腺苷一磷酸激活蛋白激酶与采食量调节

<正>腺苷一磷酸激活蛋白激酶(AMPK)的概念首次出现在1988年。近几年的研究表明,AMPK在调节细胞能量代谢上起着重要作用,被称作细胞内的“燃料开关”,在动物抵御和适应环境应激的过程中也起着重要作用。最新研究显示,AMPK通过一些激素和养分等途径参与采食量的调节。本文总结了AMPK在采食量调节中的作用和可能机制,揭示研究其与动物营养代谢的重要性关系。     

Histochemical localization of inhibin and activin alpha, beta A and beta B subunits in rat gonads.

The localization of alpha, beta A and beta B subunits of inhibin/activin polypeptides was studied in the ovary and testis of sexually mature, immature, and embryonic rats. Specific staining with these three subunits was also evident in the oocytes from embryonic to mature female rats. This result suggests that inhibin- and activin-like substances may be produced in the oocytes and these substances may play a role in the oocyte growth and differentiation. Judging from the intensity of immunoreaction in mature female rats, the three subunits should be produced more abundantly in luteal cells than in the granulosa cells. Immunoreactive alpha, beta A and beta B subunits were observed in the cummulus oophorous in the morning (11:00), but not in the evening (23:00) on proestrus. The results are in well agreement with the previous report that inhibin alpha and beta A subunit mRNA signals decline on proestrus evening. It is supposed that the cyclic change may be related with physiological phenomena prior to the ovulation, such as primary gonadotropin surges, loss of cummulus-oocyte gap junctions, or germinal vesicle breakdown. In both germ cells and Sertoli cells of the testis, alpha, beta A and beta B subunits were more abundant in the embryonic rat than in the mature rat. Although clear reactions with beta A and beta B subunits were detected in Leydig cells, alpha subunit was not detectable in the cells throughout the developmental stages examined.     

Expression of inhibin/activin subunits in the ovaries of fetal and neonatal mice

In the present study, the expression of inhibin/activin subunits in the mouse ovary from 13 days post-coitus (dpc) to 30 days postpartum (dpp) was investigated. Circulating FSH, LH, inhibin A, and inhibin B in neonatal to 30 dpp ovaries were measured. Inhibin/activin subunits (alpha, beta(A), beta(B) ) were weakly stained in 13 dpc ovarian stromal cells and increased with age. Inhibin alpha subunit was immunolocalized in follicular granulosa cells at each developmental stage. In 30 dpp ovaries, several large antral follicles were strongly stained for inhibin alpha subunit. Inhibin beta(A) subunit was weakly immunolocalized in granulosa cells until 20 dpp. Moreover, 2 to 3 antral follicles from 20 to 30 dpp were strongly stained for inhibin beta(A) subunit. There was relatively high immunoactivity for inhibin beta(B) subunit in neonatal to 30 dpp mouse ovaries. All three inhibin subunits were stained in theca-interstitial cells from 15 dpp onward. RIA data showed that a temporal increase in circulating FSH occurred around 10 dpp, while the plasma concentrations of LH were sustained at a relatively higher level from 8 to 15 dpp. Inhibin B was detectable in circulation early at 1 dpp (day of birth), and a clear increase in inhibin B occurred around 8 dpp. Circulating inhibin B gradually increased from 20 dpp to 30 dpp, indicating a negative correlation with FSH. Inhibin A levels were only measured on 25 and 30 dpp, and the levels were low. These results suggest that inhibins play an important role in early folliculogenesis in mice. In addition, inhibin B seems to be the main functional isoform from the neonatal to prepubertal stage in the mouse ovary.     

The regulation of food intake and correlated energy balance in mice.

In order to study the regulation of food intake and correlated body energy metabolism, the effect of restricted feeding during the light period in female IVCS mice was investigated. Access to food and water was restricted (RF group) for 3 weeks only from 10:00 hr to 17:00 hr, and that in the control group remained ad libitum. After starting food restriction (day 1), mean food intake decreased to 10% of the control value, then rose sharply, over the next 3 days, to reach 70% of the control value. Then, it decreased gradually to about 50% of the control value and remained at this low level thereafter. There was no significant difference between mean body weights for the two groups. Feed-efficiency was considered, therefore, to be higher in the RF than in the control group. RF-treatment increased plasma corticosterone levels and decreased locomotor activity. However, the diurnal patterns of plasma corticosterone levels and locomotor activity observed suggest that the circadian rhythm, synchronized with the light-dark cycle, persisted during RF-treatment. These findings suggest that restricted feeding during the naturally inactive phase (light period) induces a decrease in food intake. Animals seem to adapt to underfeeding, at least partly, by increasing feed-efficiency and plasma corticosterone levels and decreasing locomotor activity.     

Involvement of corticosterone in food intake, food passage time and in vivo uptake of nutrients in the chicken (Gallus domesticus)

To evaluate the effect of corticosterone on nutrient transport, 10-week-old male chickens were grouped in 4 categories and treated as follows: sham-operated, adrenalectomised, corticosterone (4 mg/kg injected subcutaneously for 5 d) in both sham-operated and adrenalectomised. The food intake, food passage time and uptake of calcium, phosphorus and glucose were determined by standard procedures. Corticosterone administration to both sham-operated and adrenalectomised groups stimulated significantly higher food intake, delayed food passage time and increased uptake of calcium, phosphorus and glucose, as compared to sham-operated control and adrenalectomised groups. Corticosterone administration increased absorption of these nutrients significantly more in the adrenalectomised group than in the sham-operated controls. Corticosterone also significantly elevated the plasma concentrations of these nutrients. The responses to the hormone were significantly greater in adrenalectomised birds. It is concluded that corticosterone increases food intake and retention and the absorption of calcium, phosphorus and glucose in the alimentary tract.     

Immunolocalization of inhibin/activin subunits in the shiba goat fetal, neonatal, and adult testes

The objective of this study was to investigate the cellular immunolocalization of inhibin alpha and inhibin/activin (betaA and betaB) subunits in the fetal, neonatal and adult testes of Shiba goats. The testes were obtained from a fetus at 90 days, a neonate at 15 days, and two adult Shiba goats (both of 3 years old). The sections of testes were immunostained by the avidin-biotin-peroxidase complex method (ABC) using polyclonal antisera raised against porcine inhibin alpha, inhibin/activin betaA, and inhibin/activin betaB. Inhibin alpha and inhibin/activin (betaA and betaB) subunits were expressed in Leydig cells, but not in the Sertoli cells of the fetus with a weak immunostaining. An increase in the number of positive cells and a more intense immunohistochemical signal for inhibin alpha and inhibin/activin (betaA and betaB) subunits were observed in the Leydig cells of neonatal testes. Moreover, inhibin alpha, betaA, and betaB subunits were expressed in the Sertoli cells and Leydig cells of adult testes, respectively. These results suggest that Shiba goats testes have the ability to synthesize inhibins in the fetus, neonate, and adult, and the cellular localization of inhibin/activin subunits showed age-related changes in fetal, neonatal, and adult testes of Shiba goats.     

Potential of chemical regulation of food intake and body weight of broiler breeder chicks

1. Two experiments were performed to evaluate the potential of phenylpropanolamine hydrochloride and monensin sodium as appetite- and weight-control agents for Indian River broiler breeder chicks. 2. In experiment 1, a total of 300 day-old sexed broiler breeder chicks were individually weighed and placed in battery cages. They were randomly assigned to 5 dietary treatments, namely 0, 50, 100, 200 and 400 mg/kg of phenylpropanolamine hydrochloride added to a maize-soyabean meal basal diet. 3. In experiment 2, a total of 400 day-old sexed broiler breeder chicks were randomly assigned to 10 dietary treatments which were a combination of two concentrations of dietary crude protein (200 and 150 g/kg) and 5 different concentrations of added drugs in the diet, namely 0, 500 and 800 mg/kg of phenylpropanolamine hydrochloride and 200 and 300 mg/kg of monensin sodium. 4. Food consumption and body weight gain were significantly reduced by feeding diets containing the drugs but mortality was not significantly affected. Birds showed evidence of increased tolerance, with age, to phenylpropanolamine but not to monensin. 5. Monensin sodium, at high inclusion rates, was found to be a more potent and effective appetite- and growth-depressing agent for broiler breeder chicks than phenylpropanolamine and may have application in broiler breeder production using an ad libitum feeding programme.     

Effects of food intake regulation on the energy metabolism of hens and cockerels of a layer strain

1. Indirect calorimetry was used to study the effects on the energy metabolism of cockerels and hens after peak lay of a hybrid layer strain of regulating food or energy intake to 80% of ad libitum for an extended period of time. 2. Regulation of food intake decreased fasting and fed heat productions per bird and per unit metabolic body weight (kg0.75). 3. Maintenance energy requirements (per kg0.75) of both sexes were reduced about 20% by regulation; maintenance requirements of cockerels were about 30% lower per kg0.75 than hens on the same treatments. 4. Reducing the intake of all nutrients by 20% had the same effect on the energy metabolism of cockerels as restricting energy alone by the same amount. 5. Gross efficiency of egg production, in terms of both mass and energy, was higher when intake was regulated. During weeks 21 to 52 of restriction, daily egg mass output was significantly higher in hens fed ad libitum. 6. After 52 weeks of food regulation, restricted hens weighed 20% less and their total carcass energy was 36% less than hens fed ad libitum; similar effects were found in the cockerels.     

激活素对生殖的作用及其作用机制

主要介绍了激活素对生殖的作用,激活素亚基βA和βB及其受体在生殖系统中的表达分布,以及激活素的作用机制。激活素A对动物生殖具有刺激作用,但这种作用具有时间的特异性;激活素的主要作用除了受激活素受体、还受卵泡抑素和抑制素等的调节作用。     

Food intake and growth in chickens given food in the wet form with and without access to drinking water

1. Individually caged growing chickens were offered a commercial grower food mixed with 1–5 to 2^‐25 times the weight of water and the effects, compared to giving the same food in air‐dry form, on food intake, body weight gain and carcase composition were investigated.

2. Male broilers (24) were given either a grower food in the air‐dry form with access to drinking water or the same food mixed with 2–0 parts of water (700 g water/kg of mixed food) with no drinking water from 28 to 49 d of age. From 49 to 63 d all birds were given dry food and drinking water and were then killed for carcase analysis. Food intake and weight gain were significantly increased during the wet‐feeding period, as was carcase protein but not abdominal or carcase fat at the end of the experiment.

3. Five male broilers were given each of 5 dietary treatments containing 0 (control), 1.5, 1.75, 2.0 and 2.25 times added water (640, 673, 700 and 723 g water/kg) from 28 to 49 d. Food intakes, body weight gains and carcase weights were significantly increased for all water additions compared with dry food, but there were no significant differences between different water additions.

4. Female broiler chicks responded to wet feeding (700 g water/kg) in a similar manner to males and the dry matter approximate digestibility was increased from 0.65 for the dry food to 0.73 for the wet.

5. Cockerels of an egg‐laying strain did not increase their intake of dietary dry matter when it was fed in the wet form (700 g water/kg), but there was a significant increase in body weight gain.

6. Male broilers were offered wet food (700 g water/kg) with or without access to drinking water. There was equal stimulation of food intake, growth and carcase weight with both wet‐feeding treatments.

7. Providing food mixed with sufficient water to give a porridge‐like consistency significantly increased weight gains in each of the five experiments and significantly improved food conversion efficiency in three of the five. It is not necessary to withold drinking water in order to obtain this effect.     

Involvement of food intake in the decreased energy retention associated with single deficiencies of lysine and sulphur-containing amino acids in growing chicks.

1. Growth and energy utilisation were determined in growing chicks fed ad libitum on diets deficient either in lysine (5.95 g/kg) or in sulphur-containing amino acids (SAA, 3.5 g/kg). Food intake, body weight gain, energy retained as protein and as fat, and total energy retention were significantly (P less than 0.05) reduced by single deficiencies of either lysine or SAA. 2. Another two experiments were conducted to determine if the decreased total energy retentions in chicks fed on diets deficient in lysine (experiment 3) or SAA (experiment 4) were associated with reduced food intake, by using tube-feeding to control the amount and pattern of food consumption. Chicks fed on diets deficient in lysine or SAA retained less energy as protein and more energy as fat than the control chicks. Neither total energy retention nor heat increment was affected by these deficiencies. Total energy retention was proportional to metabolisable energy (ME) intake alone. 3. It is concluded that the decreased total energy retentions caused by single deficiencies of lysine and SAA were associated with decreased food intake.     

抑制素免疫在动物繁殖调控中的应用

从精液、卵泡液和睾丸网液中提取。迄今,已从动物的精液、卵泡液和睾丸网液中提取得到均一的抑制素,然而,由于组织(液)中抑制素含量较低,所以得到的抑制素数量非常有限,而且成本很高。     

Seasonal changes in spermatogenesis and immunolocalization of inhibin/activin subunits in the wild male ground squirrel (Citellus dauricus Brandt)

The objective of this study was to investigate the seasonal changes in spermatogenesis and the immunolocalization of the inhibin alpha and inhibin/activin (betaA and betaB) subunits during the breeding and non-breeding seasons in the wild male ground squirrel. The testicular weight and size and seminiferous tubule diameter were measured, and histological observations of testes were performed. The sections of the testes were immunostained by the avidin-biotin-peroxidase complex method (ABC) using polyclonal antisera raised against porcine inhibin alpha, inhibin/activin betaA and inhibin/activin betaB during the breeding and non-breeding seasons. There were marked variations in testicular weight and size and seminiferous tubule diameter between the breeding and non-breeding seasons, and all types of spermatogenic cells, including spermatozoa, were found in the breeding season. In addition, immunoreactivity was also detected for the inhibin alpha, betaA and betaB subunits in Sertoli and Leydig cells during the breeding season, but immunostaining was only present for the inhibin alpha and inhibin/activin betaB subunits in Sertoli cells during the non-breeding season. These results suggest that seasonal changes in testicular weight and size and seminiferous tubule diameter of wild ground squirrels are correlated with changes in spermatogenesis, and the cellular localization of the inhibin/activin subunits showed season related changes in the breeding and non-breeding seasons.     

Blood glucose levels and food intake in the domestic chicken

Hyperglycemia was produced in female Brown Leghorn fowls by oral or intravenous injection of glucose solutions, at high and low levels of feeding motivation. A significant effect on food intake during a subsequent 15‐min test period was found only for the oral/low‐motivation condition. This may have been due to the osmotic effect of the solution on the gut rather than a true lowering of feeding motivation. It is unlikely that feeding motivation is directly related to blood glucose levels.     

Immunolocalization of inhibin/activin subunit proteins during the breeding season in testes and scented glands of muskrats (Ondatra zibethicus)

The objective of this study was to investigate the cellular immunolocalization of inhibin a and inhibin/activin (β(A) and β(B)) subunits in the muskrat testes and scented glands during the breeding season. Inhibin α and inhibin/activin (β(A) and β(B)) subunits were expressed in Sertoli cells and Leydig cells of testes and glandular cells of scented glands, respectively. Also, positive signals of inhibin α and inhibin/activin (β(A) and β(B)) subunits by Western blotting were both observed in testicular and scented glandular tissues. These results suggested that the testes and scented glands of the muskrats had the ability to synthesize inhibins and activins and that activins and inhibins might play an important role in testicular and scented glandular function in muskrats.     

Local effect of progesterone infusion into ovarian artery on activin A and inhibin alpha-subunit secretion during the middle luteal phase in gilts

The present study was undertaken to elucidate whether an increased, but physiological, amount of progesterone (P4) supplied to the porcine corpus luteum affects luteal secretion of activin A and inhibin alpha-subunit (Inhalpha) in freely moving gilts. On day 9 of the estrous cycle (EC), both ovarian arteries and both ovarian veins of gilts (n = 5) were cannulated. Progesterone was infused into the right ovarian arteries in gilts on days 10, 11 and 12 of the EC at a rate adequate to its physiological retrograde transfer found during the middle luteal phase of the EC. The P4 infusion rate was 0.62 microg/min (day 10), 2 x 0.62 microg/min (day 11) and 3 x 0.62 microg/min (day 12). The left ovarian arteries were infused with saline (control). Blood samples were collected from both ovarian veins on days 10-12 of the EC before and after P4 or saline infusion. The mean plasma activin A level in the ovarian vein ipsilateral to the P4-infused ovary was higher (P < 0.0001) on days 10-12 of the EC than this found in the contralateral ovarian vein. The level of activin A in the ovarian vein ipsilataral to the infusion of P4 was higher on days 11 (P < 0.01) and 12 (P < 0.0001) and tended to be higher (P < 0.07) on day 10 of the EC than this in contralateral ovarian vein. The level of Inhalpha in the ovarian vein ipsilateral to the P4-infused ovary on days 10-12 of the EC was not significantly different (P > 0.05) than this found in the contralateral ovarian vein. The results of the present study indicate that a local elevation of P4 concentration in blood supplying the ovary during the middle luteal phase of the porcine EC affects ovarian secretion of activin A. The effect of P4 on the secretion of activin A suggested the existence of a short regulatory loop of a positive feedback between P4 being retrogradely transferred into the ovary and the secretion of this peptide.     

The development of the regulation of food intake during ontogenesis--the effect of hyperalimentation on body weight gain in suckling rats

In an experiment, the number of young rats per nest was reduced to two in time intervals from the 1st to the 6th, from the 6th to the 11th, from the 11th to the 16th, and from the 16th to the 21st day after birth (groups P1, P2, P3 and P4 respectively). The plenty of milk available to the young for a period of five days positively influenced the body weight of the rats in group P2, whereas in the remaining groups the total weight showed no significant change in comparison with normally fed animals. The subsequent normalization of nutrition in the test young (the number of the young in nests was increased to eight) induced a decrease in weight gains in the older test animals (groups P3, P4), whereas in the 6- to 11-day-old rats (P2) the higher weight gains were retained in the next growth stages. The results give evidence that an external interference in the nutrition of rats (hyperalimentation) in the period from the 6th to the 11th day of life can influence, for a longer time, feeding behaviour and weight gains. The relative stability of the body weight of the young after the 11th day of life suggests to the functional involvement of the regulatory mechanisms controlling feed intake in this period of life.     

Voluntary food and calcium intake by the laying hen

Two experiments, each of 40 d duration, are described in which a diet rich in calcium (3.5% Ca) or one deficient in calcium (1% Ca), but with oyster shell offered separately, were fed ad libitum to four laying hens. The voluntary consumption of food and oyster shell was automatically recorded every 2 h. The hourly consumption of the high Ga diet increased during the afternoon while the daily pattern of consumption was modified by the position of the egg in the clutch.

When the low Ca diet was fed with oyster shell, the daily consumption was increased but the effect of the position of the egg in the clutch was reduced. The ingestion of oyster shell was very high between 16.00 and 20.00 h when egg calcification was in progress; after the last oviposition of the clutch this elevated level of intake remained though to a lesser degree. In relation to the stage of egg formation, the voluntary intake of oyster shell increased sharply between 4 and 12 h after the former oviposition.

These results confirm that the laying hen can discriminate between food and calcium intake. It seems that appetite for calcium is firstly related to light‐dark cycles with a modulation of the afternoon peak by ovulation and then egg shell calcification.