Nancy J. Kenney

Intracerebroventricular beta-endorphin increases food intake of rats☆

Abstract B-Endorphin (B-END), met-enkepalin (M-ENK), and DAla 2 NMe 5 -met-enkephalinamide were administered intracerebroventricularly to rats and effects on the ingestion of a liquid diet were examined. B-END significantly increased food intake in a half-hour test at a dose of 200 ng/rat. Lower or higher doses did not affect food intake. Neither M-ENK or the synthetic enkephalin analog affected ingestion of the liquid diet. These findings demonstrate rapid action of an endorphin on food intake administered at a lower dose than has previously been reported and suggest a specificity for B-END in the endorphinergically mediated hyperphagic response.

Peptides and the control of meal size

SummaryThere are now a large number of experiments demonstrating that peripheral administration of exogenous cholecystokinin or its synthetic analogue, CCK-8, reduces meal size in a number of species. The peptide interacts with other factors which influence satiety, and treatments thought to be effective in eliciting secretion of cholecystokinin have predictable effects on meal size. Cholecystokinin is effective in the genetically obese Zucker rat, obese rats with lesions of the ventromedial hypothalamus, and subdiaphragmatically vagotomized rats. Somatostatin and bombesin are also reasonable candidates for satiety factors. Intraperitoneal naloxone reduces meal size in rats, and beta-endorphin injected intraventricularly causes an increase in meal size of 50% over 30 minutes. We conclude that cholecystokinin and bombesin may interact in weight regulation and control of meal time food intake.

Diet selection following area postrema/nucleus of the solitary tract lesions.

Ten adult Long-Evans male rats were offered access to fat, protein and carbohydrate from separate sources. After adaptation to this diet, 5 animals received thermal lesions of the area postrema and adjacent caudal-medial portion of the nucleus of the solitary tract (AP/cmNTS). The remainder were sham-operated. AP/cmNTS lesioned rats ate significantly less and lost more weight than controls during the first postsurgery measurement period (Days 4-13 after lesioning). The decrease of food intake of AP/cmNTS lesioned rats was due to reduced fat consumption. Carbohydrate and protein intakes of lesioned animals did not differ from those of controls. Food intakes and weight changes of lesioned rats did not differ from those of controls during days 14-23 after lesioning. Intake of fat by lesioned animals remained low but was no longer significantly different from that of controls. Carbohydrate and protein intakes of lesioned rats increased slightly but did not differ significantly from those of nonlesioned controls.

Taste Modulation of Fluid Intake

In any discussion of “nonregulatory” or “nonhomeostatic” determinants of behavior, the influence of taste on ingestion is certain to receive at least a mention. And at first glance, the phenomena observed when animals are offered various sapid materials are impressive to one accustomed to think of animals as “finely tuned regulatory machines” (Emits and Corbit, 1973).

Area postrema/nucleus of the solitary tract ablations: Analysis of the effects of hypophagia

The effect of hypophagia following lesions of the area postrema and caudal-medial aspect of the nucleus of the solitary tract AP/cmNTS) on body-weight, water intake and preference for palatable diets was examined. Following AP/cmNTS ablation, rats reduced pelleted-food intake to a degree which was sufficient to account for the weight loss and increased water:food ratios observed. Restricting food intakes of intact rats to levels taken by lesioned animals resulted in similar weight losses and increased water:food ratios. When offered both pelleted food and milk, lesioned rats took more calories as milk than did previously food-restricted intact rats. Thus, the hypophagia of AP/cmNTS lesioned rats does not account for their increased preference for milk diets. Lesioned rats ate less high-fat diet than did intact or sham-lesioned controls and did not increase their intakes when this diet was sweetened. At autopsy, retroperitoneal and epididymal fat-pad weights accounted for less of the total body weight of lesioned animals than controls suggesting that body-fat levels are reduced following AP/cmNTS ablation.

Food Aversion Induced by Area Postrema Ablation

Rats with lesions of the area postrema (APX rats) avoid foods ingested on a regular basis during the period of severe hypophagia immediately following surgery (Tomoyasu & Kenney, 1989). The present work determined whether APX rats would also avoid foods to which they are exposed only after they have recovered from the lesion-induced hypophagia. APX and SHAM-lesion rats were fed a novel food for 8 days beginning at least 1 month after surgery when food intakes (adjusted for body weight) and weight gains of the APX rats had returned to control levels. During 24 h, two-food choice tests, APX rats avoided the food ingested a month after the ablation while avidly ingesting an alternative food, but SHAM rats showed no preference between the foods. There was no indication that this aversion developed by APX rats to foods ingested after recovery from hypophagia is weaker than that developed to foods ingested immediately after the lesion. We conclude that area postrema ablation results in the development of an unconditioned stimulus capable of supporting food-aversion conditioning which remains effective more than 1 month after the ablation. Hence, the relationship between APX-induced food aversion and hypophagia must be indirect and complex. Also, conditioning of food aversions induced by area postrema ablation alone may confound studies of the role of this structure in mediating the development of food aversions after other physiological and/or pharmacological manipulations.

Effects of ovariectomy and subsequent estradiol replacement on intake of sweet solutions

Abstract Neither ovariectomy nor subsequent estradiol replacement has any effect on the female rats ingestion of saccharine solutions of varied concentrations. This holds whether or not the animal has had experience with the sweetener prior to ovariectomy. Removal of the ovaries enhances intake of glucose solutions while replacement of estradiol reduces the glucose intake of ovariectomized rats. Modifications of glucose ingestion by ovarian hormone manipulation may reflect the influence of these hormones on mechanisms controlling food ingestion rather than any separate effect of estrogens on preference for or ingestion of sweet solutions.

Pressor Responses to Central Angiotensin II, Prostaglandin E1 and Prostaglandin E2

The effects of ovarian steroids on baseline blood pressure and on changes of mean arterial pressure in response to centrally administered angiotensin II, prostaglandin E1, and prostaglandin E2 were examined. Ovariectomized rats treated with estradiol or progesterone showed no change of resting blood pressures relative to oil-treated, ovariectomized controls. Intracerebroventricular injections of prostaglandin E1, prostaglandin E2 or angiotensin II produced significant elevations of arterial pressure of oil-treated rats. Either estradiol or progesterone treatment significantly attenuated pressor responses to prostaglandin E1 but not to prostaglandin E2 or angiotensin II injections. The duration of the blood pressure increase of estradiol-treated rats in response to angiotensin II was reduced when the animals did not have access to drinking water during the pressure monitoring session but not when water was available. These results suggest that the effects of ovarian steroids in modulating pressor responses are dependent on the particular factors which initiate the pressure increases. Possible mechanisms underlying this ovarian-steroid action are discussed.

Sex life and role identity in Taiwanese women during menopause: a qualitative study

AIM Our goal was to examine Taiwanese womens perspectives on the way menopause affected their sexual behaviour to gain an in-depth understanding of their experiences during this transition. BACKGROUND Physical symptoms associated with menopause may affect womens sexual experiences. Little is known about how menopause-related changes in sexual behaviour may affect role identity of women living in a modernizing urban culture that is still strongly rooted in traditional beliefs and attitudes. DESIGN This was a qualitative study involving face-to-face interviews using open-ended questions. METHODS During 2011-2012, eighteen peri or postmenopausal women visiting a medical clinic for gynaecological examinations or treatment were interviewed about their sexual experiences. Responses were analysed for common themes. FINDINGS Four themes were identified about the effects of menopause on womens sex life: (1) changes in physical responses during sex; (2) the acceptance/non-acceptance of the current situation; (3) sexual pressure related to their marital role; (4) efforts to improve sexual interest or activity. Menopause-related physical changes often (but not always) made sexual interactions difficult. But womens responses to the changes varied. Some used sexual discomfort as a reason to avoid sexual intercourse. Others sought to improve their sexual encounters through behavioural modifications or hormone therapy. CONCLUSIONS Given the variety of reactions to the impact of menopause on sexual behaviour/relationships seen here, it is clear that health professionals need to assess of each womans specific situation and be prepared to recommend a variety of behavioural or hormonal treatment options.

Egg donation compensation: ethical and legal challenges

(unported, v3.0) License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Medicolegal and Bioethics 2014:4 15–24 Medicolegal and Bioethics Dovepress