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Pituitary Hormones in Sexual Behavior
Because of the effects which secretions from the anterior lobe of the pituitary gland may have on all of the other endocrine organs, and particularly on the gonads and adrenal glands, the pituitary has often been described as a master gland dominating all of the other endocrine organs in the body. It seems, however, more correct to think of the gonads and the pituitary and adrenal glands as a chain of organs whose secretions have interlocking effects. The effect of the pituitary on the gonads, for instance, seems hardly more significant than the effect of the gonads on the pituitary.

Relation of Pituitary to Physical Characters
Damage to the anterior lobe of the pituitary in a young animal, or in the human female or male before the onset of adolescence, may affect physical development more seriously than a gonadal castration. In the case of the human female or male, the individual remains immature or develops slowly and at a late age, and is abnormal in his or her physical proportions and functions. However, the effects of a pituitary insufficiency in a young animal may be relieved by the administration of pituitary hormones. Because of the general, regulatory function of the pituitary gland, some laboratory students and some clinicians are inclined to depend upon pituitary hormones to correct a gonadal insufficiency.
The physical effect of pituitary damage in young animals and human subjects, and subsequent hormonal therapy are discussed in: Pratt in Allen et al. 1939: 1294. Corner 1942:141 (females), 222 (males). Greenblatt 1947:183. Beach 1948:12-17, 22, 208. Selye 1949:262-317. Williams 1950:ch.2. Howard and Scott in Williams 1950:318-319. Ford and Beach 1951:167-169. Dempsey in Stevens 1951:221.

It is reported that the administration of pituitary hormones to a normal pre-adolescent in whom there is neither a pituitary nor a gonadal insufficiency, may induce a precocious adolescent development.
Precocious adolescent development resulting from the pituitary treatment of young animals is described in: Smith and Engle 1927 (ablation of thyroid made no difference, showing it was not involved; mice, rats, cats, rabbits, guinea pigs). Young 1941:322. Beach 1948:12-16. Burrows 1949:22-23, 39. Ford and Beach 1951:168-170.

Relation of Pituitary to Sexual Behavior
A pre-adolescent pituitary deficiency affects the sexual behavior of an animal in much the same way that an early castration affects its sexual behavior. Responsiveness develops slowly if at all, and it is probable that the levels of response which are ultimately reached by such an individual are below those which are normal.
That a lack of pituitary hormone depresses sex drive, is reported by: Burrows 1949:169. Selye 1949:271-282. Williams 1950:43, 46.

Since the gonads are among the structures which do not develop normally when there is an early pituitary insufficiency, the effects of the pituitary hormones on sexual behavior may depend upon their regulation of the supply of gonadal hormones, and this interpretation is favored by the fact that the administration of androgens to an animal which has a pituitary deficiency may induce normal sexual behavior. On the other hand, it is also possible that the pituitary hormones directly affect the development and the physiologic function of the nervous system on which sexual behavior depends.
Conversely, the effect of the nervous system on the secretory capacity of the pituitary is well-known. Examples of such neural control are in: Hoffman 1944:309-310 (suppression of menses). Hartman 1945:27 (rabbit ovulation). C. D. Turner 1948:364-365 (pseudopregnancy). Durand-Wever 1952:209-211 (gonads deteriorate as a result of fear). Talbot et al. 1952:302-303 (puberty depends on neural mechanisms operating via pituitary).

Because the pituitary glands are not located near the organs of reproduction, there are only scattered references to the effects of pituitary deficiencies on sexual behavior. The opinion is generally held that such deficiencies in adults, or the administration of pituitary hormones in cases of deficiencies, or the administration of pituitary hormones to normal adults, does not have as pronounced an effect on sexual behavior as the administration of gonadal hormones.

Pituitary Secretions and Levels of Sexual Response
There are indications that the levels of pituitary secretion may correlate with the fundamental patterns of sexual behavior which we have found in the human female and male. Recently published studies on fowl show that the cells of the anterior lobe of the pituitary in a very young male contain a quite clear cytoplasm, which, however, begins to accumulate granular materials, the so-called mitochondria, soon after the animal begins to grow. These mitochondria are associated with the normal physiologic processes that go on in these cells, but as the male animal ages, the mitochondria steadily increase in quantity until the cells of the glands of the older male become more or less filled with the granular inclusions.
For the relation of age to the mitochondria in the cells of the anterior lobe of the pituitary, see: Payne 1949:197-198. Payne in Cowdry 1952:385.

The secretory capacity of the cell is inversely proportional to the volume of the granular inclusions in the cell and therefore to the age of the animal, and in the older male bird the cells may, in consequence, lose most of their secretory capacity. The functional significance of the pituitary is therefore steadily lowered as the male becomes more advanced in age.

On the other hand, the cells of the anterior lobe of the pituitary of the female do not accumulate such a quantity of granular material, and cases are reported of ten- and twelve-year-old female birds in which the cells of the anterior lobe of the pituitary are practically as clear of mitochondria as they are in very young females. This means that the secretory capacities of the pituitaries of these females are maintained at a more or less constant level throughout the life of the bird.

This gradual loss of function in the cells of the pituitary of the males, among fowls, parallels the steady decline which we have found in the sexual activities of the human male. The maintenance of pituitary function on a more or less constant level in the females, among fowls, parallels the maintenance of sexual capacity which we have found in the human female. Among all of the biologic phenomena which we are aware of, these differences between female and male pituitary secretion, and the differences which we shall note below in the levels of the 17-ketosteroids among females and males, are the only phenomena that seem to parallel the differences which we find between the sexual activities of the human female and male.

Since cytologic and experimental studies of these differences in female and male pituitary functions are of very recent date, we have no idea whether such a differentiation applies to the human or to any other species of mammal. If the differentiation does hold in the human species, it does not necessarily imply that there is any simple, causal relationship between pituitary secretions and sexual behavior. The relationship may depend upon a whole chain of physiologic phenomena which are initiated by the pituitary hormones; or the pituitary picture may reflect some other physiologic condition of the female on which both pituitary and sexual function depend. In any event there is a parallel between these reported pituitary functions in the bird, and the data which we have on the sexual behavior of the human female and male. We did not find such a correlation between the levels of gonadal hormones and the patterns of human sexual behavior.

Thyroid Hormones
Thyroid secretions have well known effects upon the general physiologic level of an animal’s activities, including its nervous responses. Low levels of thyroid secretion lower the rates of most activities, and high levels raise the rates of activity; but there is no invariable relationship for, once again, the effects depend upon the concomitance of various other factors which may also influence metabolic activities. It is reported that male hormones tend to stimulate thyroid function, but female hormones are said to inhibit their function, thereby reducing metabolic levels.
Effects of male and female hormones on thyroid function are noted in: Hoffman 1944:240-241 (reciprocal relationship). Williams 1950:115 (estrogen antagonizes thyroid function; testosterone stimulates thyroid and increases metabolic rate).

It is well known that early insufficiencies of thyroid secretions may delay or modify adolescent physical developments and lead to an infantilism of genital structures in both females and males. Cases of such adolescent deficiencies which we have in our histories, show delayed or low levels of sexual response and activity.
Delayed adolescence resulting from lack of thyroid is described in: Lisser 1942. Hoffman 1944:239. Williams 1950:173-175. Talbot et al 1952:21. 31.

There are few published data, but there is a rather widespread clinical understanding that thyroid deficiencies in an older individual may be associated with some lack of responsiveness, and an excess may be associated with rates of sexual activity which are above the average. Not a few physicians administer preparations of thyroid in order to increase the responsiveness of some of their patients. We have some histories of females and a fair number of histories of males to whom thyroid extracts were administered with that express purpose. In some cases, increased frequencies of coitus seem to have been the direct consequence of this therapy, in other cases the record did not seem to indicate that there was any modification of sexual activity, and in some cases a decrease in sexual activity was reported after the thyroid administration. It is, of course, difficult to know how much of the reported change in any particular case was the direct result of the administration of the hormone, how much was the consequence of a change in other physiologic functions, and how much depended on social situations.

Just as some physicians have used testosterone to increase the frequencies of coitus in cases of sterility in which the sterility appeared to be a consequence of low rates of coitus, so there are some who use thyroid to accomplish the same end. Just as with the administration of gonadal hormones, there are reports that such thyroid therapy increases the sperm count and the motility and viability of the sperm, thereby increasing the chances for conception to occur. There is, however, a considerable need for the accumulation of more specific data on these matters, and more carefully controlled experimentation. Since the administration of thyroid extracts may affect a number of other body functions, there is need for caution in the use of these hormones in any attempt to control sexual responses.
The administration of thyroid in sterility cases is noted in: Siegler 1944:311-313. Smith in Williams 1950:430. Mazer and Israel 1951:461, 488 (to increase sperm count).

Adrenal Hormones
The adrenal glands are paired organs lying above the kidneys, which places them in the small of the back of the human animal. They are known to produce a considerable number—perhaps twenty or thirty or more—chemical compounds (steroids) which function as hormones. The possibility that some of these are related to sexual behavior has been considered for some time, but there are still few specific data to establish such a relationship.

Adrenaline
The best known of the secretions of the adrenal glands is adrenaline. This is a product of the central core, the medulla, of the adrenal organ. The role of adrenaline in various types of emotional response, and particularly in the case of fear and fright, was one of the first things known about the glands of internal secretion.

Because many of the gross physiologic changes which occur during sexual response are similar to those which may be induced in an animal by injecting it with adrenaline, or by stimulating it so its adrenal glands secrete an extra supply of adrenaline, it has frequently been suggested that adrenaline is responsible for the initiation of sexual response or for some portion of it.

On the other hand, there is a longstanding theory that adrenaline interferes with sexual responses. The theory may have originated in the observation that persons who are frightened during sexual activity may have their activity interrupted. There are, however, no experimental data to establish this inhibitory effect of adrenaline on sexual response.
The opinion that adrenaline interferes with sexual response, or inhibits erection, is implied or specifically stated in: Cannon 1920:270-271. Kuntz 1945:311.

Sexual reactions may so quickly involve the whole animal body that it is difficult to believe that a blood-circulated agent such as adrenaline could be responsible for the major body of physiologic changes which constitute sexual response. Nevertheless, many of the physiologic phenomena involved in sexual response, and particularly the activity of the autonomic nervous system during sexual response, may lead to the secretion of adrenaline, and it is quite possible that some of the phenomena seen in the later stages of sexual response may be products of adrenaline secretion.

Cortical Hormones
The outer portion of the adrenal organ, its cortex, is the source of a variety of hormones, including androgens, estrogens, and the various compounds known as the 17-ketosteroids. It is understandable that the adrenal cortex should have some of the same functions as the gonads, for the testes, the ovaries, and the cortex of the adrenals originate from a common embryonic cell mass, even though the organs into which they develop may move apart in the adult anatomy. It has generally been considered that the effects of a gonadal castration are not more severe than they are because the adrenal cortex shares some of the responsibility for the production of the same hormones. The importance of the adrenals in this regard, however, may have been overemphasized in the earlier literature.
The compensatory function of the adrenal cortex in castrates is described in: Burrows 1949:189. Dempsey in Stevens 1951:216 (potency of male depressed more severely by destroying adrenals than by castration).

The 17-ketosteroids are so called because they have a ketone group at the 17 position on the molecule. Some, but not all, of the 17-ketosteroids are androgens. The 17-ketosteroids are supposed to originate in various organs, including the gonads and the adrenal cortex. It has been estimated that the adrenal cortex may produce as much as 60 or 70 per cent of the 17-ketosteroids found in the mammalian body; but the removal of both the testes and the adrenal cortex in a laboratory animal does not wholly deprive it of its 17-ketosteroids, and this indicates that other organs also produce these compounds.
For the relative importance of the cortex in supplying 17-ketosteroids in the body see: Fraser et al. 1941:255 (two-thirds adrenal in male, all from adrenal in female). Dorfman et al. 1947:487 (17-ketosteroids still significant in male and female monkeys 40 days after removal of both gonads and adrenals). Hamburger 1948:31-32. Dempsey in Stevens 1951:215 (one-third gonadal, remainder from adrenal cortex). Engle in Cowdry 1952:712 (two-thirds from adrenal). Maddock et al. 1952:668 (both testes and cortex are important).

Figure 155f. Levels of 17-Ketosteroids in Human Female and Male

Showing aging effect in male, and a prolonged plateau in the female,
somewhat similar to average median frequencies of total outlet
among females and males shown in Figure 143f.
Data from Hamburger 1948.


There are suggestions in the literature that the 17-ketosteroids are in some fashion related to levels of sexual responsiveness, and to frequencies of overt sexual activity in a mammal. The suggestions, however, have been theoretic, and there seems to have been no demonstration of such a relationship in either experimental or clinical data. We do find, however, that die reported levels of the 17-ketosteroids in the human male differ from the reported levels of the 17-ketosteroids in the human female in a manner which more or less parallels the differences which we have found between the median frequencies of orgasm at various ages in the two sexes (compare Figures 143f and 155).
Data on levels of 17-ketosteroids are found in the following sources; Fraser et al. 1941:237-255 (shows decrease in older ages, both male and female). Talbot et al. 1943:364. Hamburger 1948:34. Hamilton and Hamilton 1948: 438. Howard et al. 1950:127 if. Salter, Humm, and Oesterling 1948:302-303, fig. 3 (decrease with age in male after twenties). Kenigsberg, Pearson, and McGavack 1949:426-427 (in males increase up to thirties, decrease thereafter. In contrast to other studies, notes no changes in twenty females aged 17 to 64).

It is reported that the 17-ketosteroids increase sharply in the urine of the developing human male at the approach of adolescence and during early adolescence (Figure 155). They reach a peak in the late teens or early twenties in the male, but from that point they drop steadily into old age. Consequently, the levels of sexual activity in the human male more closely match the levels of the 17-ketosteroids than the levels of gonadal hormones. We have already noted that there is also a parallel to the human male behavior curves, in the secretory capacity of the anterior lobe of the pituitary in one species of laboratory animal.

The levels of the 17-ketosteroids which are reported for the human female are quite different from those reported for the male (Figure 155). During adolescence and the later teens, there is a sharp rise in the ketosteroid levels of the female. The curve reaches its peak somewhere in the middle twenties, shows a rather sharp drop in the next ten years, and then lies on a plateau for some years. It continues on this level through menopause and into the middle fifties, and does not show a further drop until the late fifties or sixties. Another study shows a more or less continuous plateau from ages seventeen to sixty-four, without the teen-age rise which the first-mentioned study showed. This plateau parallels the plateau which we have found in the sexual activities of the female (Figure 143f). The chief difference lies in the rise in the 17-ketosteroids reported in one study during the late teens and early twenties, and this rise is not found in the female’s sexual performance. This may raise a question as to the significance of the correlation; but it is also clear that a part of the lack of sexual response in the younger American female is a product of cultural restraints on her sexual performance. We have presented evidence for this throughout the present volume, particularly in connection with the data showing the effect of the religious tradition on her behavior.

These correlations between ketosteroid levels and the sexual activities of the human female and male may represent a simple causal relationship, or each of these phenomena may be a product of some other basic physiologic phenomenon, or of a whole complex of physiologic phenomena which are responsible for adrenal function, for pituitary function, and for the capacities of the nervous system to be affected by what we call sexual stimuli.

Hormones and Patterns of Sexual Behavior

While the data which we have presented show that hormones may affect the capacity of the central nervous system to be stimulated sexually, and therefore may affect the levels of sexual response, there are no data which warrant the conclusion that an individual’s choice of a sexual partner or of a particular type of sexual activity may be directly influenced by any of the hormones. As far as sexual performance is concerned, it is incorrect to think of endocrine organs as the glands of personality.

We have already pointed out that the sexual capacity of an animal depends upon its inherited anatomy and particularly upon its nervous structures and the physiologic capacities of those structures. The capacity of an animal to be aroused by tactile stimuli or psychologic stimuli, and to respond with a development of neuromuscular tensions which produce, among other things, the rhythmic pelvic thrusts which are typical of mammalian coitus, is a capacity which is inherent at birth.

We have also emphasized that all organisms, and particularly such highly evolved organisms as the human animal, are conditioned by their experience, and consequently in the course of time come to respond more readily to particular types of stimuli. Thus, they develop preferences for the repetition of those types of sexual experience which have been most satisfactory, and become conditioned against the repetition of those types of sexual activity which have been unsatisfactory. In addition to being affected by firsthand experience, the individual may be conditioned by the reported experience of his or her friends, and by the social tradition. Such conditioning seems a sufficient explanation of a preference for a sexual partner who is a blonde or a brunette, or a preference for a sexual partner of the same or of the opposite sex, or for the utilization of one type of technique rather than another in the course of a sexual relationship. It is curious that psychologists and psychiatrists, who are the ones who most often emphasize the importance of psychologic conditioning, so often look for hormonal explanations of any type of sexual behavior which departs from the Hittite and Talmudic codes.

On the unwarranted assumption that homosexuality represents some sort of femininity in an anatomic male, and masculinity in an anatomic female, there have been clinical attempts to redirect the sexual behavior of homosexual males, and occasionally of homosexual females, by giving them gonadal hormones. Recent suggestions concerning the importance of the 17-ketosteroids have led to investigations of the possibilities of using those substances to control behavior. Certain clinicians have developed a lucrative business supplying hormones to patients with homosexual histories, and androgens have been given males who have been discovered in homosexual activity in penal institutions, in the Armed Forces, and elsewhere. Certain of the drug companies have encouraged the use of male hormones for this purpose.

The possibility that hormones might modify homosexual patterns of behavior found some encouragement in early reports on the hormonal injections of laboratory animals. These reports, unfortunately, involved an erroneous use of the term homosexual. Among most of the mammals a female in heterosexual coitus typically assumes a crouched position, often with her head drawn down and her haunches raised in a manner which allows the male to mount in coitus. The female rat arches her back convexly (in a lordosis) and her ears go into a tremor. The male, on the other hand, typically sits or rises on his hind legs while he effects coitus. The assumption of the crouched position by a male during a sexual relationship, or the assumption of an upright position by a female, was recorded in the earlier literature on animal behavior as a sex reversal or homosexual activity. But this use of the term had no relation to its use in human psychology, where homosexual refers to the choice of a partner of the same sex.
The concept of a “reversal” of “masculinity” or “femininity” in sexual behavior among lower mammals is found, for instance, in: Ball 1937, 1939, 1940. Beach 1938, 1941, 1942b, 1945, 1947b. Young and Rundlett 1939:449 (labelling such a reversal homosexual). Beach corrects this interpretation in: Beach 1948:68. Ford and Beach 1951:41-42.

We have already noted that rats which are injected with testosterone become more aggressive in all of their behavior, including their sexual behavior, and that females who are given testosterone mount other females and males more frequently than they did before they were given the hormones. But they do this because their aggressiveness has been increased; and when they mount males their behavior is still heterosexual and not homosexual, even though the positions assumed in the coitus have been reversed.

In connection with the clinical treatment of homosexuality there are, of course, reports of “good results,” but no adequate data to show that the behavioral patterns of such subjects have ever been modified by hormonal treatments. We have the histories of an appreciable number of males who had received hormonal treatments, but we have never seen an instance in which a homosexual pattern had been eliminated by such therapy. Not infrequently, however, the levels of sexual responsiveness had been raised by the treatment with male hormones, and this, in many instances, had complicated the situation by increasing the capacity of the homosexual individual to be aroused by homosexual stimuli. Such failures to attain the desired results in therapy had led to social tragedies in a number of the cases.
For the hormonal treatment of homosexual cases, see: Barahal 1940:329 (7 cases, increased the sex drive of homosexuals, failed to change its direction). Glass, Deuel and Wright 1940. Kinsey 1941 (a critical appraisal of earlier data). Glass and Johnson 1944 (some benefit in 3 cases; no benefit in 8). T. V. Moore 1945:80. Heller and Maddock 1947:419-422 (a well balanced discussion). Perloff 1949:136-139. Howard and Scott in Williams 1950:333. Brown 1950: 52-53 (300 male homosexuals, unsuccessful treatment with androgens).

Summary and Conclusions

Our present understanding of the relations between hormones and the sexual behavior of the human female and male may, then, be summarized as follows:

1.      The early development of sexual responsiveness in the human male and its later development in the female, the location of the period of maximum responsiveness for the male in the late teens and early twenties and for the female in the late twenties, the subsequent decline of the male’s sexual capacities from that peak into old age, and the maintenance of female responsiveness on something of a level throughout most of her life, are patterns which are not explained by the known anatomy or physiology of sexual response. Neither are they explained by the known differences in the capacities of females and males to be aroused by psychosexual stimuli.

2.    Various hormones may affect the levels of sexual responsiveness in the human female and male because of their effects on the levels of all physiologic activities, including those capacities of the nervous system on which sexual behavior depends.

3.    Estrogens, the so-called female hormones, originate primarily in the ovaries and the adrenal cortex. Androgens, the so-called male hormones, originate in the testes, the adrenal cortex, and still other organs. Both estrogens and androgens are present in both females and males. They occur in about equal abundance in human females and males in the pre-adolescent years, but during adolescence the androgens rise to a somewhat higher level in the male, and the estrogens rise to a much higher level in the female. In neither sex, however, does this rise correlate with the levels of sexual responsiveness in the adolescent or older female or male.

4.    Gonadal hormones are among the elements necessary for normal physical development in young animals, both female and male. Consequently they are necessary for the development of the capacities of the nervous system and therefore may, indirectly, affect the development of sexual responsiveness in the female and male.

5.    In human adults, gonadal hormones may be withdrawn (as in a castration) with minimum effects on physical characters, with a minimum or no effect on the sexual responsiveness of the female, and with little or no effect on the sexual responsiveness of half or more of the males. In a smaller number of cases there may be a slow physical degeneration in the male which may be accompanied by a reduction in his sexual responsiveness.

6.    Estrogen and androgen levels, as far as they are known in the normal human female and male, do not correlate with the frequencies of sexual activity in the two sexes. There seem to be no correlations with the aging patterns of the male in his sexual performance, and with the female’s maintenance of a level of response throughout most of her life.

7.    Increased supplies of androgens given to adult human females or males do raise their levels of sexual response. There is serious danger, however, in the administration of such hormones except under the direction of an experienced clinician.

8.    Pituitary hormones are also among the elements necessary for the normal physical development of the female and male, and for the development of many physiologic capacities, including those capacities of the nervous system upon which sexual behavior depends.

9.      The levels of pituitary secretion are known to drop steadily among the males of one species of laboratory animal, while the levels of pituitary secretion in the female of the same species may remain constant for some years. If this is also true of the human species, this would parallel the differences which we find in levels of sexual responsiveness among human females and males. The correlations might represent a causal relationship, or both phenomena might be independent products of more basic physiologic factors.

10.    The levels of thyroid secretion sometimes show a direct correlation with the levels of sexual responsiveness. Higher thyroid levels sometimes correlate with higher levels of response, and lower thyroid levels sometimes correlate with lower levels of response; but the correlations are not invariable, for there appear to be other factors which determine the effectiveness of the hormone from the thyroid.

11.    Adrenaline, from the medulla of the adrenal glands, does not seem to be involved in the initiation of sexual response. However, as sexual activities progress, the adrenal glands may be stimulated into secretion, and this secretion may be responsible for certain of the phenomena which appear in the later stages of sexual activity. There is no evidence that adrenaline actually inhibits sexual response.

12.    The levels of the 17-ketosteroids, which originate largely in the adrenal cortex but also develop in the testes and ovaries and apparently in other organs of the body, show rather striking correlations with the levels of sexual response in the human female and male. In the human male, the 17-ketosteroids drop steadily from a peak in the late teens or twenties into old age, while they remain on a plateau for some period of years in the female. Again, this may represent a direct causal relationship, or (what is more likely) both the 17-ketosteroids and the levels of sexual responsiveness may reflect a more basic and probably more complex physiologic situation.

13.    While hormonal levels may affect the levels of sexual response— the intensity of response, the frequency of response, the frequency of overt sexual activity—there is no demonstrated relationship between any of the hormones and an individual’s response to particular sorts of psychologic stimuli, an individual’s interest in partners of a particular sex, or an individual’s utilization of particular techniques in his or her sexual activity. Within limits, the levels of sexual response may be modified by reducing or increasing the amount of available hormone, but there seems to be no reason for believing that the patterns of sexual behavior may be modified by hormonal therapy.

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