Cranial puncture, a simple procedure requiring no preparatory surgery: validation by observation of drinking and salt appetite evoked by intracerebroventricular renin

Role of oxytocin and vasopressin in the transitions of weaning in the rat

Sucklings (18-day-old) and weanlings (35-day-old) were injected icv with oxytocin or its antagonist (both 0.5 microg/1 microl), or vasopressin (1.0 ng/1 microl) or its antagonist (100 ng/1 microl), prior to 4-min observation in a behavioral maze with a sibling in one box and their anesthetized dam in the other. Oxytocin abolished nipple attachment in sucklings, decreased time spent with the dam, and increased self-grooming. The oxytocin antagonist had little influence on behavior. Vasopressin increased self-grooming while its antagonist reduced passive contact with the dam, increased active contact with her, and increased exploration and activity. We conclude that these neuropeptides have diverse roles during weaning, maintaining sucklings' behavior or promoting weaning, and subserving the transition from attachment to the dam to independence from her. We propose that these neurochemicals, and others, mediate the neural, affiliative, and affective changes of weaning, and that the term "weaning" should be understood to encompass these behavioral transitions.

Effect of cocaine metabolites on behavior: possible neuroendocrine mechanisms

The predominant cocaine metabolites were tested for central nervous system effects by intracerebroventricular (ICV) administration in rats. We found two types of responses: cocaine, norcocaine (NC), benzoylecgonine (BE), and benzoylnorecgonine (Nor BE) produced stimulatory effects, whereas ecgonine methyl ester (EME) and ecgonine (EC) resulted in no specific effect or sedation. A novel metabolite interaction was revealed when rats were pretreated with EME, which inhibited both analgesia and seizures by subsequently administered cocaine. Pretreatment with EC inhibited both cocaine and BE seizures and seizure-associated death. Direct injection of EME into the nucleus accumbens significantly suppressed systemic cocaine potentiation of intracranial electrical self-stimulation of the ventral tegmental area, whereas corticotropin releasing hormone injected ICV selectively potentiated BE-induced seizures and death. These results confirm multiple, metabolite-mediated activities in the central nervous system. Pharmacological interactions of the metabolites with each other and/or with neurohormones may help explain some of the pathophysiological effects seen in human chronic cocaine abuse.

Effects of benzoylecgonine on the behavior of suckling rats: a preliminary report

A major metabolite of cocaine, benzoylecgonine, causes behavioral activation that progresses to seizures when given intraventricularly to 2-week-old rats. The seizures are characterized by running, hopping, and vocalizing and are mixed with shorter-duration tonic episodes. Pretreatment with haloperidol, at a dose aimed at blocking stereotyped behavior, did not suppress these behaviors. In contrast, seizures were prevented by antiepileptic drugs, with the order of potency being diazepam greater than phenobarbital greater than phenytoin. We hypothesize that the long-lasting cocaine metabolite, benzoylecgonine, contributes to the infant cocaine intoxication syndrome.