Cholecystokinin/gastrin receptors in the pancreas of newborn (3-day-old) rats are of type A, as in control mature rats, revealed by pharmacological analysis of specific ' 251-Bolton-Hunter-reagent- day-old rats, 90 -125 kDa in 10-day-old rats and 85 -100 kDa in 14-day-old and 21 -day-old rats, as found in control adult rats. Endo-a-N-acetylglucosaminidase F treatment yielded a core protein of 42 kDa in all developmental stages. These findings are consistent with an age-related postnatal expression of distinct glycoforms of pancreatic cholecystokinin receptors. Furthermore, it was observed that the period 2-3 weeks after birth, characterized by stabilization of the mass of the cholecystokinin receptor, precedes the dramatic increase in the receptor number.Cholecystokinin (CCK) and gastrin are hormonal peptides that share the same C-terminal pentapeptide amino acid sequence [I]. Pancreatic acinar cells from dog and guinea pig have been shown to possess two types of CCK receptor [2 -61. The CCKA receptor type, has a high affinity for CCK, and the pancreatic CCKn or gastrin receptor type has a high affinity for gastrin and poorly discriminates between CCK and gastrin peptides.The existence of specific CCK receptors in term foetus and neonatal rat pancreas was previously documented, although acini or lobules seem to be unresponsive to CCK stimulation near birth [7-91. It was also shown that the capacity of the high-affinity sites on rat pancreatic acini, as well as amylase secretion due to CCK stimulation, gradually increases with
In experiments on old (26 months old) rats, we found that the extracts of Punax ginseng (G115), Ginkgo bilobu (GK501) and their combination Gincosan@ (PHL-00701) administered orally at two doses for 7 days induced changes in the levels of biogenic monoamines in some brain regions (frontal cerebral cortex, hippocampus, striatum, hypothalamus and pons). The most characteristic change was the increase produced by the two extracts and their combination in the serotonin level in all brain structures except for pons compared with controls. In the hippocampus G115, GK501 and their combination decreased the noradrenaline level. The same doses of 6115, GK501 and their combination applied for 7 days to young (3 months old) and old (26 months old) rats caused significant changes in the blood level of prolactin (PRL), growth hormone (GH) and ACTH compared with age-matched controls: both 6115 and GK501 decreased the serum level of PRL compared with age-matched controls; the hormone level being high in old controls, in extract-treated rats it became equal to that in young controls; 6115 and PHL-00701 greatly increased the serum level of ACTH in both age groups compared with age-matched controls. Under conditions of induced immobilization and cold stress in young rats, the 7-day pretreatment with G115, GK501 and their combination led to significant changes in the blood levels of PRL, GH and ACTH compared with control untreated stressed and unstressed rats.
The 7-day oral administration of the extracts from Ginkgo biloba (GK501) and Panax ginseng (G115) as well as their combination PHL-00701 (Gincosan@) produced changes in rat behaviour suggesting memory-enhancing effects. Single doses of agonists and antagonists of different serotonin receptor subtypes influenced the rat's capability for retention of learned behaviour and the behavioural effects of the drugs tested. GK501 decreased the density of 5-HT, receptors in the frontal cerebral cortex and hippocampus. Data concerning the effects of the drugs tested suggest the participation of the serotonergic transmitter system as an important neurochemical correlate of rat behaviour and of the memory effects of the drugs studied. This participation is modulated by the differences in the functions of the serotonin receptor subtypes.
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