ABSTRACT
We studied the effects of tactivin and splenic polypeptides on learning and memory of thymectomized animals. In 3-week rats, thymectomy blocked active avoidance conditioning. Injections of tactivin (0.5 mg/kg) during 1 month after surgery restored learning capacity; splenic polypeptides were ineffective.
Subject(s)
Avoidance Learning/drug effects , Memory/drug effects , Nootropic Agents/pharmacology , Peptides/pharmacology , Thymectomy , Thymus Extracts/pharmacology , Thymus Gland/chemistry , Animals , Avoidance Learning/physiology , Conditioning, Classical/physiology , Memory/physiology , Nootropic Agents/isolation & purification , Organ Specificity , Peptides/isolation & purification , Rats , Rats, Wistar , Spleen/chemistry , Thymus Extracts/isolation & purification , Thymus Gland/physiology , Thymus Gland/surgeryABSTRACT
OBJECTIVE: Our aim was to investigate the influence of thymic polypeptides on pain sensitivity and to analyze a possible role of the opioid system in the implementation of the analgesia caused by immobilization stress. METHODS: The study was performed on male Wistar rats at the Moscow state University named after M. V. Lomonosov. We studied effects of thymus peptides: thymuline (0.15 mg/kg), fraction 5 thymosin (0.25 microgram/kg) and cattle thymus extracted product (CTEP) (0.5 mg/kg) on pain sensitivity in rats using test "tail flick" without stress, with acute (3 h) and sub acute (12 h) immobilization stress. The comparison groups were animals treated with saline and spleen polypeptides. RESULTS: It is shown that preparations of thymus increase the threshold of pain sensitivity in the intact animals. Immobilization stress duration 3 and 12 h in thymus peptides treated rats caused a less pronounced increase in pain threshold than in the control groups (immobilization stress 3 h: CTEP--p = 0.025, thymuline--p = 0.022, fraction 5 thymosin--p = 0.033; immobilization stress 12 h: CTEP--p = 0.034, thymuline--p = 0.027, fraction 5 thymosin--p = 0.036). The opioid receptor blocker naloxone (1 mg/kg) did not completely block the stress-induced analgesia, indicating the presence of both opioid and non -opioid components in this state. In thymus peptides treated rats, opioid component was less pronounced than in the control groups (CTEP--p = 0.031, thymuline--p = 0.026, fraction 5 thymosin--p = 0.029). CONCLUSION: Pre-activation of the opioid system by the thymus polypeptides leads to an increase in the share of non-opioid component of the stress-induced analgesia and prevents the depletion of the opioid system in immobilization stress.
Subject(s)
Naloxone/pharmacology , Pain , Restraint, Physical/adverse effects , Thymic Factor, Circulating , Thymosin , Thymus Gland/metabolism , Analgesia/methods , Animals , Cattle , Male , Models, Animal , Narcotic Antagonists/pharmacology , Pain/diagnosis , Pain/drug therapy , Pain/etiology , Pain/metabolism , Pain/physiopathology , Pain Management , Rats , Rats, Wistar , Receptors, Opioid/metabolism , Thymic Factor, Circulating/metabolism , Thymic Factor, Circulating/pharmacology , Thymosin/metabolism , Thymosin/pharmacology , Thymus Extracts/metabolism , Thymus Extracts/pharmacologyABSTRACT
Experiments on Wistar rats showed that thymic peptides produce a stress-protective effect that manifested in prevention of functional impairment of conditioned active avoidance response and a decrease in generalized motor activity typical of higher nervous activity failure. We concluded that thymic peptides significantly modulate integrative functions of the brain and produce a stress-protective effect.
Subject(s)
Avoidance Learning/drug effects , Brain/drug effects , Peptides/pharmacology , Stress, Physiological/drug effects , Animals , Rats , Rats, WistarSubject(s)
Analgesics/pharmacology , Avoidance Learning/drug effects , Peptides/pharmacology , Receptors, Opioid/metabolism , Thymus Extracts/pharmacology , Adjuvants, Immunologic/pharmacology , Animals , Male , Naloxone/pharmacology , Narcotic Antagonists/pharmacology , Rats , Rats, Wistar , Receptors, Opioid/agonistsABSTRACT
Apart from restoration of disordered immunological parameters, tactivin and derinat exhibit a pronounced effect on the higher integrative functions of the brain. Experiments on Wistar rats have shown that these drugs accelerated conditioning of food and defense responses. New methods for quantitative evaluation of memory trace consolidation are proposed.
Subject(s)
Immunologic Factors/pharmacology , Learning/drug effects , Memory/drug effects , Animals , Brain/drug effects , Brain/physiology , DNA/pharmacology , Male , Peptides/pharmacology , Rats , Rats, Wistar , Thymus Extracts/pharmacologyABSTRACT
Experiments on outbred albino rats showed that tactivin (thymic polypeptide preparation) reduced functional disturbances in active avoidance reaction induced by extra electric current exposure violating the established relationships between the stimuli, reaction, and its result. The preparation provided high level of avoidance reaction after its violation. New effects of immunocorrective agent tactivin were detected. It not only restored the disordered immunological parameters, but also exhibited a pronounced effect on the higher integrative functions of the brain and produced an antistress effect.
