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D D Avery

Publications and source records attributed to D D Avery.

31 records · Page 2Linked to original sources
PubMed1972

Thermoregulatory effects of intrahypothalamic injections of adrenergic and cholinergic substances at different environmental temperatures.

1. Rats were unilaterally implanted with chronic indwelling cannulae directed towards the medial preoptic area of the hypothalamus. Carbamylcholine chloride (carbachol), noradrenaline, and saline were microinjected in volumes of 0.5 mul. at each of three environmental temperatures, 5, 24, and 35 degrees C.2. At an ambient temperature of 24 degrees C injections of carbachol significantly raised core temperature, whereas injections of noradrenaline to the same sites significantly lowered temperature.3. Injections of carbachol did not affect core temperature at 35 degrees C, but injections of noradrenaline defended against the normal hyperthermia observed in this environment.4. Hyperthermia resulted from hypothalamic injections of both substances at an ambient temperature of 5 degrees C.5. The data generally support a neurochemical model for hypothalamic thermoregulatory mechanisms proposed by Myers & Yaksh (1969). According to their theory a cholinergically coded heat production pathway courses from the anterior to the posterior hypothalamus. This pathway is activated by 5-HT and inhibited by noradrenaline in the anterior hypothalamus. The observation in the present experiments of hyperthermia following adrenergic stimulation at 5 degrees C cannot be accounted for by this model and therefore an addition to the model is proposed. It is suggested that a heat loss mechanism is also located, at least partially, in the anterior hypothalamus and that this system is inhibited by noradrenaline. Thus a thermal balance is established via an interaction of the two systems.

Animals↗
PubMedDate not supplied

Bombesin: potential integrative peptide for feeding and satiety.

The neuropeptide bombesin (BBS) is examined with regard to possible designation as an integrative peptide. The term integrative peptide has been proposed to distinguish a subset of regulatory peptides. These peptides, distributed in the body and the brain, may function as hormones and neurotransmitters to integrate physiological and psychological functions. It is suggested that BBS may function as a peripheral and central satiety-inducing agent. The specific topics with regard to BBS include: feeding, satiety, and aversion; peripheral and central effects; learning, memory, and reward; route of injection; taste modulation; gastrointestinal activity; neurotransmitter status; mechanism and neuroanatomical site of action; and neural and humoral transmission.

Animals↗
PubMedDate not supplied

Intake of individual macronutrients following IP injections of BBS and CCK in rats.

The effects of injections of either bombesin (BBS) or cholecystokinin octapeptide (CCK-8) on patterns of food intake of macronutrients were examined in adult male rats, and compared to the effects following saline injections. The animals were food deprived for 18 hours and then offered one of three isocaloric dietary components (protein, carbohydrate or fat). During the first 30 minutes following injections of BBS, protein intake was decreased. Suppression of carbohydrate intake, significant between 30 and 60 minutes, was sustained up to two hours following injections. During the first 30 minutes following injections of CCK, animals reduced their intake of each macronutrient. Reductions in the consumption of fat and protein were sustained up to one and six hours, respectively. The availability of particular macronutrients is proposed as a possible factor accounting for differences among studies with respect to self-selection profiles and duration effects.

Analysis of Variance↗
PubMedDate not supplied

Capsaicin does not attenuate bombesin-induced suppression of operant responding for food reward.

Systemic treatment with capsaicin, a neurotoxin which damages unmyelinated peptide-containing sensory neurons, has been shown to attenuate bombesin (BBS)-induced suppression of food intake. To determine whether capsaicin-sensitive fibers mediate the effect of BBS on appetitive motivation, we examined BBS-induced suppression of operant responding in rats pretreated neonatally with capsaicin (50 mg/kg; SC) or control vehicle. At 8-10 weeks of age, rats were trained to bar press for food. After achieving a stable level of performance, the animals were injected with BBS (10 micrograms/kg), normal saline, or prefed with 20 Noyes 45-mg pellets. Animals were then tested in an operant chamber on an FR 5 schedule of reinforcement for one hour. The results indicated that BBS suppressed bar pressing, regardless of whether animals were pretreated with capsaicin or control vehicle. These findings are inconsistent with the hypothesis that BBS induces satiety via capsaicin-sensitive neurons. The results suggest the possibility that more than one mechanism may mediate the effects of BBS: a neural mechanism involved in consummatory responses and a humoral mechanism involved in the operant response.

Animals↗