Organizational and activational effects of sex steroids on brain and behavior: A reanalysis

The actions of sex steroids on brain and behavior traditionally have been divided into organizational and activational effects. Organizational effects are permanent and occur early in development; activational effects are transient and occur throughout life. Over the past decade, experimental results have accumulated which do not fit such a simple two-process theory. Specifically, the characteristics said to distinguish organizational and activational effects on behavior are sometimes mixed, as when permanent effects occur in adulthood. Attempts to determine whether specific cellular processes are uniquely associated with either organizational or activational effects are unsuccessful. These considerations blur the organizational-activational distinction sufficiently to suggest that a rigid dichotomy is no longer tenable.     

Clinical implications of the organizational and activational effects of hormones

Debate on the relative contributions of nature and nurture to an individual's gender patterns, sexual orientation and gender identity are reviewed as they appeared to this observer starting from the middle of the last century. Particular attention is given to the organization-activation theory in comparison to what might be called a theory of psychosexual neutrality at birth or rearing consistency theory. The organization-activation theory posits that the nervous system of a developing fetus responds to prenatal androgens so that, at a postnatal time, it will determine how sexual behavior is manifest. How organization-activation was or was not considered among different groups and under which circumstances it is considered is basically understood from the research and comments of different investigators and clinicians. The preponderance of evidence seems to indicate that the theory of organization-activation for the development of sexual behavior is certain for non-human mammals and almost certain for humans. This article also follows up on previous clinical critiques and recommendations and makes some new suggestions.     

Parasites and pathogens effects on host hormones and behavior

edited by Nancy E. Beckage, Chapman & Hall, 1997. pound57.00 (338 pages) ISBN 0-412-07401-X.     

Organizational effects of estrogens on brain vasotocin and sexual behavior in quail

Reproductive behavior is sexually differentiated in quail: The male-typical copulatory behavior is never observed in females even after treatment with high doses of testosterone (T). This sex difference in behavioral responsiveness to T is organized during the embryonic period by the exposure of female embryo to estrogens. We showed recently that the sexually dimorphic medial preoptic nucleus (POM), a structure that plays a key role in the activation of male copulatory behavior, is innervated by a dense steroid-sensitive network of vasotocin-immunoreactive (VT-ir) fibers in male quail. This innervation is almost completely absent in the female POM and is not induced by a chronic treatment with T, suggesting that this neurochemical difference could be organizational in nature. This idea was tested by injecting fertilized quail eggs of both sexes on day 9 of incubation with either estradiol benzoate (EB) (25 μg, a treatment that suppresses the capacity to show copulatory behavior in adulthood) or the aromatase inhibitor R76713 (10 μg, a treatment that makes adult females behaviorally responsive to T), or with the solvents as a control (C). At 3 weeks posthatch, all subjects were gonadectomized and later implanted with Silastic capsules filled with T. Two weeks later, all birds were perfused and brain sections were processed for VT immunocytochemistry. Despite the similarity of the adult endocrine conditions of the subjects (all were gonadectomized and treated with T Silastic implants providing the same plasma level of steroid to all subjects), major qualitative differences were observed in the density of VT-ir structures in the POM of the different groups. Dense immunoreactive structures (fibers and a few cells) were observed in the POM of C males but not females; EB males had completely lost this immunoreactivity (and lost the capacity to display copulatory behavior); and, conversely, R76713 females displayed a male-typical VT-ir system in the nucleus (and also high levels of copulatory behavior). Similar changes in immunoreactivity were seen in the nucleus of the stria terminalis and in the lateral septum (VT-ir fibers only in this case) but not in the magnocellular vasotocinergic system. These neurochemical changes closely parallel the effects of the embryonic treatments on male copulatory behavior. The vasotocinergic system of the POM can therefore be considered an accurate marker of the sexual differentiation of brain circuits mediating this behavior. © 1998 John Wiley & Sons, Inc. J Neurobiol 37: 684–699, 1998     

植物挥发性物质对昆虫作用的研究进展

不同植物的挥发性物质对昆虫行为有着不同的调节作用,部分对害虫表现为引诱作用,部分对害虫表现为驱避和致死作用,有的则表现为寄主植物与天敌昆虫之间的互惠引诱定位作用。本文综述了近年国内外有关植物挥发性物质的研究概况及其对昆虫的不同作用,展望了其在未来害虫综合治理中的应用。     

Organizational effects of maternal testosterone on reproductive behavior of adult house sparrows

Despite the well-known, long-term, organizational actions of sex steroids on phenotypic differences between the sexes, studies of maternal steroids in the vertebrate egg have mainly focused on effects seen in early life. Long-term organizational effects of yolk hormones on adult behavior and the underlying mechanisms that generate them have been largely ignored. Using an experiment in which hand-reared house sparrows (Passer domesticus) from testosterone- or control-treated eggs were kept under identical conditions, we show that testosterone treatment in the egg increased the frequency of aggressive, dominance, and sexual behavior of 1-year-old, reproductively competent house sparrows. We also show that circulating plasma levels of progesterone, testosterone, 5alpha-dihydrotestosterone, and 17beta-estradiol did not differ between treatment groups. Thus, a simple change in adult gonadal hormone secretion is not the primary physiological cause of long-term effects of maternal steroids on adult behavior. Rather, differences in adult behavior caused by exposure to yolk testosterone during embryonic development are likely generated by organizational modifications of brain function. Furthermore, our data provide evidence that hormone-mediated maternal effects are an epigenetic mechanism causing intra-sexual variation in adult behavioral phenotype.     

Gonadal hormones and sex differences in nonreproductive behaviors in rodents: organizational and activational influences

Sex differences in many nonreproductive behaviors have been described in rodents. Among the behaviors that are sexually dimorphic in the rat are activity, aggression, pain, and taste sensitivity, food intake and body weight regulation, the learning and retention of certain kinds of mazes, avoidance responses, taste aversion, and performance on certain schedules of reinforcement. Gonadal hormones seem to be responsible, in part, for sex differences in these behaviors, but their contribution varies greatly with the behavior in question. Frequently, these sexually dimorphic behaviors are influenced both by organizational and activational actions of sex hormones. In other instances (e.g., maze learning and the acquisition of shuttle-box avoidance responses) organizational influences predominate. And while there is no sexually dimorphic behavior surveyed that can be shown to be influenced only by activational effects, wheel-running activity is clearly more strongly subject to activational than to organizational effects of the gonadal hormones. In general, only rudimentary information exists regarding the temporal limits of the period in development when organizational influences on nonsexual behaviors occur. The suggestion can be made that organizational influences often occur outside of the critical period for differentiation of the neuroendocrine system regulating cyclic release of gonadotrophins. Even for behaviors where organizational effects usually occur during a roughly delimited period of development, data for other behavioral systems suggest that the time limits during which organizational effects can occur are not rigidly fixed. Very little information exists regarding biochemical or neural mechanisms by which organizational or activational effects on sexually dimorphic nonreproductive behaviors are expressed. It is important to recognize for many of the sexually dimorphic behaviors in the rat that differences between the sexes are neither large nor absolute. This is especially true of several kinds of learning situations where groups of males and females typically differ in average levels of performance. Ostensibly minor variations in test procedure can abolish or accentuate the average difference in performance between the sexes. We are a long way from an adequate understanding of what factors are important, but such information could be quite helpful in estimating whether sex differences in certain laboratory learning tasks have any adaptive significance.Sex differences in nonreproductive behaviors may be influenced by many factors other than hormonal status. This greatly complicates a comparative analysis, but such an analysis will ultimately be necessary. What limited data exist on rodents suggest that: (1) Sexually dimorphic responses in the rat are often not similarly differentiated in the hamster, the gerbil, or the mouse; and (2) major differences exist among rodent species in hormonal effects on such responses.Over the last decade it has become clear that the behavioral effects of deliberate neurological insult are not necessarily the same in male and female rats (or in one case, in rhesus monkeys). Sex differences in the behavioral effects of ventromedial hypothalamic, lateral hypothalamic, septal, and striatal lesions in the rat and of orbital prefrontal cortex lesions in the monkey have been described. While information regarding hormonal modulation of these differences in response to brain damage is very limited, available data suggest both organizational and activational effects of sex hormones may be involved. It is too early to tell where this line of research may ultimately lead, but rather striking sex differences in the incidence of certain neurological disorders in humans suggest that further research may have both practical and theoretical significance.     

Social factors modulate the effects of hormones on the sexual and aggressive behavior of macaques

We previously reviewed the effects of gonadal hormones on the sexual and aggressive behavior of macaques as observed in field, outdoor colony, and laboratory studies. There were consistent similarities between findings from different observational settings, but there were also noteworthy differences which suggested the importance of social and environmental factors in modulating the effects of hormones. We now examine the role of these factors further and consider the extent to which partner preferences, familiarity between individuals, and also dominance rank can affect the behavior of male-female pairs and thereby modify the influences of hormones. The evidence suggests that all these factors are important. Hormone-dependent short-term partner preferences appear to be critical for the formation of consort bonds and to facilitate mating between unfamiliar partners. Socially based partner preferences tend to dampen hormonal influences and may lead to long-term familiarity. Long-term familiarity decreases sexual interactions and may be a proximate mechanism underlying incest avoidance and periodic male troop transfers. Both males and females exhibit mate competition under certain conditions, and their dominance rank can modify sexual and aggressive behavior by either optimizing or reducing hormone-dependent changes. These interaction effects between social and hormonal variables also have relevance for the design and interpretation of laboratory experiments. © 1996 Wiley-Liss, Inc.     

Preventing insect diapause with hormones and cholera toxin

The decision to enter pupal diapause can be reversed in the flesh fly $\text{Sarcophaga crassipalpis}$ by treatment with a juvenile hormone analogue, ecdysterone, or cholera toxin. A topical application of juvenile hormone analogue (10μg) is effective in preventing diapause if applied to newly ecdysed 3rd instar larvae. An ecdysterone injection (1μg) into post-fed 3rd instar larvae can avert diapause, and even lower dosages (0.01μg) are effective if injected into young pupae immediately before the onset of diapause. Cholera toxin, a stimulant of adenylate cyclase, can prevent diapause if 1μg is injected into larvae 24 hrs. prior to pupariation. This is the first report of an effect of cholera toxin on insects. A 2-day exposure to 33°C was the only physical manipulation shown to be capable of reversing the previous commitment to enter pupal diapause.     

Coherence between biosynthesis and secretion of insect adipokinetic hormones

The importance of the process of continuous biosynthesis of locust adipokinetic hormones (AKHs) for the availability of these peptide hormones for release was assessed in vitro by inhibiting this biosynthesis followed by secretory stimulation. Inhibition of the biosynthetic activity for AKHs by brefeldin A caused a considerable inhibition of the AKH release induced by the endogenous crustacean cardioactive peptide (CCAP). After brefeldin A treatment followed by potassium depolarization, CCAP-induced AKH release was completely abolished. In vitro pulse-chase labeling experiments indicated that constitutive secretion from the AKH-producing cells does not occur. It is concluded that AKH secretion involves a regulated release from a relatively small pool of newly formed secretory granules, while older AKH-containing granules appear to be unavailable for release.     

信息化合物对昆虫行为的影响

本文综述了来自寄主植物的挥发性物质和同种昆虫或异种昆虫释放的各种信息素及两者的协同作用的信息化合物对昆虫行为的影响。特别强调了寄主植物的气味物质和昆虫信息素协同作用在昆虫寻找寄主、求偶、交配及天敌在寄主识别过程中的重要地位。昆虫对寄主植物的识别是由于识别了植物气味的由一定组分、按照严格比例组成的化学指纹图。昆虫信息素与植物挥发性物质相结合为昆虫寻找求偶、交配场所提供更复杂或更全面的信息。许多昆虫只有在寄主植物或寄主植物气味存在时 ,才能释放性或聚集信息素。天敌在寄主识别、搜索及定位等一系列过程中 ,来自寄主的食料、寄主本身及两者的互作的信息化合物起重要的作用。研究信息化合物对昆虫行为的影响可以探索昆虫各种行为的内在机理 ,更好的了解寄主—昆虫—天敌三层营养关系的相互作用 ,对利用天然活性化合物防治害虫及生物防治提供理论依据     

Combined organizational and activational effects of short and long photoperiods on spatial and temporal memory in rats

The present study examined the effects of photoperiod on spatial and temporal memory in adult Sprague-Dawley rats that were conceived and reared in different day lengths, i.e., short day (SD-8:16 light/dark) and long day (LD-16:8 light/dark). Both male and female LD rats demonstrated increased spatial memory capacity as evidenced by a lower number of choices to criterion in a 12-arm radial maze task relative to the performance of SD rats. SD rats also demonstrated a distortion in the content of temporal memory as evidenced by a proportional rightward shift in the 20 and 60 s temporal criteria trained using the peak-interval procedure that is consistent with reduced cholinergic function. The conclusion is that both spatial and temporal memory are sensitive to photoperiod variation in laboratory rats in a manner similar to that previously observed for reproductive behaviour.     

Glucagon-like and insulin-like hormones of the insect neurosecretory system.

Aqueous extracts of corpus cardiacum-corpus allatum complexes of the adult tobacco hornworm Manduca sexta produced both glycogenolysis and hypoglycaemia when injected into the larval form of the same species. Application of specific radioimmuno assays to similar extracts showed also that these gland complexes contain both glucagon-like and insulin-like peptides. Further, the partially purified immunoreactive peptides had the expected biological activities. The former decreased the glycogen content of the fatbody and the latter the circulating trehalose levels in recipient animals. These results suggest the existence of hormones in these invertebrates having both biological and structural similarities to vertebrate insulin and glucagon.     

Neurohypophyseal hormones and behavior: effects of intracerebroventricularly injected hormone analogs in mice.

Neurohypophyseal hormones evoke spontaneous behavioral changes in mice. This study compares the potency of four naturally occuring neurohypophyseal hormones and of ten analogs with amino acid residue replacements selected in such a manner as to cover each residue position of the hormones with the exception of the cystine residue. Peptides were administered intraventricularly and the sum of foraging, scratching and squeaking, recorded at 30 second intervals during a 30 min session, was measured as a function of peptide dose. The most potent group of peptides is represented by the neurohypophyseal hormones as well as the five analogs [Hly⁸] vasopressin, [Δ³-Pro⁷]AVP, [Thi³]LVP, [Abu⁴]AVP and [Abu⁴]LVP. [Leu⁴]LVP showed significant activity but was far less potent than the natural hormones. None of the remaining analogs enhanced activity with an increase in peptide dose. This group included both peptides with C-terminal modifications and those in which the tyrosine (position 2) or the asparagine residue (position 5) of the hormones were substituted by alanine. The neurohypophyseal hormone-induced behavioral results of this study reveal a structure-function relationship, which is in its most important conclusions, identical to the conformation-activity model proposed for endocrine activities of neurohypophyseal peptides.