Mary Anne Della-Fera

Differential distributions of cholecystokinin in hamster and rat forebrain

Rats and golden hamsters show a differential feeding response to intracranial injections of cholecystokinin (CCK). Rats, but not hamsters reduce food intake after CCK injections into the hypothalamic paraventricular nucleus. In view of this species difference, we undertook an immunohistochemical study of the distribution of CCK-immunoreactivity in the hamster hypothalamus and remaining forebrain. CCK-immunoreactive perikarya were abundant in the neocortex, claustrum, hippocampal formation, amygdaloid complex, bed nucleus of the stria terminalis, nucleus of the lateral olfactory tract and in the magnocellular basal nucleus. CCK-immunoreactive neurons had a more restricted distribution in the diencephalon and were relatively rare in the preoptic area-hypothalamus. The only exception was the suprachiasmatic nucleus and adjacent medial anterior hypothalamus, in which CCK-immunoreactive neurons were numerous. CCK-containing perikarya were not observed in the hamster hypothalamic paraventricular and supraoptic nuclei, where they have been reported to occur in the rat. Groups of CCK-positive perikarya were also noted in the hamster thalamic paratenial and parafascicular nuclei. CCK-immunoreactive fibers/terminals were localized in the caudate and putamen, periventricular zones, dorsolateral geniculate, thalamic reticular nucleus and the superficial layer of the optic tectum. Fiber/terminal labeling was also present in those regions associated with CCK-immunoreactive perikarya. Our results indicate that the telencephalic distribution of CCK-containing neurons in the hamster appears to be similar to that reported in the rat. However, several differences occur in the diencephalon. Perhaps the most striking is that the hamster differs from the rat in having a large group of CCK-containing neurons in the suprachiasmatic nucleus, and in lacking the CCK-containing perikarya observed in the rat paraventricular and supraoptic nuclei. These differences may underly species differences in feeding responses to intracranial CCK injections and gonadal responses to short photoperiods. Our data further suggest that the distribution of neuropeptides and other neuroactive substances may not always be conserved during evolution.

Rumination: Its significance in adults with bulimia nervosa

Abstract Rumination in infants and young children has been described extensively in the literature. More recently, reports have appeared on rumination in adults in association with bulimia nervosa, but not with anorexia nervosa. The authors describe two cases in which rumination could have been easily overlooked had a line of questioning not been pursued that facilitated establishment of the diagnosis. The significance of the association of rumination with bulimia nervosa, and the possible complications, are further discussed.

Cholecystokinin concentration in specific brain areas of rats fed during the light or dark phase of the circadian cycle

Measurement of peptide concentration in specific areas can be used as an initial investigative method for identifying brain sites in which the peptides may be acting. In this study cholecystokinin (CCK) concentration in specific hypothalamic and hindbrain areas of male Sprague-Dawley rats was measured in order to determine whether changes occurred as a result of feeding activity during different portions of the circadian cycle. Three groups of 40 rats each were studied: Group 1 were fasted 16 hr during the dark phase then sacrificed immediately or after a 20 min light phase meal. Group 2 were fasted 16 hr during the light phase then sacrificed immediately after lights out or after a 20 min dark-onset meal. Group 3 were fed ad lib and sacrificed immediately after light out or after a 20 min dark-onset meal. CCK was extracted from dissected areas and concentration was measured by RIA. There was no difference in CCK concentration of any of the 9 brain areas in rats fasted during the dark phase and fed during the light phase. In rats fasted during the light phase CCK concentration of the paraventricular nucleus (PVN) was greater in those that subsequently ate a meal at dark-onset than in those that did not eat (p less than 0.05). In ad lib fed rats CCK concentration was less in the anterior hypothalamus (AH) and greater in the supraoptic nucleus (SON) in rats that ate a dark-onset meal than in rats that did not (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Medial hypothalamic lesions in Syrian hamsters: Characterization of hyperphagia and weight gain ☆

Syrian golden hamsters (Mesocricetus auratus) received bilateral lesions aimed at the ventromedial hypothalamus (VMH) or a sham lesion. In the first study, some of the animals in each surgical group were housed in standard sedentary conditions while others had free access to running wheels. The lesions produced a 30% increase in the daily intake of chow, and this was accomplished exclusively by increased meal sizes. As a result, lesioned hamsters gained body weight relative to controls both on the chow diet and in a subsequent high fat diet phase. The effects were comparable in both sedentary and exercising groups. The lesions produced increases in body length and fat content. In the second study, lesions were made in the VMH or in adjacent nuclei and, after an initial period on chow, the hamsters were then given a choice between chow and high fat diet. The lesioned hamsters showed no unusual preference for the high fat diet but, as before, those with damage to the VMH or paraventricular nucleus (PVN) showed exaggerated body weight gain. Hamsters with these lesions were hyperinsulinemic in both fed and fasted conditions at the end of the study.

Intestinal infusion of a liquid diet alters CCK and NPY concentrations in specific brain areas of rats.

Cholecystokinin (CCK) and neuropeptide Y (NPY) have been implicated in the control of food intake in a number of species. This study was carried out to determine 1) whether nutrient-related stimulation of the upper small intestine could activate central CCK and NPY neuronal systems, resulting in changes in concentration of these peptides in specific brain areas, and 2) the influence of the circadian cycle on nutrient-related effects. Four groups of rats received treatments of either 1.0 ml saline (S) or Ensure liquid diet (E) infused into the duodenum either during the dark (D) or light (L) phase of the circadian cycle. CCK and NPY concentrations in extracts of specific brain areas were measured by RIAs. CCK concentration in the supraoptic n. (SON) was higher in D than in L, regardless of infusion treatment, and in the dorsal parabrachial n. area (DPN), CCK concentration was higher in E than S infused rats, regardless of circadian phase. CCK concentration in the dorsal motor vagal n. area (DMV) was higher in E, but only during L. NPY concentration was higher in DPN and paraventricular n. areas (PVN) and lower in the suprachiasmatic n. area (SC) after E, regardless of circadian phase. The changes in concentration of CCK and NPY in specific brain areas in response to food in the upper intestine suggest that nutrient-related signals from the intestine can activate specific CNS CCK and NPY-containing neural pathways.

Clonidine has a bidirectional effect on operant responding for food.

Clonidine, an alpha-noradrenergic agonist, has had inconsistent effects when administered peripherally in previous studies of feeding behavior. The present experiment was undertaken to evaluate clonidine using an operant feeding paradigm (continuous reinforcement schedule) to provide detailed data on the time course of its effects. Over an entire four-hour session, all doses of clonidine tested (25, 50, or 100 micrograms/kg) increased bar-pressing. The 50 micrograms/kg dose was most effective. An examination of the time course of responding revealed that the initial effect of clonidine was to decrease responses with the duration and magnitude of the decrease directly proportional to dose. However, clonidine also prolonged a phase of steady responding for food once the animals resumed bar-pressing, resulting in a net increase of food intake. Future investigations of clonidine should take into account the effects of increasing dose on delayed onset of feeding.