Hypothalamic neuropeptides and memory

Abstract

Vasopressin and oxytocin exert pronounced effects on behavior by a direct action on the brain. A single injection of vasopressin results in a long-term inhibition of extinction of a conditioned avoidance response suggesting that vasopressin triggers a long-term effect on the maintenance of a learned response, probably by facilitation of memory processes. In addition vasopressin improves passive avoidance behavior, facilitates retention of sexually motivated T-maze choice behavior in male rats, delays extinction of an appetitive discrimination task, affects approach behavior to an imprinting stimulus in ducklings, delays the postcastration decline in copulatory behavior in male rats, prevents or reverses amnesia induced by electroconvulsive shock, CO2 inhalation, pentylenetetrazol or puromycin. The majority of these effects may be explained by stimulatory influences of vasopressin on memory processes. Generally oxytocin exerts effects which are opposite to those of vasopressin and it has been suggested that oxytocin may be an amnesic neuropeptide. Evidence has been obtained that endogenous vasopressin and oxytocin play a physiological role in brain processes related to memory. Various limbic system structures seem to act as the anatomical substrate for the behavioral effects of vasopressin and different neurotransmitter systems seem to be involved. It is postulated that in case vasopressin affects retrieval processes the site of action is located in the amygdala and the dentate gyrus of the hippocampal complex with dopamine and serotonin as the respective neurotransmitter systems involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible contribution of epigenetic changes in the development of schizophrenia-like behavior in vasopressin-deficient Brattleboro rats

“…Cognitive impairment has drawn attention as particularly important being one of the more treatment resistant components. In the present study cognitive symptoms were studied by NOR and SR, showing that our colony has SCZ-like deficiencies similarly to previous observations [42,58,[62][63][64]. Another negative symptom, the lack of interest to conspecific was confirmed by SA test, which was never used in this strain before, although social impairment was already described in Brattleboro rat [58,65,66].…”

Contrasting effects of vasopressin, desglycinamide-vasopressin and amphetamine on a delayed matching to position task in rats

“…The first result is consistent with the view that AVP has beneficial effects on memory, alleviating the deleterious effects of passage of time on trace strength. This therefore supports the long-standing claim of De Wied and his co-workers (van Wimersma Greidanus et al 1985), that the posterior pituitary peptide has a (central) role in mnemonic processing, which can be demonstrated in appetitively-, as well as aversively-motivated tasks. However, the DGAVP results strongly suggest that AVP's peripheral pressor effects were entirely responsible for its behavioural potency, and this supports the hypothesis elaborated by Le Moal and his co-workers (Le Moal et al 1981;Lebrun et al 1985).…”

“…A substantial body of literature suggests that the posterior pituitary peptide arginineS-vasopressin (AVP) improves mnemonic performance (van Wimersma Greidanus et al 1985). Almost all of the evidence from animal studies has derived from active and passive avoidance tasks.…”

Neuropsychological abnormalities in patients with pituitary tumours

“…Animal data has also suggested a role for the pituitary in memory beginning with De Wied's work (18) showing impairment of avoidance learning and escape behaviour in rats following adenohypophysectomy. This area has been the subject of a number of recent reviews (19)(20)(21)(22). Pituitary hormones, including ACTH and other pro-opiocortin derivatives and vasopressin have been used in man and animals to try to improve memory (23)(24)(25).…”