeding, we studied the effect of CCK-8 on food intake during the early dark cycle in male and female rats implanted with ectopic pituitaries. As previously demonstrated, prolactin levels were elevated in both male and female pituitary-implanted rats and progesterone levels were elevated in the female rats. CCK-8 inhibited food intake in sham-operated male rats, but did not reliably decrease early dark cycle food intake in sham-operated or pituitary-implanted female rats or pituitary-implanted male rats. Thus an elevation in prolactin levels does not appear to modify the effect of CCK-8 on food intake in female rats. We also evaluated the effect of CCK on consummatory and maternal behavior in lactating rats. CCK-8 altered the meal patterns of lactating rats primarily by decreasing the rate of food consumption and increasing the latency to the first meal. The latency to the first meal of rats receiving CCK was increased during early and mid-lactation and the PW period, but not during late lactation compared to that of the saline-injected rats. CCK-8 did not modulate any of the maternal behaviors studied.(ABSTRACT TRUNCATED AT 250 WORDS)
    Physiology & Behavior 09/1991; 50(2):331-6. · 3.16 Impact Factor
  • S A Wager-Srdar, A S Levine
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    ABSTRACT: Cholecystokinin octapeptide (CCK-8) and glucagon (GLG) decrease food intake of a number of species. However, the responsiveness of rats to the food intake effects of these peptides may develop differentially due to sex, age and/or developmental state. Male and female weanling rats decreased early dark cycle food intake following the administration of 5 and 10 micrograms/kg CCK-8 and male rats were more responsive than female rats, p less than 0.05. GLG did not decrease early dark cycle food intake of either male or female weanling rats. Weanling male rats increased plasma glucose and insulin levels in response to GLG administration, p less than 0.05. Male rats were retested with GLG (250 and 500 micrograms/kg) at 6, 9 and 22 weeks of age. GLG did not decrease food intake of these rats until they reached 9 weeks of age and they were still responsive at 22 weeks of age, p less than 0.05.
    Physiology & Behavior 05/1989; 45(4):747-51. · 3.16 Impact Factor
  • S A Wager-Srdar, M Gannon, A S Levine
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    ABSTRACT: Cholecystokinin (CCK) suppresses food intake in a number of animal models, but appears to be less effective in females [5,23]. We studied the effect of CCK on food intake in female rats on each day of the estrous cycle. In addition, we evaluated the effect of sex hormones on food intake in intact and castrate male rats which had been injected daily with oil or testosterone propionate + oil and ovariectomized female rats injected daily with oil, estradiol, progesterone or estradiol + progesterone. Food intake in intact, castrate and castrate + testosterone replaced male rats was decreased by CCK (5, 10 and 20 micrograms/kg) IP (p less than 0.05). Food intake was decreased by CCK (20 micrograms/kg) only during diestrous and metestrus in cycling female rats. During metestrus, a period of low estradiol in the presence of progesterone, food intake was also suppressed by CCK (5 and 10 micrograms/kg). CCK failed to decrease food intake in ovariectomized females receiving oil, estradiol and estradiol + progesterone. However, animals receiving progesterone alone responded to the high dose of CCK (20 micrograms/kg). Our data suggest that the effect of CCK on food intake in female rats may be dependent on the presence of progesterone. The lack of sensitivity to CCK during proestrus and estrus suggests that estradiol may be modulating the "permissive" action of progesterone on CCK's satiety effect.
    Physiology & Behavior 02/1987; 40(1):25-8. · 3.16 Impact Factor
  • S A Wager-Srdar, M Gannon, A S Levine
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    ABSTRACT: Previous studies have shown that estradiol and progesterone can alter the response of female rats to naloxone. For example, ovariectomized rats receiving estradiol were found to be less sensitive to the anorexic effect of naloxone than ovariectomized rats receiving oil (vehicle) or progesterone. In the present paper, we evaluated the effect of naloxone on nocturnal food intake in female rats during each stage of the estrous cycle to determine whether changing levels of gonadal hormones in intact female rats would affect their response to naloxone. To evaluate the role testosterone might play in modulating the male rat's feeding response to naloxone we studied the effect of peripherally administered naloxone (0.1, 1.0 and 10 mg/kg) on nocturnal food intake of intact, castrate and castrate + testosterone propionate male rats. During late metestrus, diestrus and proestrus, female rats decreased nocturnal food intake following the administration of naloxone (1.0 and 10 mg/kg) SC (p less than 0.05). During estrus, female rats failed to decrease food intake following any of the doses of naloxone administered. The male rat's response to naloxone does not appear to be altered by the presence or absence of testosterone. Thus, the level of estradiol and progesterone at different stages of the estrous cycle may affect the female rat's response to the satiety effect of naloxone.
    Physiology & Behavior 02/1987; 39(5):669-72. · 3.16 Impact Factor
  • S A Wager-Srdar, J E Morley, A S Levine
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    ABSTRACT: During lactation food intake increases greatly without an accompanying large increase in body weight; therefore, this physiological state is an excellent example of non-obese hyperphagia. In the present study, we found that cholecystokinin (CCK-8) decreased food intake in lactating and virgin female rats. However, female rats were more resistant to the effect of CCK on eating following weaning of the pups. Bombesin (BB) suppressed food intake in virgin female rats and in lactating rats during early and mid lactation. Rats were resistant to its satiating effect during late lactation and during the postweaning period. Calcitonin potently suppressed food intake in virgin, lactating and postweaning rats. The present findings suggest that CCK and bombesin decrease food intake more effectively in virgin female rats and during earlier phases of lactation than during late lactation or postweaning.
    Peptides 01/1986; 7(5):729-34. · 2.52 Impact Factor
  • S A Wager-Srdar, B A Gosnell, J E Morley, A S Levine
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    ABSTRACT: Lactation provides an excellent model of non-obese hyperphagia. There is accumulating evidence that endogenous opioids play a role in the modulation of the hormonal changes that occur during lactation. Because endogenous opioids appear also to play a role in the regulation of feeding, we studied the effects of the opiate agonist, butorphanol tartrate, and an opiate antagonist, naloxone, on food intake in virgin female rats and in rats during early, mid and late lactation and during post-weaning. It has been reported that female rats are less sensitive to the suppressant effects of nalmefene, an opioid antagonist, than male rats. Therefore, we also examined the effect of naloxone, an opioid antagonist, on spontaneous nocturnal feeding and 24 hour food deprivation-induced food intake in virgin female rats. We found that female rats were relatively insensitive to the food suppressant effects of naloxone following 24 hour food deprivation, while male rats tested under similar conditions had a decreased intake in response to naloxone. Despite the marked hyperphagia that occurred during lactation, there were minimal alterations in the response to opiate agonists and antagonists during this time period. Our data suggest that endogenous opioids may not play a pivotal role in the hyperphagia of lactation.
    Pharmacology Biochemistry and Behavior 10/1985; 23(3):345-8. · 2.82 Impact Factor
  • S Wager-Srdar, A S Levine, J E Morley
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    ABSTRACT: The exogenous opioids butorphanol tartrate (BT) and ethylketocyclazocine (EKC) have been reported to stimulate feeding in rats. In this study we evaluated the effects of purines (known to suppress feeding) and the adenosine antagonist, caffeine, on opioid induced feeding. Adenosine and inosine significantly suppressed BT and EKC induced feeding at various doses and time points. Caffeine enhanced food consumption was suppressed by various doses of naloxone, but was not suppressed by adenosine or inosine. Although caffeine itself induced further feeding, it did not enhance BT induced food consumption. Adenosine and inosine failed to suppress BT induced feeding when 12.5 mg/kg of caffeine was administered to the rats suggesting blockade of the adenosine receptor by caffeine. In contrast to 12.5 mg/kg caffeine, high dose caffeine (50 mg/kg) suppressed BT induced feeding over a 4 hour time period. Adenosine (50 mg/kg) and inosine (50 mg/kg) injected one hour after injection of BT and caffeine (50 mg/kg) reversed the suppressive effect of high dose caffeine in BT induced feeding. These studies indicate that opioid induced feeding can be suppressed by adenosine and inosine. Also, caffeine can reverse the suppressive effect of adenosine and inosine on feeding and vice versa. Naloxone's suppression of caffeine enhanced food consumption indicate that at least part of caffeine's effect on food intake may be mediated through an opioid mechanism.
    Pharmacology Biochemistry and Behavior 08/1984; 21(1):33-8. · 2.82 Impact Factor
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    ABSTRACT: Much evidence has accumulated indicating that cigarette smokers weigh less than non-smokers and that smokers gain weight when they cease smoking. In the present study we evaluated the effects of cigarette smoke and nicotine on food intake, weight gain, resting energy output, brown fat mass and opiate binding (opiates initiate feeding in sated rats) in rats. Chronic smoke exposure slightly suppressed growth rate and food intake after 14 days of smoke exposure. Blood glucose levels and intrascapular brown adipose mase were increased as a result of smoke exposure. Hamsters chronically exposed to cigarette smoke decreased body weight; however, food intake was not significantly suppressed. Short term (5 day) exposure to nicotine (4 and 2 mg/kg/day) suppressed growth rate and food intake. Nicotine (4 and 2 mg/kg) significantly suppressed water ingestion in water-deprived rats and altered the quantities of flavored solutions ingested by rats compared with those ingested by rats receiving no nicotine. Thus cigarette smoke and nicotine exposure affects food intake, energy utilization and taste perception; all parameters which contribute to overall body mass; however, these parameters change in a complex manner with only small changes occurring at specific time intervals.
    Physiology & Behavior 04/1984; 32(3):389-95. · 3.16 Impact Factor
  • S A Wager-Srdar, M M Oken, J E Morley, A S Levine
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    ABSTRACT: Purines are putative neurotransmitters which appear to be involved in regulating several vegetative functions. We examined the effect of purines and their antagonist, caffeine, on colonic temperature of rats. Adenosine injected ip lowered colonic temperature in a dose responsive manner at ambient room temperatures. Adenine and AMP also lowered body temperature whereas 7-methylinosine and inosine only slightly influenced colonic temperature. Caffeine (50 mg/kg) injected sc, increased colonic temperature and when injected within 60 seconds of adenosine, counteracted the hypothermic effect of adenosine (50 mg/kg). Low ambient temperature (4 degrees C) accentuated the thermoregulatory effects of adenosine. Thus adenosine appears to have a hypothermic effect on body temperature regulation when administered peripherally which can be reversed by caffeine.
    Life Sciences 01/1984; 33(24):2431-8. · 2.56 Impact Factor

Publication Stats

100 Citations
26.52 Total Impact Points

Institutions

  • 1989–1991
    • Minneapolis Veterans Affairs Hospital
      Minneapolis, Minnesota, United States
  • 1984–1987
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
    • University of Minnesota Medical Center, Fairview
      Minneapolis, Minnesota, United States
  • 1985
    • Saint Catherine University
      Minneapolis, Minnesota, United States