ABSTRACT
The effects of new cyclic analogs of ACTH fragments, EHFRWGKPVG-NH2 and KHFRWG-NH2, which have specific and nonspecific active centers in their structure, in the self-stimulation, avoidance, and grooming behavior of rabbits were investigated in this study. The intraventricular administration of EHFRWGKPVG-NH2 in doses of 0.1-2.5 micrograms increased the frequency of self-stimulation (SS), while in doses of 4-5 micrograms, it decreased the frequency of self-stimulation. The administration of KHFRWG-NH2 in doses of 0.1-5.o micrograms, induced a decrease in the frequency of SS by 25-30% in the first 15 min following the injections; this indicator returned to the baseline level thereafter, and decreased again. SS was more intense after 24-48 h, 5-8% higher than the baseline level, and remained practically unchanged over the course of a two-hour experiment. The administration of the EHFRWGKPVG-NH2 fragment in doses of 0.5-2.0 micrograms increased the latent period of the avoidance reaction, decreased the time of the anxiety state, and increased the time of the comfort state. In addition to these changes, both ACTH fragments induced intense grooming, increased the duration of grooming by 200-400% as compared with the control animals which were administered physiological solution.
Subject(s)
Adrenocorticotropic Hormone/pharmacology , Avoidance Learning/drug effects , Grooming/drug effects , Peptide Fragments/pharmacology , Self Stimulation/drug effects , Adrenocorticotropic Hormone/administration & dosage , Amino Acid Sequence , Animals , Chinchilla , Injections, Intraventricular , Male , Molecular Sequence Data , Peptide Fragments/administration & dosage , RabbitsABSTRACT
We studied the influence of new cyclic analogues of ACTH fragments EHFRWGKPVG-NH2 and KHFRVG-NH2 on self-stimulation (SS) and active avoidance (AA) behaviour. Intraventricular injection of EHFRWGKPVG-NH2 in low doses (0.5-2.5 mcg) was shown to increase, that in higher doses (4-5 mcg) to decrease SS frequency. Injection of KHFRWG-NH2 in doses of 0.1-5 mcg resulted in 25-30% decrease of SS frequency during the first 15 min, its subsequent return to the background level and repeated decrease. In 24-48 h SS was 5-8% higher than the background level and practically was unchanged in the course of 2 h of experiment. When testing AA behaviour EHFRWGKPVG-NH2 in doses of 0.5-2 mcg induced twice shorter "anxiety time" and longer latency of AA. Both fragments (0.1-5 mcg) evoked excessive grooming. These effects persisted for 24-72 h. The role of the cyclic analogues of ACTH fragments in the mechanisms of positive and negative reinforcement is discussed.
Subject(s)
Adrenocorticotropic Hormone/pharmacology , Avoidance Learning/drug effects , Grooming/drug effects , Peptide Fragments/pharmacology , Peptides, Cyclic/pharmacology , Self Stimulation/drug effects , Animals , Avoidance Learning/physiology , Dose-Response Relationship, Drug , Electric Stimulation/methods , Grooming/physiology , Hypothalamic Area, Lateral/physiology , Injections, Intraventricular , Male , Rabbits , Reaction Time/drug effects , Reaction Time/physiology , Self Stimulation/physiology , Structure-Activity Relationship , Ventromedial Hypothalamic Nucleus/physiologySubject(s)
Avoidance Learning/drug effects , Extinction, Psychological/drug effects , Vasopressins/pharmacology , 5-Hydroxytryptophan/pharmacology , Animals , Arginine Vasopressin/analogs & derivatives , Arginine Vasopressin/pharmacology , Conditioning, Classical/drug effects , Female , Lypressin/analogs & derivatives , Lypressin/pharmacology , Male , Rats , Terlipressin , Time FactorsABSTRACT
The influence of enkephalin on the processes of elaboration and preservation of the defensive conditioned reflexes of bilateral avoidance (CRBA) and conditioned reflexes of passive avoidance (CRPA) in intact rats and animals with changed functional state of serotoninergic system of the brain has been examined. Injection of enkephalin in dose of 10 mkg to intact animals accelerated the elaboration of CRBA not influencing in this case their preservation, but deeply disturbed the CRPA preservation. The excess of serotonin in the brain created by means of 5-oxytryptophan fully prevented the acceleration of CRBA elaboration by enkephalin under the usual conditions. Injection of enkephalin at the background of serotonin lowering and raising in the brain favoured CRBA preservation. Under the enkephalin influence the inclusion of [3H]tyrosine and [14C]lisine in water-soluble and water-insoluble proteins of different cerebral structures lowered. The obtained data testify to participation of serotoninergic system and brain proteins in the mechanisms of enkephalin action to the processes of learning and memory.
Subject(s)
Avoidance Learning/drug effects , Enkephalins/pharmacology , Memory/drug effects , 5-Hydroxytryptophan/pharmacology , Animals , Brain/drug effects , Conditioning, Classical/drug effects , Escape Reaction/drug effects , Male , Photic Stimulation , Rats , Serotonin/physiologyABSTRACT
Subcutaneous injection of 10 micrograms desglycilargininvasopressin (DG-AVP) does not alter the mean frequency of background unit activity of sensorimotor cortical neurons. However, the pattern of impulse activity is essentially changed. At the same time the reactions of sensorimotor cortical neurons to microiontophoretic administration of acetylcholine and noradrenaline experience definite changes. It is suggested that the DG-AVP-induced changes in chemoreactive properties of neurons underlie the effect of this peptide on the learning and memory.