Spontaneous activity and adipose cellularity in the genetically obese Zucker rat (fafa)

Stern, Judith S.; Johnson, Patricia R.

doi:10.1016/0026-0495(77)90104-4

Cited by 114 publications

(50 citation statements)

References 15 publications

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“…7,8 The type of obesity shared by fa/fa rats and db/db mice is not responsive to leptin, 9,10 since it is characterized by having mutant non-functional leptin receptors. 11 The special circumstances of the genetic obesity of Zucker fa/fa rats make them suitable for exploration of the mechanisms by which estrone acyl-esters carried by lipoproteins act, since Zucker fa/fa rats are hyperphagic 12 and cannot eliminate excess energy through thermogenesis, 4 two aspects essential for the slimming effect of oleoyl-estrone in normal rats. 1 In addition, the lack of responsiveness of this model to leptin may enable the relationship between leptin and lipoprotein acyl-estrone systems to be understood, which is why this study examined the effect of chronic oleoyl-estrone administered in liposomes (Merlin-2), on body weight and fat store changes in Zucker obese fa/fa rats, compared with phenotypically lean counterparts (Fa/?…”

Section: Introductionmentioning

confidence: 99%

Effect of the slimming agent oleoyl-estrone in liposomes on the body weight of Zucker obese rats

Sanchı́s

et al. 1997

Int J Obes

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OBJECTIVE: To determine whether the mechanisms by which estrone acyl-esters carried by lipoproteins induce the loss of body fat can affect Zucker fa/fa rats, since they are hyperphagic and could not eliminate excess energy through thermogenesis, two aspects essential for the slimming effect of oleoyl-estrone in normal rats. DESIGN: The rats were infused for 28 d (osmotic minipumps) with oleoyl-estrone in liposomes (Merlin-2) at a dose of 3.5 mmol/day Á kg. SUBJECTS: Lean (L) and obese (O) Zucker rats. MEASUREMENTS: Body weight changes. Oxygen consumption, body composition (water, lipid, protein), nitrogen balance, plasma chemistry. RESULTS: Treatment resulted in loss of body weight: 12.0 % (28 g) L, 9.4 % (34 g) O, mainly due to fat: 37.5 % (10.8 g) L, 11.7 % (15.5 g) O and water, preventing further increases in body weight and fat storage. Untreated rats increased their body weight: 10.5 % (24 g) L, 32.2 % (101 g) O and lipid stores: 20.3 % (5.9 g) L, 39.8 % (49.0 g) O, making the differences more marked. On day 28, glucose levels were maintained in all groups; in L, triacylglycerols increased and total cholesterol decreased; O showed no changes in plasma composition. In all rats, food intake decreased with treatment, and heat production (oxygen consumption) was unchanged (L) or slightly decreased (O). Energy expenditure per unit of fat-free mass remained unchanged. Protein balance was maintained in all groups; slimming was achieved without loss of body protein. CONCLUSION: Treatment of genetically obese rats with oleoyl-estrone in liposomes (Merlin-2) results in sustained loss of body weight ± mainly lipid, sparing protein ± for up to 28 d, essentially preventing further increase in body weight and accumulation of lipid and protein. This is achieved through lower food intake and relatively small changes (if any) in energy expenditure.

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Section: Introductionmentioning

confidence: 99%

Effect of the slimming agent oleoyl-estrone in liposomes on the body weight of Zucker obese rats

Sanchı́s

et al. 1997

Int J Obes

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“…These studies favored the interpretation that obese humans, like obese rodents, are hypoactive, and that this hypoactivity may at least contribute to the maintenance, if not to the development, of obesity. Studies demonstrating concurrent development of obesity and hypoactivity in genetically obese rodents, suggested that both changes, obesity and hypoactivity, may reflect simultaneous developmental expression of a common genetic trait (40).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, when the weight of mature hamsters doubles, their spontaneous activity levels are reduced by about 50% (4,8). Furthermore, when accumulation of excess energy results in obesity, mice (45), rats (37,40), and hamsters (5) display even greater spontaneous hypoactivity.…”

Section: Fastingmentioning

confidence: 99%

Hippocampal serotonin mediates hypoactivity in dietarily obese hamsters: A possible manifestation of aging?

Borer

Bonna

Kielb

1988

Pharmacology Biochemistry and Behavior

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BORER, K. T., R. BONNA AND M. KIELB. Hippocampal serotonin mediates hypoactivity in dietarily obese hamsters:A possible manifestation of aging? PHARMACOL BIOCHEM BEHAV 31(4) [885][886][887][888][889][890][891][892] 1988.--To determine whether endogenous opiates mediate hyperactivity in food restricted hamsters and serotonergic fibers innervating the hippocampus mediate hypoactivity in obese hamsters, food restriction and high-fat diet supplementation were used to produce significant body fat changes (8 vs. 21%). The levels and pattern of spontaneous running were examined after IP saline or naloxone HC1 (20 mg/kg) and following the infusion of vehicle and 5,7-dihydroxytryptamine creatine sulfate (4/~g/2/zl) into rostromedial septum of mature female hamsters. Septum-medial preoptic area (POA), hippocampus, hypothalamus, and cortex were dissected from the three groups as well as from two additional groups of hamsters receiving vehicle or neurotoxin. Concentrations of serotonin, norepinephrine, and dopamine were measured in these tissues by HPLC method. Fat-fed hamsters were hypoactive relative to food-restricted hamsters. Naloxone had no significant effect on running behavior. Serotonin neurotoxin increased the running activity of fat-fed hamsters to the level displayed by control hamsters by increasing the number of runs, the total activity level, the speed of running and by decreasing the duration of pause:~. Neurotoxin led to selective deletion of serotonin in the hippocampus (77~) and parietal cortex (50%). Serotonergic fiber~ innervating the hippocampus thus appear to mediate the hypoactivity that is induced by dietary obesity iv. mature hamsters. Since serotonin mediates some other manifestations of aging, and slow weight increases characterize mid-portion of hamster life span, we hypothesize that serotonergic mediation of hypoactivity is another manifestation of aging. FastingHyperactivity Naloxone Limbic forebrain MECHANISMS which regulate body energy balance and control spontaneous running behavior are interrelated. This is apparent at the time of sexual maturation in rodents when there is a rapid increase in spontaneous running activity to an all-time high at the same time as the rate of somatic growth and of weight gain rapidly decline (8). It is also evident after the onset of sexual maturity, during the period of slow weight gain when activity levels decline in inverse proportion to increases in body size (4,8,37). Thus, when the weight of mature hamsters doubles, their spontaneous activity levels are reduced by about 50% (4,8). Furthermore, when accumulation of excess energy results in obesity, mice (45), rats (37,40), and hamsters (5) display even greater spontaneous hypoactivity.Reciprocal relationship between energy regulation and spontaneous running remains intact after some neurosurgical manipulations which affect both mechanisms. In the hamster, voluntary running levels are reduced by 80% following electrocoagulative lesions of rostromedial septum (10), horizontal transection of septo-hippocam...

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“…Characteristics of obese and non-obese rats. -If we excluded those rats which were difficult to classify (6, 7, 8, 70, 81 and (Powley and Morton, 1976 ;Stern and Johnson, 1977) consider that 3-week old faifa rats already weigh significantly more than Fa/-rats. In addition, hepatomegaly has not yet set in.…”

Section: Introductionmentioning

confidence: 99%

Phenotypic variability in unweaned 3-week-old Zucker rats

Bach¹,

Boulange²,

Schirardin³

et al. 1981

Reprod. Nutr. Dévelop.

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Spontaneous activity and adipose cellularity in the genetically obese Zucker rat (fafa)

Cited by 114 publications

References 15 publications

Effect of the slimming agent oleoyl-estrone in liposomes on the body weight of Zucker obese rats

Effect of the slimming agent oleoyl-estrone in liposomes on the body weight of Zucker obese rats

Hippocampal serotonin mediates hypoactivity in dietarily obese hamsters: A possible manifestation of aging?

Phenotypic variability in unweaned 3-week-old Zucker rats

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