Search PubMed⌕ Search

Biomedical subjects

H Moltz

Publications and source records attributed to H Moltz.

At least 19 recordsLinked to original sources
PubMed1993

Fever: causes and consequences.

The present review distinguishes pathogenic, neurogenic, and psychogenic fever, but focuses largely on pathogenic fever, the hallmark of infectious disease. The data presented show that a complex cascade of events underlies pathogenic fever, which in broad outline - and with frank disregard of contradictory data - can be described as follows. An invading microorganism releases endotoxin that stimulates macrophages to synthesize a variety of pyrogenic compounds called cytokines. Carried in blood, these cytokines reach the perivascular spaces of the organum vasculosum laminae terminalis (OVLT) and other regions near the brain where they promote the synthesis and release of prostaglandin (PGE2). This prostaglandin then penetrates the blood-brain barrier to evoke the autonomic and behavioral responses characteristic of fever. But then once expressed, fever does not continue unchecked; endogenous antipyretics likely act on the septum to limit the rise in body temperature. The present review also examines fever-resistance in neonates, the blunting of fever in the aged, and the behaviorally induced rise in body temperature following infection in ectotherms. And finally it takes up the question of whether fever enhances immune responsiveness, and through such enhancement contributes to host survival.

Animals↗
PubMed1990

E-series prostaglandins and arginine vasopressin in the modulation of male sexual behavior.

Studies carried out recently in the author's laboratory have suggested that fever accompanies copulation in the male rat. Given the action of prostaglandin-E (PGE) in the genesis of fever and given the integrative role of the medial preoptic area (MPOA) in the expression of both fever and male sexual behavior, two hypotheses were advanced concerning male copulation. The first concerns PGE in facilitating transmission in MPOA pathways mediating mounting, intromission and ejaculation. The second concerns arginine vasopressin, a presumed "natural antagonist" of PGE, in inhibiting such transmission and eventually making the male refractory to the receptive female. Several experiments were suggested for testing each hypothesis.

Animals↗
PubMed1989

Pheromonal emission by pregnant rats protects against infanticide by nulliparous conspecifics.

The present studies of experiments focuses on infanticide in the nulliparous rat and asks two questions. First, what do infanticidal nulliparae gain from killing unrelated young? And second, does the recently parturient female have an effective strategy to counter female infanticide? With regard to the first question, we show two benefits from killing unrelated young, namely, that the killer utilizes the young as a food resource and that she occupies the nest site of the mother whose young she has destroyed. With regard to the second question, we show that an extended period of cohabitation with a pregnant female reduces the incidence of infanticidal behavior in nulliparae. Additionally, we demonstrate that the mother emits a pheromone during pregnancy which in itself reduces the incidence of infanticide and, in fact, often makes potentially infanticidal females maternal. The possible endocrine basis of this induced maternal behavior is discussed.

Animals↗
PubMed1988

Infanticide in the male rat: the role of the vomeronasal organ.

The present study constitutes the first demonstration that vomeronasal chemoreception plays a role in the response of the virgin male rat to conspecific newborn. Specifically, it shows that virgin males, after removal of the vomeronasal organ, exhibit a decrease in the incidence of infanticidal behavior. This finding is discussed in terms of how responsiveness to young can be affected by changes in the accessory olfactory system.

Aggression↗
PubMed1988

How the nose cools the brain during copulation in the male rat.

Copulation in the male rat is accompanied by a progressive increase in both body temperature and hypothalamic temperature and, soon after ejaculation, by a rapid and selective decrease in hypothalamic temperature. We hypothesized that two changes occur in tandem within the vasculature of the nasal mucosa that contribute, respectively, to hypothalamic heating and hypothalamic cooling. The first takes place prior to ejaculation and involves mucosal vasoconstriction and warm venous blood flowing from the nose to the base of the brain. We thought of such warm blood as retarding heat loss from the hypothalamus. The second takes place immediately following ejaculation and involves the same venous blood, but now cool owing to an abrupt dilation of nasal blood vessels. We hypothesized that such cool venous blood is largely responsible for the observed postejaculatory reduction in hypothalamic temperature. To test our hypothesis, we measured temperature at the surface of the nasal mucosa and in the hypothalamus during successive copulatory bouts. In accord with prediction, we found a reduction in mucosal-surface temperature prior to ejaculation (reflecting vasoconstriction and heat retention) and a substantial rise in mucosal-surface temperature following ejaculation (reflecting vasodilation and heat dissipation). Accompanying these changes in nasal vasomotor tone was a progressive preejaculatory rise in hypothalamic temperature and a rapid postejaculatory decrease. We conclude that nasal venous blood modulates the temperature of the ventral brain through conductive heat exchange and that such heat exchange is conspicuous during sexual behavior.

Animals↗
PubMed1988

Infanticide in rats: male strategy and female counter-strategy.

The present series of experiments addresses the question of whether mating governs infanticide in the male rat and, in addition, asks whether the female rat has available an effective counter-strategy to male infanticide. With regard to the first question, we found that mating provides a safeguard against the killing of own young. That is, mating induces a general inhibition of infanticide coincident with the birth of the male's young and a recrudescence of infanticide synchronized with their weaning. The particular gain realized in killing alien young depends on the age of young and consequently on whether the mother had reached postpartum estrus. We also found that the pregnant female has an effective strategy to counter male infanticide which she employs before the young are born. The data show that this counter-strategy involves the synthesis of a chemosignal of low volatility emitted during pregnancy. The possible role of the male's vomeronasal system in the reception of this chemosignal is discussed.

Aggression↗
PubMed1987

Hypothalamic temperature and the 22 kHz vocalization of the male rat.

Following ejaculation the male rat emits a 22 kHz vocalization that has been hypothesized to play a communicative role. We found previously that this vocalization is often accompanied by rapid and selective hypothalamic cooling, and we hypothesized that the vocalization or, more precisely, the thoracic-laryngeal maneuver underlying the vocalization, is primarily a thermoregulatory behavior. Accordingly, one prediction made herein was that heating the brain of the isolated male, through the infusion of prostaglandin E2, would be accompanied by the vocalization. Another was that cooling the brain of the copulating male through the injection of sodium salicylate would significantly reduce the post-ejaculatory vocalization. Both predictions were confirmed.

Animals↗
PubMed1987

Hypothalamic temperature and deep body temperature during copulation in the male rat.

The medial preoptic area (MPOA) of the hypothalamus is involved in both the expression of male sexual behavior and the regulation of physiological temperature. This duality of function led us to ask whether arousal, intromission, and ejaculation are accompanied by a distinctive temperature profile. Using telemetric thermosensors, we monitored MPOA temperature and deep body temperature during copulation in the male rat. Changes in MPOA temperature were highly uniform, more so than changes in body temperature. The MPOA heated prior to ejaculation, cooled rapidly following ejaculation and then began to heat again coincident with the termination of the post-ejaculatory refractory period. These changes could not be related to variations in general activity. The most striking change in MPOA temperature, rapid cooling following ejaculation, was explained in terms of certain behaviorally-induced hemodynamic events.

Animals↗
PubMed1986

Sexual behavior in the female rat following removal of the vomeronasal organ.

We used female Wistar rats from which the vomeronasal organ (VNO) has been removed. The first question addressed was whether such females would show deficits in sexual behavior. The data left no doubt that removal of the VNO severely depressed lordosis as well as such proceptive behaviors as "darting" and "hopping." We then injected estrogen and progesterone and, in still another experiment, estrogen and luteinizing hormone-releasing hormone (LHRH). Estrogen and progesterone significantly enhanced lordosis, but only estrogen and LHRH raised the lordosis quotient of VNO-ablated females to that of the control females. We discuss the results in terms of a theoretical model involving the complementary action of estrogen and LHRH in inducing lordosis in the intact female.

Animals↗
PubMed1986

Copulatory behavior of sexually naive and sexually experienced male rats following removal of the vomeronasal organ.

The question addressed was whether removal of the vomeronasal organ (VNO) of the male rat would produce observable deficits in sexual behavior. Both sexually naive and sexually experienced males were used and each animal was given more than 12 hours to mate with a receptive female. Although sexual arousal was depressed in both groups, and depressed more among naive than experienced animals, every male was eventually aroused by the receptive female and eventually ejaculated. We conclude that while the VNO contributes to arousal it is not indispensable for arousal.

Animals↗
PubMed1985

Prolonged responsiveness to the maternal pheromone in the postweanling rat.

When rat young reach 27 days of age they stop responding to a pheromone carried in the feces of the lactating female. Because the consumption of such feces promotes the deposition of brain myelin, we suggested that response to the pheromone might continue as long as the amount of myelin per gram brain remained below adult levels. Our data support the suggestion. Pups deficient in myelin responded to the pheromone after 27 days of age.

Animals↗
PubMed1985

At what age do rat young stop responding to the maternal pheromone?

We tested postweanling rat young to see if they would continue to respond to the maternal pheromone when pheromone-containing feces were made available in the home cage. We found that they do, and that the consumption of pheromone-containing feces is important for such sustained responsiveness. Nonetheless, interest in the pheromone does not continue past 50 days of age. The possible adaptive significance of the continuation and cessation of pheromonal responsiveness was discussed.

Adaptation, Biological↗
PubMed1984

Suppression of postpartum fertility in pairs of female rats sharing the same nesting environment.

The probability that a successful pregnancy will follow postpartum estrus in the rat is significantly reduced when the postpartum female is housed with another female that is both pregnant and lactating. We studied 16 pairs of females, each pair maintained in a separate nesting environment containing a sexually active male. In 12 of the pairs, the female that gave birth in the presence of a lactating-pregnant partner either did not mate, mated but failed to implant, resorbed her fetuses or delivered non-viable young. Several mechanisms that might underlie this evident suppression of fertility are discussed.

Animals↗
PubMed1984

The maternal pheromone and brain development in the preweanling rat.

Preweanling rats selectively approach and consume pheromone-containing maternal feces. This selectivity suggests that the consumption of maternal feces might be important for the growing pup. Previous research suggested that such feces might promote brain development. A series of experiments was carried out in which pups were denied access to maternal feces. These pups were clearly inferior to control pups in brain growth and neurobehavioral maturation, as well as in the quantity of brain myelin.

Animal Population Groups↗
PubMed1984

The maternal pheromone and deoxycholic acid in relation to brain myelin in the preweanling rat.

We examined the lipid composition of blood and myelin in preweanling rats denied access to maternal feces. Levels of triglycerides and free fatty acids in the blood were reduced and in the brain the amount of myelin and the phospholipid concentration in myelin were also reduced. The addition of deoxycholic acid to ordinary laboratory chow prevented these deficiencies. We conclude that response to the maternal pheromone and the subsequent ingestion of deoxycholic acid through maternal feces promotes the deposition of normal brain myelin.

Animal Population Groups↗
PubMed1984

The maternal pheromone and deoxycholic acid in the survival of preweanling rats.

Preweanling rats selectively approach and consume pheromone-containing maternal feces. This selectivity suggests that the consumption of maternal feces might be important for the growing pup. We tested the hypothesis that such feces, because of their high deoxycholic acid content, may protect against acute enteritis. A series of experiments was carried out in which pups were denied access to maternal feces. These pups died more often from acute enteritis than control pups. Additional confirmation of the hypothesis was obtained when feces-denied young fed deoxycholic acid showed a significantly lower mortality than feces-denied young fed laboratory chow alone.

Animals↗