M.J. Wayner

A simple, direct and rapid method for filling microelectrodes ☆ ☆☆

Abstract A new direct and rapid method for filling single and multibarreled drawn glass capillary microelectrodes is described.

Motor control functions of the lateral hypothalamus and adjunctive behavior

Abstract A theoretical review of some motor control functions of the lateral hypothalamus (LH) as a possible explanation for the stimulus-bound behavior evoked by electrical stimulation of this region of the brain. Relevant data to preference-aversion taste functions mediated by the LH is also considered and related to ethyl alcohol, alcoholism, other adjunctive behaviors and drug addiction in general.

Loss of 2-deoxy-D-glucose induced eating in recovered lateral rats ☆

Abstract Results of the present study demonstrate that rats which have recovered in a typical manner from lateral hypothalamic (LH) lesions and do not drink following subcutaneous injection of hypertonic saline do not eat in response to intraperitoneal injection of 2-deoxy-D-glucose (2-DG), 600 mg/kg and 750 mg/kg, and also confirm the earlier work of others that they do not eat in response to the administration of insulin, 8 units. Another group of rats which recovered from the LH lesions more rapidly and drank following the administration of hypertonic saline and insulin did not eat following insulin and did not eat or drink following the two doses of 2-DG. Therefore, although the LH is necessary for insulin and 2-DG induced drinking and eating, separate structures seem to be involved in the mediation of drinking and eating.

A new factor affecting the consumption of ethyl alcohol and other sapid fluids

Abstract In an attempt to explain the fact that we were unable to repeat the results of previous experiments on lateral hypothalamic electrical stimulation induced ethanol consumption, we discovered that the apparent change in preference-aversion might be due to brief periods of withdrawal of one of the solutions or the presentation of the ethanol solutions to the animals only on every other day. Results of five experiments are presented. Prolonged exposure to ethanol resulted in unpredictable periodic increases and a more gradual increase in the ethanol consumption of most of the animals studied. Many of the increases occurred with relatively high concentrations of ethanol which the animals had avoided previously. Increased consumption of ethanol occurred in some animals very rapidly following the periodic presentation and withholding of ethanol solutions for two days every other two days. The effect was not specific to ethyl alcohol and occurred with dilute solutions of quinine monohydrochloride and 0.05% o-benzoic sulfimide (saccharin). As a similar effect was observed during four 24 hr food deprivation periods every other day in two out of six animals and in three animals with 24 hr water deprivation every other day, a possible explanation in terms of the lateral hypothalamus and general arousal was discussed. In addition, the specificity of the alcohol deprivation effect was not confirmed as it was shown to occur in this study with a 0.05% saccharin solution. Also, the results reported here indicate that whether or not lateral hypothalamic electrical stimulation alone is a sufficient condition to enhance the consumption of ethanol has not been determined adequately.

Specificity of behavioral regulation

Abstract A critical review of some relevant data concerning water deprivation induced drinking, water and food deprivation induced drinking, food associated ad lib drinking, salt arousal of drinking, peripheral modulation of deprivation induced drinking and a discussion of the similarities to adjunctive drinking are presented. The specificity of the physiological basis of drinking is questioned and the role of environmental stimuli and orogastric stimulation in the elicitation and maintenance of licking is emphasized. Some unique properties of a lateral preoptic-lateral hypothalamic-brainstem motor control system are described and suggested as a possible mechanism for adjunctive behavior. The generality and significance of schedule induced polydipsia as a function of this system was demonstrated.

Afferent connections to the lateral hypothalamus: A horseradish peroxidase study in the rat ☆

Horseradish peroxidase, 13% Sigma Type VI, was administered iontophoretically to the mid lateral hypothalamus (LH) of male hooded rats. Animals were perfused intracardially on the following day and brains were removed and sliced in the coronal or sagittal planes into 30-50 micrometer sections. Sections were processed with DAB and BDH for the brown and blue reaction products and later examined by bright and dark field microscopy for the presence and location of retrogradely labeled neurons. Results indicate that a significant number of afferent connections to the LH originate in the olfactory and accumbens nuclei, pyriform cortex, olfactory tracts, magnocellular and medial preoptic and anterior hypothalamic regions, stria terminalis, stria hypothalamic tract, diagonal tract of Broca, caudate-putamen and globus pallidus, internal capsule, lateral septal nuclei, lateral preoptic area and anterior medial forebrain bundle, the various amygdaloid nuclei, zona incerta, perifornical region, dorsal and ventral medial hypothalamic areas, supraoptic, paraventricular and periventricular nuclei, posterior hypothalamus and medial forebrain bundle, ventral thalamic nuclei, the fields of Forel, arcuate and mammillary nuclei, adjacent to the fasciculus retroflexus, in the ventral tegmental area of Tsai, interpeduncular nucleus, substantia nigra, mesencephalic reticular formation, periaqueductal gray, locus coeruleus and parabrachial region. Results are discussed in terms of previous anatomical and neurophysiological data, probable pathways, and the function of LH neurons.

Effects of angiotensin II on central neurons.

Abstract Effects of angiotensin II administered intravenously and by means of electrophoresis through multibarrel micropipette electrodes on the frequency of extracellularly recorded action potentials of brain cells were determined. A total of 293 neurons in seven different parts of the brains of male and female hooded rats anesthetized with urethan or a mixture of urethan and chloralose were tested. Results indicate that angiotensin affects many different cells within the lateral hypothalmus, zona incerta, ventromedial and dorsomedial hypothalamic nuclei, dentate gyrus and thalamus. The cells of the LH and zona incerta are the most sensitive to angiotensin and two types of lateral hypothalamic neurons were found which were affected differently by angiotensin and stimulation of the basolateral amygdaloid nucleus. Some of the Na sensitive neurons, all of which were sensitive to angiotensin, displayed a very pronounced potentiation of discharge frequency when angiotensin and Na were administered simultaneously. Angiotensin II might therefore influence drinking because of a relatively low threshold effect on hypothalamic neurons.

Effects of various periods of food deprivation on serotonin synthesis in the lateral hypothalamus.

One hr following an infusion of 3H-L-tryptophan, the lateral hypothalamus was perfused with physiological bacteriostatic saline for 40 min. Samples of perfusate, which corresponded to 75--90 min post-infusion, were analyzed by thin layer chromatography for estimation of 3H-labelled L-tryptophan, 5-hydroxytryptophan and 5-hydroxytryptamine. The results indicate that tryptophan uptake and serotonin synthesis are enhanced as a function of hours of food deprivation.

Effects of ethyl alcohol on central neurons

A method was developed for the electrophoretic application of ethyl alcohol through one capillary in a multibarrel microelectrode array in the vicinity of the recording electode. Effects of ethyl alcohol and angiotensin II applied by means of electrophoretic ejection and ethanol administered intravenously on the frequency of extracellularly recorded action potentials of brain cells were determined. A total of 87 neurons in four different parts of the brain in female hooded rats anesthetized with a mixture of urethan and chloralose were tested. Results reveal that a most sensitive neurons appear to be those of the lateral hypothalamus within the medial forebrain bundle. Cells of the zona incerta and thalamus were also sensitive to ethanol. Cells of the cerebral cortex appear to be relatively less sensitive. Many of the ethanol sensitive cells also responded to angiotensin II and when tested the effects were potentiated by Na.

Effects of hypothalamic stimulation, acclimation and periodic withdrawal on ethanol consumption

Abstract The effects of electrical stimulation of the lateral hypothalamus (LH) on subsequent consumption of previously determined aversive ethanol solutions was studied. Previously published methods were employed in order to determine the possible contribution to the increased consumption produced by the presentation of the ethanol solutions every other day. This mode of presentation has been referred to as periodic withdrawal. Results indicate that electrical stimulation of the LH produces an immediate but small enhancement of ethanol consumption (1.0 g/kg per day); whereas, the periodic withdrawal of acclimated ethanol solutions is much more powerful and results in an increased consumption of approximately 4.0 g/kg per day over the same period of time. A pronounced increase in consumption appears after the second period of withdrawal.