The time course of noradrenergic pre- and postsynaptic activity during chronic desipramine treatment

The firing of hippocampal cells was studied in rats treated with desipramine 10 mg/kg per day i.p. for various periods of time. These cells were neurophysiologically identified to be noradrenergic postsynaptic by their decreased firing during stimulation of the locus coeruleus (LC). While desipramine given for 1 day produced no change, the drug given for 7, 14, and 21 days produced a 20%, 38% and 89% increase, respectively; only the last increase reached a statistical significance. This time course closely resembles that of the therapeutic action of the drug in depressed patients. Desipramine also altered the firing of norepinephrine-containing cells in the LC. While desipramine given for 1 day produced no change, the drug given for 7, 14 and 21 days produced a 12%, 29% and 34% decrease, respectively; only the last two decrements reached a statistical significance. This time course resembles that of the change in firing of hippocampal cells. Based on this and other data it is suggested that the decrease in the firing of LC cells plays a major role in the increased firing of hippocampal cells obtained after desipramine treatment.

Reported lactose tolerance of members of various racial/ethnic groups in Hawaii and Asia

Subjects from various racial/ethnic groups in Hawaii and homeland Chinese, Japanese, and Koreans reported on their milk drinking in childhood and adulthood, as well as on whether or not milk drinking produced symptoms of intolerance. Intolerance was comparatively infrequent in all groups, although significant differences existed between groups in the frequency with which they manifested symptoms and in discomfort scores. Differences between Hawaiian subjects of Asian ancestry and homeland Asians in the frequency of reported symptoms, in mean discomfort scores, and in amount of milk needed to produce symptoms, as well as the high proportion of symptomatology among Hapa-Haoles (persons of Caucasian and Oriental ancestry) and other data reported herein, are not supportive of the usual genetic explanation of lactose tolerance and are supportive of the belief that dietary practice influences tolerance.

Stimulation of the dorsal noradrenergic dundle and field potentials in the locus coeruleus

Field potentials were recorded from the locus coeruleus following electrical stimulation of the rat midbrain. Activation of a discrete area situated ventrolateral to the central gray evoked long-latency potentials in the locus coeruleus while stimulation of other midbrain sites did not. Damage to this discrete area resulted in a depletion of norepinephrine in the cerebral cortex suggesting that it is a segment of the dorsal noradrenergic bundle arising from the locus coeruleus.

Unit activities in the hypothalamus and midbrain during stimulation of hypothalamic attack sites

Unit activity in the hypothalamus and midbrain of unanesthetized cats was studied during electrical stimulation of the hypothalamus at sites that induced attack and at other comparable sites from which attack was not induced. The changes in the firing of units at distances from 0.7 to 1.9 mm from the site of stimulation were similar to those of units at distances from 2.0 to 5.2 mm. Although stimulation in general affected a majority of units, resulting in increases rather than in decreases of firing rates, and produced similar patterns of unit activity, stimulation at sites that induced attack affected more units, produced a greater change in unit activity and markedly increased firing rates in the lateral hypothalamus and the dorsal part of the midbrain.