Learned histamine release.

Most of the effort directed at understanding the problems of allergy has focused on the interacting components of the immune system. The possibility that histamine may be released as a learned response has now been tested. In a classical conditioning procedure in which an immunologic challenge was paired with the presentation of an odor, guinea pigs showed a plasma histamine increase when presented with the odor alone. This suggests that the immune response can be enhanced through activity of the central nervous system.

Long day lengths increase brain weight and DNA content in the meadow vole, Microtus pennsylvanicus.

Male voles reared in long (spring) day lengths had heavier brains with greater total DNA content than did males housed in short (fall) day lengths; these effects were not observed in female littermates kept in the two photoperiods. Male brains were heavier than female brains in long but not in short photoperiods. Day length affected brain mass during early postnatal development, but not when treatments were initiated in adulthood. Seasonal differences in brain development, including the numbers of neurons and glia, may reflect different metabolic and behavioral demands faced by males born in spring and fall, respectively.

Cocaine exposure prebreeding to weaning: maternal and offspring effects.

In a model emphasizing prebreeding cocaine administration, rats exposed to cocaine (50 mg/kg) daily were compared to saline-injected and noninjected controls with respect to weight changes, food and water intake, maternal behavior, offspring weight, and activity. During the first 21 days cocaine-treated dams lost weight, while the control dams gained. Throughout gestation and the first 14 days of lactation all groups gained weight, but the cocaine-exposed dams never completely recovered from the initial anorectic effect. Except during the first week of exposure, cocaine dams ate and drank more than the normal controls and drank more than the saline group. During gestation there was no difference in food intake, although the cocaine dams continued to drink more than controls. During lactation there were no differences in food and water consumption across groups. However, the cocaine dams exhibited more nursing behavior. From birth to day 21, the offspring of cocaine-treated dams were smaller than those of either control group. By 51 days of age, group differences had disappeared. Cocaine-exposed pups and saline offspring tested at days 28 and 85 were more active than those of noninjected controls. The results indicate that administration of cocaine for a period prior to breeding and during gestation and lactation, a protocol which closely resembles human drug abuse patterns, is more devastating than the administration during gestation.

Sex differences and asymmetries of catecholamines: relation to turning preferences.

Male and female Sprague-Dawley rats were tested for turning preferences in a multiple alley maze. The left and right caudate-putamen were dissected and assayed for norepinephrine and dopamine. Dopamine was not found to be lateralized contralateral to turning preference for females as a group. However, dopamine was significantly lateralized contralateral to the females turning preference if a strong turning bias was present. No relationship between dopamine asymmetry and turning preference was evident for males. Females were found to have norepinephrine significantly lateralized to the left caudate-putamen; in males greater striatal norepinephrine levels were equally distributed between left and right sides. This sexual dimorphism in norepinephrine lateralization was not related to turning preference.