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T H Yin

Publications and source records attributed to T H Yin.

11 recordsLinked to original sources
PubMed1992

Role of locus coeruleus and serotonergic drug actions on schedule-induced polydipsia.

Schedule-induced polydipsia (SIP) poses a general buffering property to reduce the heightened arousal produced by a schedule of intermittent feeding. It thus provides a unique opportunity to study CNS integration in stress-coping reactions. In the present study, we examined the role of the locus coeruleus (LC) and the pharmacological actions of serotonergic (5-HT2) analogs on SIP. Water intake, licking, and bar presses per minute in rats were recorded as indices of SIP activity after they had been subjected to 1-h performance of a fixed-interval 1-min operant pellet conditioning. Our results showed that SIP was progressively decreased after lesions were placed bilaterally in the LC areas and then followed by further lesioning in the bilateral ventral tegmental area. Neurotoxin DSP-4 also had an inhibitory action on the SIP potency. In addition, SIP was attenuated by 2,5-dimethoxy-4-iodoamphetamine (0.1, 0.5, or 1.0 mg/kg, IP), a 5-HT2 agonist, and activated by ritanserin (2.5 mg/kg, IP), a 5-HT2 agonist. After bilateral LC lesions, SIP was attenuated and the activating effect of RIT was abolished. Our data suggest that the LC is involved in the central integration of SIP and that the modulating effects of 5-HT2 receptors on SIP depend upon the integrity of LC function.

Animals↗
PubMed1992

Reduction of blood PO2 decrease and PCO2 increase during asphyxia by paramedian reticular nucleus in cats.

Effects of activation of paramedian reticular nucleus (PRN) on the systemic arterial blood pressure (SAP), heart rate, renal nerve activity (RNA), and changes of the partial pressure of the arterial blood oxygen (PO2) and carbon dioxide (PCO2) during asphyxia were studied in cats anesthetized with chloralose (40 mg/kg) and urethane (400 mg/kg). During a 35-s period of asphyxial anoxia, SAP and RNA increased while heart rate decreased significantly. The arterial blood PO2 decreased by 64.6 +/- 4.7% while the PCO2 increased by 54.6 +/- 6.3%. Electrical stimulation of PRN produced a mild to moderate decrease of the SAP, heart rate, and RNA, but arterial PO2 and PCO2 did not change significantly. When PRN was stimulated simultaneously with asphyxia, increases of SAP and RNA and changes of blood gases subsequent to asphyxia reduced significantly. Arterial PO2 decreased only 54.0 +/- 4.9% while the PCO2 increased 39.4 +/- 10.5% (p < 0.01). Similar effects were observed in the venous blood from inferior vena cava. In addition, when the arteriovenous difference of PO2 and PCO2 was compared, simultaneous PRN stimulation during asphyxia produced a higher PO2 reserve (66.3%) and less PCO2 production (-7%) than without PRN stimulation; PO2 54.2%, PCO2 (-2.9%). The results suggest that PRN is a structure that can exert inhibition over a wide spectrum of body functions; not only autonomic system but probably also metabolism.

Animals↗
PubMed1990

The role of atrial natriuretic factor in dehydration and schedule-induced drinking behaviour.

Dehydration-induced drinking (DID) has been defined as a type of homeostatic behaviour controlled by factors related to water balance, whereas schedule-induced polydipsia (SIP) is considered to be a type of nonhomeostatic drinking subsequent to a general increase in motor excitability. In this study, we have attempted to assess the role of atrial natriuretic factor (ANF) in both models to elucidate the mechanisms controlling water intake. Intracerebroventricular injection of ANF (2-8 nmol) caused a dose related suppression of water intake in both DID and SIP, but intravenous injection with a higher dose of ANF (8 nmol) produced a significant suppression of water intake only in DID. Before drinking started, tissue ANF levels increased in atria in both models and decreased in hypothalamus in DID but not in SIP. After 1 hour of drinking, ANF levels decreased in atria in both models and increased in hypothalamus in SIP but not in DID. These results suggest that DID and SIP are different in their thirst regulation, and that the notion that peripheral ANF serves as a humoral factor sending signals to central in the fluid homeostatic control mechanism is questionable.

Animals↗
PubMed1978

Localization of inhibitory mechanisms to aggressiveness in the medial hypothalamus.

Release of aggressive reactions was studied by placing a small lesion on the medial hypothalamus in the rat with previous massive destruction on the contralateral side of the hypothalamus. A set of tests for reactivity to provocations was applied to rats before the operation, after the unilateral lesion, and once more after the bilateral lesions. Bilateral lesions were accomplished in 53 rats. None of them increased food intake even though the ventromedial region was involved in many cases. Only 7 developed signs of aggressiveness. The unique histological feature of the animals showing aggressiveness was that the lesions were confined to the posterior hypothalamus usually sparing the ventromedial nucleus and were close to the base. It was suggested that the lesions might have interrupted the fibers projecting to the midbrain mechanisms for control of emotional reactivity.

Aggression↗
PubMed1977

Shock avoidance in rats with unilateral lesions in the lateral hypothalamus.

Male albino rats bearing unilateral lateral hypothalamic lesions on either side were tested to acquire active shock avoidance in a two-way shuttle box. The retention of this task learned prior to the surgery was also studied. It was found that the unilateral hypothalamic lesion impaired both performance and no difference between sides was observed.

Animals↗