Biomedical subjects

C Marinescu

Publications and source records attributed to C Marinescu.

11 recordsLinked to original sources

PubMed1986

Hypothalamic serotonin in the control of meal patterns and macronutrient selection.

Serotonin (5-HT) is believed to have an inhibitory influence over feeding behavior. The present experiments were designed to investigate the effects of hypothalamic 5-HT on spontaneously motivated feeding and appetite regulation. Freely-feeding rats were injected with 5-HT or norfenfluramine (NORFENF) directly into the paraventricular hypothalamus (PVN), and precise changes in feeding behavior were monitored by a computer. Following PVN 5-HT or NORFENF injection, animals exhibited a marked suppression in food intake, associated with a decrease in meal size, duration and eating rate, and no change in the frequency of meals consumed. This suggests that brain 5-HT may influence primarily the induction of satiety rather than the suppression of hunger. The effect of drugs presumed to affect brain 5-HT transmission on diet selection was also investigated in groups of rats injected centrally with 5-HT or NORFENF or peripherally with either fenfluramine, quipazine or cyproheptadine. In a series of 2-diet tests, rats centrally injected with 5-HT or NORFENF exhibited a selective suppression of the carbohydrate-rich diets. In animals provided with three pure macronutrient diets, protein, carbohydrate, and fat, systemic administration of serotonergic agents had its greatest impact on fat and carbohydrate ingestion, as compared to protein consumption. These findings support a role for hypothalamic 5-HT in modulating meal patterns and appetite for particular macronutrients.

Animals↗

PubMed1985

Role of hypothalamic norepinephrine in control of meal patterns.

Feeding behavior has been shown to be strongly affected by central administration of catecholamines. In this study, we examined in freely-feeding rats the effect of hypothalamic norepinephrine (NE) injections on the basic parameters of spontaneous ingestion. Precise changes in feeding behavior in rats maintained on ad lib food and water intake were monitored by a PDP 8 computer connected to an apparatus capable of measuring licks and bites of food. Injections of NE were administered into the hypothalamic paraventricular nucleus, the most sensitive brain area for the elicitation of feeding through direct alpha-noradrenergic stimulation. In tests conducted under both light and dark conditions, NE facilitated food intake, primarily by an increase in meal size rather than meal frequency. The first meal after injection was increased in size and duration; the rate of eating was also enhanced. Whereas the following intermeal interval was significantly larger, subsequent meals and intermeal intervals appeared generally unaffected. This evidence is consistent with the proposal of a role for hypothalamic NE in the maintenance, rather than initiation, of feeding behavior in freely-feeding rats.

Animals↗

PubMed1984

Chronic infusion of norepinephrine and clonidine into the hypothalamic paraventricular nucleus.

Previous experiments have shown that acute injection of NE and CLON into the PVN initiates a short-term feeding response in satiated rats. This study examined, in brain-cannulated rats, the impact of remote, chronic injections of NE, CLON, or saline on daily food intake and body weight gain. Over a period of 14 days, NE was infused into the PVN, either continuously at a rate of 12 nm/microliter/hr, or discretely at a rate of 6 nm/microliter/sec. In addition, the alpha 2-adrenergic agonist CLON was infused into the PVN discretely at a rate of 3 nm/0.5 microliter/30 sec. Relative to saline infusion, chronic (continuous or discrete) stimulation of the PVN with either of these drugs was effective in potentiating daily food intake by 12-19% and in increasing body weight gain, from approximately 1.5 g/day to 3.3 g/day. This evidence indicates that medial hypothalamic NE, especially within the PVN, is sufficiently robust to alter long-term feeding patterns and body weight regulation.

Animals↗

PubMed1969