PubMed Health⌕ Search

Biomedical subjects

C R Almli

Publications and source records attributed to C R Almli.

At least 19 recordsLinked to original sources
PubMed1992

Modulation of lateral hypothalamic activity by olfactory bulb and sciatic stimulation.

Lateral hypothalamic area (LHA) single unit activity (extracellular) was studied in response to electrical stimulation of the olfactory bulb (OB) or sciatic nerve in adult albino rats (n = 39) anesthetized with dialurethane. Olfactory stimulation resulted in a greater proportion of LHA units showing inhibitory rather than excitatory responses, while sciatic nerve stimulation resulted in similar proportions of units showing inhibitory and excitatory responses. Of the 76 LHA units tested with both OB and sciatic nerve stimulation, 36% responded to both stimulation sites, 18% responded only to OB stimulation, 26% responded only to sciatic nerve stimulation, and 20% were unresponsive to either stimulation. The locations of responsive units were diffuse throughout the LHA sampled. The response characteristics of LHA neurons to external sensory stimulation are consistent with the anatomy and putative integrative functions of this brain region.

Action Potentials↗
PubMed1976

Preweanling rats: recovery from lateral hypothalamic damage.

Preweanling male and female albino rats sustained lateral hypothalamic area (LHA) destruction at 10 days of age. Pups with bilateral LHA destruction (Bi-LHA) displayed the lateral hypothalamic recovery syndrome (LHRS) and recovered voluntary feeding and drinking between 44-75 days of age. The Bi-LHA rats of both sexes showed permanent deficits (through 200-275 days of age) in responding to hydrational challenges and did not feed in response to 2-deoxy-D-glucose treatment. Male Bi-LHA rats' body weights were permanently depressed by 20%-25%, whereas female body weight depression was only temporary. Rats sustaining LHA destruction on one side of the brain (Uni-LHA) displayed an abbreviated LHRS, recovering voluntary feeding and drinking by 25-32 days of age. The Uni-LHA rats showed some permanent deficits in responding to hydrational challenges, yet they displayed the same sex differential for body weight regulation as the Bi-LHA rats. The results of this investigation demonstrate nearly identical effects of LHA destruction whether sustained preweaning, postweaning, or during adulthood.

Age Factors↗
PubMedDate not supplied

Evidence for independent osmosensitivity of lateral preoptic and lateral hypothalamic neurons.

The purpose of the present study was to determine if a functional or modulatory relationship exists between osmosensitive neurons of the lateral preoptic (LPO) and lateral hypothalamic (LHA) areas. Unit activity was recorded from one neural area (LPO or LHA) following bilateral destruction of the opposite area, i.e., LPO recording site with LHA lesion site, and vice-versa. Bilateral destruction of the LPO or LHA did not eliminate the osmosensitivity characteristics of LPO or LHA units, demonstrating that units of either area do not require input from the opposite area for osmosensitivity.

Action Potentials↗
PubMedDate not supplied

Infant rats: hypothalamic unit activity.

Single-unit recordings were made from lateral hypothalamic area (LHA) neurons of infant (8 through 21 days of age) male and female albino rats. Basal (or spontaneous) firing rates of LHA neurons were recorded for 20 min from rats 8 through 21 days of age, and mean basal firing rates did not differ across ages. Basal firing rates of LHA neurons in infant rats ranged from less than 1 spike/sec up to 27 spikes/sec, with 56% of the basal rates less than 1 spike/sec. Infant rats also received hypertonic saline injections (and control injections) to determine osmosensitivity characteristics of LHA neurons. Across ages, 56%--88% of LHA neurons were osmosensitive, with the highest percentages of osmosensitive units found in rats 14--21 days of age. Infant rats showed LHA unit electrophysiological characteristics that were quite similar to those obtained from LHA neurons in adult rats with respect to basal firing rates and osmosensitivity, however, LHA neuron activity in infants was not modulated by sensory stimuli as is frequently reported for adults. The results are discussed in terms of functional development of the LHA.

Action Potentials↗
PubMedDate not supplied

Ontogeny of drinking behavior of preweanling rats with lateral preoptic damage.

Male (N = 9) and female (N = 7) infant albino rats sustained bilateral lateral preoptic area (LPO) destruction on the tenth day of life. During development and as adults, these brain-damaged rats were subjected to repeated testing of drinking behaviors in response to cellular and extracellular dehydration. Immediately following LPO destruction the pups ceased suckling and most rats required tube-feeding to maintain life; however, all pups were maintaining body weight through voluntary suckling and/or feeding-drinking by 20-21 days of age. Daily water intakes were elevated from 30-42 days of age, following which intakes decreased to control vonse to water deprivation, polyethylene glycol injection and food deprivation treatments. These results are consistent with the suggestion that the LPO contains osmoreceptors for drinking behavior, and the present results suggest that such osmoreceptors, may be functional by the tenth day of life for rats.

Animals↗
PubMedDate not supplied

Infant rats: sensorimotor ontogeny and effects of substantia nigra destruction.

The ontogeny of sensorimotor behaviors of albino rats were evaluated from birth through adulthood (Experiment 1). Sensorimotor behaviors (e.g., visual and tactile orientation, forelimb and hindlimb hopping, righting reflexes) achieved mature (adultlike) characteristics at various ages during ontogeny and a rostral-caudal developmental pattern was revealed. In Experiment 2, the substantia nigra was bilaterally or unilaterally destroyed in rats at 10 or 25 days of age and the ontogeny of sensorimotor and regulatory (feeding, drinking, body weight regulation) behaviors were evaluated. Bilateral destruction of the substantia nigra, zona compacta, at 10 and 25 days of age resulted in transient cessation of suckling and/or feeding and drinking followed by recovery. Male brain-damaged rats had reduced body weight through 150-170 days of age. Specific feeding and drinking tests revealed the presence of residual regulatory deficits which seemed permanent. Sensorimotor testing revealed transient dysfunction for a variety of sensorimotor behaviors, with eventual recovery of normal sensorimotor capacity. The results are related to sensorimotor ontogeny and recovery from infant brain damage.

Animals↗
PubMedDate not supplied

Effects of septal damage and ovariectomy on feeding, drinking and body weight.

Septal destruction and ovariectomy each influenced food intake and body weight differentially. Animals sustaining septal damage ingested significantly more food than the other groups, and septal hyperphagia persisted for as long as 109 days. Ovarian hyperphagia did not occur under conditions of constant illumination. Septal destruction exerted essentially no effect on body weight, while ovariectomy substantially increased body weight. Sequential surgical manipulations provided further evidence that the ovaries and the septum influence food intake and body weight via independent mechanisms. Results indicated that the septal and ovarian effects on water intake are not mediated via independent mechanisms. Septal and ovarian hyperdipsia were found to be very robust effects occurring regardless of the lighting regimen. It was further demonstrated that ovarian hyperdipsia is not secondary to food intake but rather is primary hyperdipsia.

Animals↗
PubMedDate not supplied

Ontogeny of lateral preoptic unit activity in rats.

Extracellular single unit recordings were made from units within the lateral preoptic area (LPO) of infant rats from 1 day of age through 31 days of age (postweaning). The rats were anesthetized with dial-urethane and basal (spontaneous) spike rates were recorded for 10--20 min. The rats also received pain-arousal stimulation (tail-pinch and sc injection of formalin solution), and osmotic stimulation (sc or ip injection of hyperosmotic NaCl or sucrose solutions). LPO units were spontaneously active in neonatal rats; however, basal spike rates increased during development. Also increasing during development was the percentage of LPO units which displayed alteration of spike rate in response to hyperosmotic injections (osmosensitive). However, LPO units were found that were responsive to severe pain-arousal stimulation at all ages tested. The developmental changes in LPO unit activity characteristics paralleled the morphological development of LPO neurons and the development of osmotically induced drinking behaviors.

Aging↗
PubMedDate not supplied

Effects of intragastric water infusion and gastric distension on hypothalamic neuronal activity.

The effects of gastric water infusion and distension were examined in neurons from various parts of the rat brain. Neurons in the lateral preoptic-lateral hypothalamic-medial forebrain bundle (LPA-LH-MFB) neuropil were sensitive to gastric water infusion and distension. Cells randomly selected and examined in other brain areas were less sensitive to the same stimulation which indicated that the effects were relatively specific. The results, in terms of changes in neuronal discharge frequency from an established baseline, indicate that many cells in the lateral preoptic-lateral hypothalamic-medical forebrain bundle area are affected by intragastric water infusion and gastric distension within a time period during which changes in drinking would normally occur. These neurons were also affected differentially by acute water deprivation. LPA-LH-MFB neurons in 24 hr water deprived animals were significantly more sensitive to water infusions and less sensitive to stomach distension when compared to cells recorded in animals maintained on ad lib eating and drinking. Some of these same neurons were also sensitive to changes in the extracellular concentrations of sodium and glucose. The results are discussed in terms of the involvement of the lateral preoptic-lateral hypothalamic-medial forebrain bundle neuropil in ingestive behavior.

Animals↗