Effects Of Amylin Research Articles

Amylin(1–8) is Devoid of Anabolic Activity in Bone

Amylin(1-8), a cyclic peptide consisting of the eight N-terminal amino acids of the 37-amino acid peptide amylin, has been shown to induce proliferation of primary osteoblasts and to induce bone formation in healthy male mice, whereas no data on efficacy in bone disease-related models have been reported. Therefore, we evaluated any effects of amylin(1-8) in ovariectomized rats with established osteopenia, a model for postmenopausal osteoporosis. At doses up to 100 nmol/kg/day, a dose highly effective in healthy mice, amylin(1-8) was unable to increase bone mineral density in ovariectomized rats during an 8-week treatment period. Histomorphometric analysis of the tibia indicated that amylin(1-8) did not change bone histomorphometric parameters. In an attempt to verify any potential biological effects of amylin(1-8), we investigated the efficacy of this peptide in various in vitro assays. Experiments designed to confirm previously published results on the proliferative effects of amylin(1-8) on primary osteoblasts failed to show any response. Amylin(1-8) was able to partially displace (125)I-rat amylin(1-37) from amylin receptors composed of the calcitonin receptor and RAMP1, indicating specific interaction of the peptide with the amylin binding site. However, in vitro efficacy assays with amylin(1-8) in calcitonin receptor-RAMP-positive HEK293T and MCF7 cells failed to reveal any agonist activity of amylin(1-8), whereas amylin(1-37) showed the expected agonist activity. In conclusion, our results indicate that amylin(1-8) does not show agonist activity on amylin receptors, does not affect osteoblast proliferation, and is devoid of anabolic activity in bone.

Amylin suppresses acetic acid-induced visceral pain and spinal c-fos expression in the mouse

Amylin is a member of calcitonin or calcitonin gene-related peptide (CGRP) family. Immunohistochemical study revealed a dense network of amylin-immunoreactive (irAMY) cell processes in the superficial dorsal horn of the mice. Numerous dorsal root ganglion (DRG) and trigeminal ganglion cells expressed moderate to strong irAMY. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed amylin receptor mRNA in the mouse spinal cord, brain stem, cortex, hypothalamus and hippocampus. The nociceptive or antinociceptive effects of amylin were evaluated in the acetic acid-induced writhing test. Amylin (0.1, 0.5 and 1 mg/kg, intraperitoneally (i.p.) or 1–10 μg, intrathecally (i.t.)) reduced the number of writhes in a dose-dependent manner. Pretreatment of the mice with the amylin receptor antagonist salmon calcitonin (8–32), either by i.p. or i.t., antagonized the effect of amylin on acetic acid-induced writhing test. Locomotor activity was not significantly modified by amylin injected either i.p. (0.01–1 mg/kg) or i.t. (1–10 μg). Measurement of c-fos mRNA by RT-PCR or proteins by Western blot showed that the levels were upregulated in the spinal cord of mice injected with acetic acid and the increase was attenuated by pretreatment with amylin (10 μg, i.t.). Collectively, our result demonstrates that irAMY is expressed in DRG neurons with their cell processes projecting to the superficial layers of the dorsal horn, and that the peptide by interacting with amylin receptors in the spinal cord may be antinociceptive.

Effects of amylin on bone development and egg production in hens

Amylin is a member of the calcitonin family of hormones cosecreted with insulin from the pancreatic β-cells that can act as an osteoblast mitogen and as an inhibitor of bone resorption in mice and humans. The aim of this study was to investigate the role of amylin on bone formation and some egg parameters in hens. The study was performed in 60 hens aged 10 wk. Thirty hens constituting the treatment group were s.c. injected with amylin at a 75 μg/kg dose every other day. The remaining hens were used as the control group. Five birds from the treatment and control groups were slaughtered at 14, 16, 18, and 20 wk of age and serum and bone parameters were compared between the treatment and control groups. The remaining 20 hens were fed without any amylin injection until 35 wk. All hens at the end of the 35th week were slaughtered and then serum, bone, and egg parameters were assessed. In the treatment group, bone calcium levels increased, whereas serum calcium levels decreased. This dose of amylin also increased the cortical width of tibiotarsuses in hens. Eggshell thickness was found thicker in the treatment group than in the control group. Overall, the results of this study suggest that amylin may stimulate the bone and eggshell quality by increasing calcium uptake from the bloodstream and may influence the sustainability of yield in hens.

Effect of amylin on islet cell secretion

Effect of amylin on islet cell secretion

Effects of amylin on food intake, weight gain and body composition following exposure to chronic social stress

Effects of amylin on food intake, weight gain and body composition following exposure to chronic social stress

Noradrenergic neurons of the area postrema mediate amylin's anorectic action

Peripheral amylin inhibits food intake via activation of the area postrema (AP). 59% of amylin-activated AP neurons are noradrenergic (NA), i.e., they express dopamine-beta-hydroxylase (DBH). Here, we wanted to testwhether APNAneuronsmediate amylin’s anorectic effect.We performed a specific lesion of AP NA neurons using a saporin conjugated to an antibody against DBH (DSAP). IgG-saporin was used in sham controls. After 2–3 weeks necessary for neuronal degeneration, we tested the rats for the effect of amylin (5 or 20_g/kg BW, s.c.) to reduce food intake. In a terminal experiment, the rats received amylin (20_g/kg) or saline; brain sections with the AP and nucleus of the solitary tract (NTS) were stained for DBH to assess lesion success and for c-Fos expression to evaluate amylin-induced neuronal activation. DBH staining revealed that 10 DSAP-injected rats had NA lesion equal to or above 50%, defined as successful; 6 had lesions below 50%. Daily food intake and body weight gain did not differ between lesioned and sham groups. Amylin-induced anorexia was observed in sham rats with both amylin doses, while rats with a successful lesion had no significant reduction in eating after either amylin dose. Rats with lesions below 50% only ate less after the higher amylin dose. In contrast to sham-lesioned animals, successfully NA-lesioned rats did not show amylin-induced c-Fos expression in the AP and NTS. These results provide first evidence for a functional role of NA neurons in the AP in the mediation of amylin’s anorectic effect.

Amylin prevents TRAIL-mediated apoptotic effects of reserpine in the rat gastric mucosa

We have previously shown that amylin has a protective effect upon the damaged rat gastric mucosa via a cytokine-mediated mechanism. Here, the effects of amylin on the proapoptotic cytokine TNF-related-apoptosis-inducing-ligand (TRAIL) were tested in the rat gastric mucosa damaged by reserpine administration in vivo. Intraperitoneal administration of reserpine in adult male Sprague–Dawley rats resulted in increased TRAIL expression in the gastric mucosa. Immunohistochemistry showed that the TRAIL death-receptor 5 (DR5) was constitutively expressed by the mucosa cells. Western blot showed that pretreatment of reserpine-treated rats with amylin was associated with attenuated expression of TRAIL. In the same samples, we also investigated about TRAIL-related signaling and observed that activation of caspases-8 and -3 occurs in parallel to increased TRAIL expression in rats treated with reserpine. Similarly to the latter, activation of caspases was attenuated in rats pretreated with amylin. Treatment with reserpine was associated with increased expression of the proapoptotic protein Bax, whereas that of the antiapoptotic protein Bcl-2 was significantly decreased. Amylin prevented the effects of reserpine on these genes. Reserpine sets into motion mechanisms of apoptosis in the rat gastric mucosa, which appear mediated, at least in part, by TRAIL. In addition, TRAIL downstream signaling is activated along with subversion of gene expression related to apoptosis. Amylin was able to prevent detrimental effects of reserpine. Finally, amylin and related molecules may be envisioned as protective agent in gastric mucosa damage.

Central amylin causes more potent anorexigenic effects in chicks selected for low rather than high body weight

Amylin is a 37 residue peptide that is co‐released with insulin from the pancreas and potently reduces appetite. In the present study, we tested the effects of intracerebroventricularly (ICV) injected amylin in chicken models of hypo‐ and hyper‐phagia. These chicken models have been divergently selected for low (LWS) or high (HWS) body weight for nearly 50 generations and contain anorexic and obese individuals. In experiment one, the anorexigenic effects of amylin were more potent in line LWS, than in line HWS. Chicks in line LWS responded to all doses of amylin tested (128, 256 or 512 pmol) with reduced food intake during the 180 min observation period, whereas food intake was only reduced in HWS chicks treated with 256 and 512 pmol. Line HWS chicks treated with all doses of amylin reduced water intake, but water intake was not affected in line LWS. In experiment two, the magnitude of decreased food pecks after ICV amylin (256 nmol) was greater in line HWS than LWS. Other behaviors including exploratory pecking, jumps, escape attempts, drinks, defecations, and time spent standing, perching, sitting or preening were not affected by amylin treatment. Therefore, amylin does not appear to be associated with behaviors that may be competitive with appetite. These results may provide insights into physiological mechanisms associated with inherited body weight dysfunctions in a variety of species, including humans.

Antiobesity effects of the β-cell hormone amylin in combination with phentermine or sibutramine in diet-induced obese rats

To characterize the interactive effects of amylin with phentermine or sibutramine on food intake, body weight/composition and gene expression in diet-induced obese (DIO) rats. DIO rats were intraperitoneally injected with a single dose of amylin (10 microg kg(-1)) and/or phentermine (1 mg kg(-1)) or chronically infused with amylin (100 microg kg(-1) d(-1)) or vehicle with or without phentermine (0.5-10 mg kg(-1) d(-1)) or sibutramine (3 mg kg(-1) d(-1)) using two surgically implanted subcutaneous osmotic mini-pumps. Twenty-four hour food intake, locomotor activity and components of meal microstructure (meal size, latency, duration and intermeal interval) were measured following acute administration (amylin, phentermine or amylin+phentermine). Body weight and composition (for amylin and/or sibutramine or phentermine) and metabolism-related gene mRNA expression in the liver (fatty acid synthase, stearoyl-CoA desaturase-1 and carnitine palmitoyltransferase-1) and brown fat (beta-adrenergic receptors and uncoupling protein-1) were measured (for amylin and/or phentermine) after sustained infusion (2 weeks). Acute co-administration of amylin (10 microg kg(-1)) and phentermine (1 mg kg(-1)) reduced acute food intake (up to 19 h) more than either monotherapy. In two studies, sustained subcutaneous infusion of amylin for 2 weeks decreased cumulative food intake (22%) and vehicle-corrected body weight gain ( approximately 4-8%). Phentermine's anorexigenic (10-17%) and weight-reducing effects ( approximately 0-5%) were only evident at the highest dose tested (10 mg kg(-1) d(-1)). Combination of amylin (100 microg kg(-1) d(-1)) and phentermine reduced food intake (30-43%), body weight (8-12%) and adiposity to a greater extent than either monotherapy. Amylin prevented phentermine-induced reductions in UCP-1 mRNA in brown adipose tissue. When amylin+sibutramine were infused, mathematically additive decreases in food intake (up to 45%) and body weight (up to 12%) were evident. Similar to amylin+phentermine treatment, amylin+sibutramine mediated weight loss was attributable to significant reductions in fat mass. Combined treatment of DIO rats with the pancreatic beta-cell hormone amylin and phentermine or sibutramine resulted in additive anorexigenic, weight- and fat-reducing effects.

Leptin responsiveness restored by amylin agonism in diet-induced obesity: Evidence from nonclinical and clinical studies

Body weight is regulated by complex neurohormonal interactions between endocrine signals of long-term adiposity (e.g., leptin, a hypothalamic signal) and short-term satiety (e.g., amylin, a hindbrain signal). We report that concurrent peripheral administration of amylin and leptin elicits synergistic, fat-specific weight loss in leptin-resistant, diet-induced obese rats. Weight loss synergy was specific to amylin treatment, compared with other anorexigenic peptides, and dissociable from amylin's effect on food intake. The addition of leptin after amylin pretreatment elicited further weight loss, compared with either monotherapy condition. In a 24-week randomized, double-blind, clinical proof-of-concept study in overweight/obese subjects, coadministration of recombinant human leptin and the amylin analog pramlintide elicited 12.7% mean weight loss, significantly more than was observed with either treatment alone (P < 0.01). In obese rats, amylin pretreatment partially restored hypothalamic leptin signaling (pSTAT3 immunoreactivity) within the ventromedial, but not the arcuate nucleus and up-regulated basal and leptin-stimulated signaling in the hindbrain area postrema. These findings provide both nonclinical and clinical evidence that amylin agonism restored leptin responsiveness in diet-induced obesity, suggesting that integrated neurohormonal approaches to obesity pharmacotherapy may facilitate greater weight loss by harnessing naturally occurring synergies.

In-vitro and in-vivo antagonistic action of an anti-amylin Spiegelmer

The anorectic and dipsogenic effects of the pancreatic hormone amylin are mediated by the area postrema and the subfornical organ. We tested the effectiveness of a new amylin antagonist, a so-called RNA Spiegelmer, by electrophysiological in-vitro recordings from the rat subfornical organ and by immunohistological c-Fos studies in the area postrema. Amylin's excitatory effect on subfornical organ neurons was blocked by the anti-amylin Spiegelmer. Peripheral administration 5 h prior to amylin also suppressed the amylin-induced activation (c-Fos expression) in the area postrema. The biostable anti-amylin Spiegelmer may be therapeutically beneficial in conditions associated with high plasma amylin levels, such as cancer anorexia occurring during certain pancreatic tumors.

Pharmacological actions of the peptide hormone amylin in the long-term regulation of food intake, food preference, and body weight

The ability of amylin to reduce acute food intake in rodents is well established. Longer-term administration in rats (up to 24 days) shows a concomitant reduction in body weight, suggesting energy intake plays a significant role in mediating amylin-induced weight loss. The current set of experiments further explores the long-term effects of amylin (4-11 wk) on food preference, energy expenditure, and body weight and composition. Furthermore, we describe the acute effect of amylin on locomotor activity and kaolin consumption to test for possible nonhomeostatic mechanisms that could affect food intake. Four-week subcutaneous amylin infusion of high-fat fed rats (3-300 microg.kg(-1).day(-1)) dose dependently reduced food intake and body weight gain (ED(50) for body weight gain = 16.5 microg.kg(-1).day(-1)). The effect of amylin on body weight gain was durable for up to 11 wks and was associated with a specific loss of fat mass and increased metabolic rate. The body weight of rats withdrawn from amylin (100 microg.kg(-1).day(-1)) after 4 wks of infusion returned to control levels 2 wks after treatment cessation, but did not rebound above control levels. When self-selecting calories from a low- or high-fat diet during 11 wks of infusion, amylin-treated rats (300 microg.kg(-1).day(-1)) consistently chose a larger percentage of calories from the low-fat diet vs. controls. Amylin acutely had no effect on locomotor activity or kaolin consumption at doses that decreased food intake. These results demonstrate pharmacological actions of amylin in long-term body weight regulation in part through appetitive-related mechanisms and possibly via changes in food preference and energy expenditure.

Amylin causes anorexigenic effects via the hypothalamus and brain stem in chicks

This study was conducted to determine the effects of amylin on appetite-related processes in chicks. Broiler chicks were centrally and peripherally injected with amylin, and feed and water intake were quantified. Feed intake was reduced after both central and peripheral amylin, but water intake was not affected. To determine if the hypothalamus and brainstem were involved in the anorexigenic effect, chicks were centrally and peripherally injected with amylin, and c-Fos immunoreactivity was quantified in the lateral hypothalamus (LH), ventromedial hypothalamus (VMH), area postrema (AP) and the nucleus of the solitary tract (NTS). Amylin decreased c-Fos immunoreactivity in the LH, did not affect the VMH, and increased c-Fos immunoreactivity in the AP and NTS. To determine if alimentary transit time was affected, chicks received central amylin and were gavaged with chicken feed slurry containing a visible marker. Amylin-treated chicks had increased alimentary canal transit time. Chicks also responded to central amylin with increased anxiety-related behaviors and increased plasma corticosterone concentration. These results demonstrate that amylin affects feeding, alimentary canal transit, and behavior through hypothalamic and brainstem mechanisms in chicks.

Diet-Derived Nutrients Modulate the Effects of Amylin on c-Fos Expression in the Area Postrema and on Food Intake

The pancreatic hormone amylin decreases food intake via activation of area postrema (AP) neurons. We investigated whether amylin’s potency to reduce food intake and to induce c-Fos expression in the AP/nucleus of the solitary tract region is affected by the feeding conditions and specifically by the macronutrient composition of the diet. Whereas a low dose of amylin (5 µg/kg s.c.) induced very little c-Fos expression in ad libitum chow fed rats, it caused a strong c-Fos expression in 24-hour food-deprived rats and in rats that received a nutrient-deficient non-caloric mash (NCM; vanilla-flavoured cellulose) 24 h before injection. To reveal the contribution of single nutrients to the low c-Fos expression after chow feeding, amylin-induced c-Fos was analyzed after feeding NCM that was selectively supplemented with glucose, fat (lard), or protein (casein), matching the intake of these nutrients of chow-fed rats. While the rats fed NCM supplemented with glucose or fat displayed an equally strong amylin-induced activation as fasted rats or rats fed plain NCM, a significantly lower c-Fos expression was observed in rats fed a protein-supplemented NCM or a NCM containing all three nutrients. In line with this lower activation, the same dose of amylin failed to reduce food intake in NCM/protein-fed rats, while amylin caused a reduction in feeding when animals received NCM, NCM/glucose, or NCM/fat. Interestingly, amylin effectively reduced food intake in ad libitum chow fed rats despite the low level of amylin-induced c-Fos expression in the AP under these conditions. We conclude that the anorectic potential of amylin may be attenuated by diet-derived proteins, whereas this effect appears to be overridden when the amount of carbohydrates/fat is high relative to the protein content, such as, e.g., in standard chow.

Nutrients modulate amylin's effect on c-Fos expression in the area postrema and on food intake.

The pancreatic hormone amylin decreases food intake via an activation of area postrema (AP) neurons. In immunohistochemical (c-Fos) and behavioral studies we investigated whether amylin's effects are modulated by diet-derived macronutrients. Compared to ad libitum chow-fed rats amylin produced a strongly increased c-Fos expression after 24 h food deprivation and after 24 h feeding of a nutrient deficient non-caloric diet (NCD, vanilla-flavored cellulose). In order to explore the role of single nutrients, c-Fos expression was analyzed after feeding NCD that was selectively supplemented with glucose, fat (lard) or protein (casein) matching the intake of these nutrients of chow fed rats. While the supplementation with glucose and fat did not alter the amylin-mediated c-Fos response when compared to NCD, a significantly lower amylin-induced activation was observed in rats fed a protein supplemented NCD or a NCD containing all three nutrients. In line with this lower activation, the same dose of amylin (5 μg/kg sc) failed to reduce food intake in NCD/protein fed rats, while amylin caused anorectic responses when animals received NCD, NCD/glucose or NCD/fat. Interestingly, amylin effectively reduced food intake in ad libitum chow fed rats, although the amylin-induced c-Fos expression in the AP was very low under these conditions. We conclude that diet-derived proteins may attenuate amylin's anorectic effect via an AP-dependent mechanism. However, this effect appears to be overridden by downstream mechanisms when the protein content is low relative to the content of carbohydrates/fat (chow).

Lesion of the lateral parabrachial nucleus attenuates the anorectic effect of peripheral amylin and CCK

Amylin and CCK activate the area postrema (AP)/nucleus of the solitary tract (NTS) – lateral parabrachial nucleus (LPBN) – central amygdala (CeA) pathway. However, except for the brainstem structures the role of these nuclei for the anorectic effect of these peptides is not yet well characterized. The current study investigated the role of the LPBN in mediating the inhibitory effect of peripheral amylin and CCK on feeding behavior. Rats with electrolytic lesions in the LPBN (LPBN-X) were used in behavioral as well as in immunohistological c-Fos studies. LPBN-X significantly reduced the anorectic effect of amylin (5 μg/kg, i.p.). The effect of a higher amylin dose (10 μg/kg, i.p.) was only slightly attenuated in the LPBN-X rats. In agreement with previous studies, LPBN lesions also reduced the inhibitory effect of CCK on food intake. In the immunohistological experiments, amylin and CCK induced c-Fos expression in the AP, NTS, LPBN and CeA in the SHAM rats. Both the amylin- and CCK-induced activation of the CeA was completely abolished in the animals with a LPBN lesion. These results clearly suggest that the signal transduction pathway between the AP/NTS and CeA has been disrupted by the LPBN ablation. We conclude that the LPBN is a crucial brain site mediating the anorectic effect of amylin and CCK. Furthermore, an intact LPBN seems to be essential for the c-Fos response in the CeA induced by these peptides.

Histamine H 1-receptors differentially mediate the action of amylin on hypothalamic neurons in control and in overweight rats

The hypothalamic arcuate, dorsomedial and paraventricular nuclei are involved in regulation of body weight and food intake and contain binding sites for the anorexigenic amylin. Effects of amylin on medial arcuate and paraventricular neurons studied in adult rats overweight through early postnatal overfeeding in small litters (SL) differed from those of control litters (CL). Now we observed that also dorsomedial neurons respond differentially to this satiety signal. They were significantly inhibited by amylin in SL but not CL rats. Since the histaminergic system seems to be involved in mediating effects of amylin, we studied the role of histamine H 1-receptors. Single unit activity was recorded in brain slices of CL and SL rats in each of the three hypothalamic nuclei. The histamine H 1-receptor antagonist pyrilamine differentially altered or reduced responses to amylin, not depending on the kind of litter but on the functional effect of the peptide. Pyrilamine prevented significant inhibition of medial arcuate neurons in controls as well as inhibition of dorsomedial and paraventricular neurons in SL rats. Searching for further mechanisms possibly contributing to the change of neuronal responses we found that in the presence of a GABA A-receptor antagonist amylin induced a significant inhibition of medial arcuate neurons in SL rats similar to that in CL without antagonist. Activation of medial arcuate neurons expressing the orexigenic neuropeptide Y and inhibition of dorsomedial and paraventricular neurons in SL rats may in vivo contribute to hyperphagia and overweight. Histamine H 1-receptors and GABA A-receptors seem to be differentially involved in mediation of these effects.

Modulation of the satiating effect of amylin by central ghrelin, leptin and insulin

Amylin is a pancreatic hormone that is considered to be a satiating signal acting on neurons of the area postrema (AP) in the hindbrain. The adiposity signals leptin and insulin act in the hypothalamus to influence feeding. They also enhance the hindbrain's responsivity to satiating signals, e.g. cholecystokinin (CCK). The orexigenic hormone ghrelin is thought to use the same hypothalamic pathways as leptin and insulin, with opposite actions on feeding behaviour. In fact, CCK and ghrelin also seem to interact in the control of feeding. Because CCK's anorectic effect depends on endogenous amylin, the aim of this study was therefore to evaluate a possible functional interaction between amylin and these hormones on short-term food intake in rats. The experiments were performed with male Wistar rats. Intracerebroventricular injection (i3vt) of an orexigenic dose of ghrelin (5 ng/5 μl) reduced but did not completely reverse the intraperitoneal amylin (5 μg/kg)-induced inhibition of food intake. In comparison, administration of a sub-threshold dose of ghrelin (3 ng/5 μl) did not affect the anorexigenic action of peripheral amylin. Leptin administered into the third ventricle (i3vt; 3.5 μg/5 μl) and intraperitoneal amylin (5 μg/kg) synergistically reduced food intake in chow-fed rats. I3vt insulin, administered at a sub-threshold dose (0.5 mU/5 μl), significantly enhanced the response to peripheral amylin. These results indicate that the lipostatic signals leptin and insulin may synergize with amylin to reduce food intake. In contrast, under the conditions tested, the orexigenic hormone ghrelin does not seem to influence the feeding response to peripheral amylin.

Protective effects of amylin on reserpine-induced gastric damage in the rat

Here we show that the vasoactive peptide amylin protects against reserpine-induced gastric injury in the rat, resulting in lower score of gastric lesions. Hepatocyte growth factor (HGF), its c-Met receptor and cyclooxygenase-2 (COX-2) expression, usually increased in course of reserpine-induced gastric damage, was decreased in rats treated with amylin. Pretreatment with the specific amylin receptor antagonist AC187 abrogated the gastroprotective effects of amylin and restored high expression levels of HGF, c-Met and COX-2. Our data suggest that protective effects of amylin upon the gastric mucosa are specific and eventually involve modulation of HGF, c-Met and COX-2 expression.

The acute effect of amylin and salmon calcitonin on energy expenditure

The pancreatic B-cell hormone amylin is known to be involved in the regulation of meal ending satiation and it also shares typical features of adiposity signals. Chronic amylin administration has recently been shown to increase energy expenditure under certain conditions. Here we investigate the acute effect of peripheral administration of amylin or its agonist salmon calcitonin (sCT) on energy expenditure and respiratory quotient (RQ). First, rats were injected with amylin (5 μg/kg IP) or saline just before dark onset. Despite significantly decreased food intake in amylin-treated rats compared to control until 2 h post-injection ( p < 0.05), amylin did not influence energy expenditure or RQ. Reduced food intake, which reduces energy expenditure, may have confounded a stimulatory effect of amylin on energy expenditure. Therefore, in the second experiment, amylin (1, 5 and 10 μg/kg IP) or saline was injected in the middle of the light phase ( t = 0 h) without access to food during 3 h post-injection. Amylin had no significant effects on energy expenditure or RQ. In a similar paradigm, the effect of sCT (0.1, 1.0 and 5.0 μg/kg IP) was tested. During food restriction, 5.0 μg/kg sCT significantly stimulated energy expenditure compared to control ( p < 0.05). Subsequent to refeeding at t = 3 h, energy expenditure was decreased compared to control at t = 8 h and t = 10 h after 5.0 μg/kg sCT, probably due to sCT's strong anorectic action. Thus amylin may prevent the compensatory decrease in energy expenditure normally seen in animals that eat less. The longer acting sCT stimulated energy expenditure in animals without food access.