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PubMed2005

Seasonal variations in mood and behaviour associated with gender, annual income and education: the Hordaland Health Study.

OBJECTIVE: To explore the relationship between demographic factors and seasonal changes in mood and behaviour. METHOD: A health survey was conducted among 40-45 year old inhabitants in Hordaland County, Norway. The Global Seasonality Score, investigating seasonal symptoms, was given to 4299 men and 9983 women. Response rates among those receiving the questionnaire were 79.8% for men (n = 3432) and 81.2% for women (n = 8223). RESULTS: High seasonality was reported by 18.4% of men and 22.2% of women. Female gender, low educational level, high level of affective symptomatology and low household income correlated with high seasonality. Among men, being single was also a determinant factor for high seasonality. Reported seasonality also depended on which month the questionnaire was filled in. CONCLUSIONS: In this study, high seasonality was most prevalent among females, being single, having a low annual income and a low education level. The latter two findings are different from expectations which could be drawn from previous studies suggesting an opposite association.

Adult↗
PubMed1998

Chronic fatigue syndrome and seasonal affective disorder: comorbidity, diagnostic overlap, and implications for treatment.

This study aimed to determine symptom patterns in patients with chronic fatigue syndrome (CFS), in summer and winter. Comparison data for patients with seasonal affective disorder (SAD) were used to evaluate seasonal variation in mood and behavior, atypical neurovegetative symptoms characteristic of SAD, and somatic symptoms characteristic of CFS. Rating scale questionnaires were mailed to patients previously diagnosed with CFS. Instruments included the Personal Inventory for Depression and SAD (PIDS) and the Systematic Assessment for Treatment Emergent Effects (SAFTEE), which catalogs the current severity of a wide range of somatic, behavioral, and affective symptoms. Data sets from 110 CFS patients matched across seasons were entered into the analysis. Symptoms that conform with the Centers for Disease Control and Prevention (CDC) case definition of CFS were rated as moderate to very severe during the winter months by varying proportions of patients (from 43% for lymph node pain or enlargement, to 79% for muscle, joint, or bone pain). Fatigue was reported by 92%. Prominent affective symptoms included irritability (55%), depressed mood (52%), and anxiety (51%). Retrospective monthly ratings of mood, social activity, energy, sleep duration, amount eaten, and weight change showed a coherent pattern of winter worsening. Of patients with consistent summer and winter ratings (n = 73), 37% showed high global seasonality scores (GSS) > or = 10. About half this group reported symptoms indicative of major depressive disorder, which was strongly associated with high seasonality. Hierarchical cluster analysis of wintertime symptoms revealed 2 distinct clinical profiles among CFS patients: (a) those with high seasonality, for whom depressed mood clustered with atypical neurovegetative symptoms of hypersomnia and hyperphagia, as is seen in SAD; and (b) those with low seasonality, who showed a primary clustering of classic CFS symptoms (fatigue, aches, cognitive disturbance), with depressed mood most closely associated with irritability, insomnia, and anxiety. It appears that a subgroup of patients with CFS shows seasonal variation in symptoms resembling those of SAD, with winter exacerbation. Light therapy may provide patients with CFS an effective treatment alternative or adjunct to antidepressant drugs.

Adult↗
PubMed1992

The nasal response to histamine challenge: effect of the pollen season and immunotherapy.

To evaluate changes in the nasal response to histamine, we challenged 19 subjects with allergic rhinitis caused by ragweed (RW) before, during, and after the RW season with increasing doses of histamine diphosphate. We compared their response, as measured by symptoms and the levels of TAME-esterase activity and albumin recovered in the nasal lavage fluid, with response of two groups with allergic rhinitis undergoing immunotherapy with moderate-dose (N = 16) and high-dose (N = 11) RW (2 and 24 micrograms of antigen E [Amb a I] as maintenance dose, respectively). Four challenges with histamine were performed in each group: before, at the peak of, near the end of, and 2 weeks after the RW season. The three groups of subjects had similar skin sensitivity to antigen and levels of TAME-esterase activity and albumin recovered from nasal lavages after histamine challenge performed before seasonal exposure. Symptom diaries obtained throughout the season revealed a significant reduction only in the high-dose immunotherapy-treated group. At the peak of the season, the untreated group had more symptoms in response to the challenge compared with the challenges before and after the season (p = 0.04 for both groups). The saline challenge occurring before challenging with histamine also demonstrated a significant increase at the peak of the season compared with increases before the season (p = 0.02). This observation was also true for the levels of albumin and TAME-esterase activity. If the response after saline challenge was subtracted from each response after histamine challenge, no difference was found in the results between any of the visits.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Seasonality and pituitary volume.

Pituitary volume in humans has been reported to change size in response to experimental manipulations of photoperiod, and to be increased during an episode of non-seasonal major depression. We wanted to determine whether pituitary volume changes either across the seasons or during an episode of winter depression. Nineteen patients with winter-seasonal affective disorder and 19 sex-, age-, height-, and weight-matched controls underwent magnetic resonance imaging of the pituitary gland in both winter and summer. Images were obtained using 0.7-mm contiguous slices and the areas of all slices were summed to compute the final volume for each gland. We found no main effects or interactions involving either diagnosis or season in our primary analysis. In a post-hoc analysis, we found a trend towards a season x gender effect (P = 0.06), such that pituitary volume increased slightly (+4.0%) across seasons in women, whereas it decreased slightly (-4.3%) across seasons in men. The results suggest that neither winter depression nor the change of seasons is associated with a significant change in pituitary size.

Age Factors↗
PubMed1998

Seasonal patterns of deaths in Matlab, Bangladesh.

BACKGROUND: Deaths exhibit a seasonal pattern in most parts of the world. Analyses of deaths for the years 1972-1974 from the vital registration system of Matlab, Bangladesh, published in this journal 17 years ago, showed sinusoidal seasonal patterns. As death rates have declined in other nations, the seasonal pattern is attenuated. Death rates have declined substantially in Bangladesh in the past two decades. Thus, the present study examines monthly counts of deaths from Matlab data for a period 15 years later and tests the hypothesis of a decrease or shift in seasonality over time. METHODS: Trigonometric regression models were fit to monthly data by age and cause of death from the Matlab vital registration system for the years 1982-1990. A total of 20,328 death records were available for analyses. RESULTS: In the recent period significant sinusoidal seasonal patterns are found in all but one of the age and cause of death groups. Total deaths peak in the winter as do neonatal deaths but post-neonatal and child deaths are maximum in April and July respectively. Among cause groups, injury deaths (mostly attributed to drowning) show the greatest seasonal swing. The time of peak has only shifted for one age group--neonates--since the 1972-1974 period. The magnitude of the seasonal swing has declined significantly only for the neonatal age group and injury cause of death group. CONCLUSION: Marked seasonal patterns of deaths persist in the Matlab area of Bangladesh even as the level of mortality has declined.

Adolescent↗
PubMed1997

Seasonality and malaria in a west African village: does high parasite density predict fever incidence?

In this cohort study, the authors studied the effect of blood malaria parasite density on fever incidence in children in an endemic area with 9 days' follow-up of 1- to 12-year-old children during two time periods: the end of the dry season (May 1993: n = 783) and the end of the rainy season (October 1993: n = 841) in Bougoula, West Africa (region of Sikasso, Mali). The cumulative incidence of fever (temperature > 38.0 degrees C) was 2.0% in the dry season and 8.2% in the rainy season (p < 0.0001). In the rainy season, the risk of fever was increased in children of ages 1-3 years (relative risk (RR) = 2.5, 95% confidence interval (CI) 1.6-4.1); in those with an initial parasitemia > 15,000/microliter (RR = 2.7, 95% CI 1.4-5.4); in children with an enlarged spleen (RR = 2.0, 95% CI 1.2-3.3); or in those with anemia (hematocrit < 30%: RR = 1.8, 95% CI 1.1-2.9). In the dry season, anemia was the only predictor of fever incidence. In the rainy season, the best predictors of fever were, in order, age (< 4 years), enlarged spleen, and high parasite density. Even in the higher risk groups, the cumulative incidence was < 20%. The authors conclude that most children with high parasite density do not develop fever subsequently. The association between parasite density and fever varies according to age and season. Since even high levels of parasite density do not reliably predict fever incidence, parasite density should be considered as just one of a group of indicators that increase the probability of a fever of malarial origin.

Africa, Western↗
PubMed1997

Effect of immunotherapy on seasonal changes in serum-specific IgE and IgG4 in patients with pollen allergic rhinitis.

Serum specific IgE and IgG4 in 70 patients with seasonal rhinitis caused by Japanese cedar pollens were determined before and during the pollen season. Seasonal increase rate in specific IgE was significantly smaller in the immunotherapy patients than the pharmacotherapy patients, and seasonal increase in specific IgG4 was significant in the immunotherapy patients only. Seasonal increase rate in specific IgE was not significantly different between the patients who responded markedly to short-term immunotherapy and those who did not. On the other hand, seasonal increase rate in specific IgG4 was significantly different between them. In contrast, seasonal increase rate in specific IgE was significantly smaller in the patients who showed marked response to the long-term immunotherapy than those who did not show marked response to the long-term immunotherapy, but seasonal increase rate in specific IgG4 was not significantly different between them. In conclusion, our results suggest that modulation of specific IgG4 response and specific IgE response might be involved in the early and late symptom relief during immunotherapy, respectively. However, further studies might be necessary to definitively establish the clinical roles of specific IgE and specific IgG4 in immunotherapy.

Adolescent↗
PubMed1984

Seasonal variation of asthma and allergic rhinitis. Consultation pattern in general practice related to pollen and spore counts and to five indicators of air pollution.

The seasonal variation of consultations on account of asthma and allergic rhinitis, and the relationship with air concentrations of pollen, spores, and lead, cadmium, dust, soot and sulfur dioxide was investigated in Danish general practice during a 1-year period 1977-78. A population of about 500,000 was studied. Among about 3000 asthmatics there were less consultations during spring than the rest of the year, but the seasonal variation of consultations with symptoms was rather small. The highest rate of consultations was in week 24, which is close to the peak of the grass pollen period. No relationship was found between asthma symptoms and concentrations of pollution indicators. Among about 5000 patients with allergic rhinitis the rate of consultations with symptoms increased at the start of the tree pollen season, still more at the start of the birch pollen season, and was very high during weeks 21-26 in the grass pollen season. Two thirds of all consultations for symptomatic allergic rhinitis took place within 10 weeks (Nos. 18-27). During the grass pollen season there was a relative preponderance of young patients, while during the birch pollen season older patients dominated. No connection was seen between rhinitis symptoms and pollution indicators. The different seasonal variation of asthma and allergic rhinitis indicates that the two patient categories differ as regards symptom-provoking factors. Allergic rhinitis is mainly precipitated by grass and birch pollen. The precipitating factors of asthma were not disclosed in this study, with the exception perhaps of some influence from pollen, and - among 0-4-year-old children - respiratory infections.

Asthma↗
PubMed2006

Seasonal changes of proapoptotic soluble Fas ligand level in allergic rhinitis combined with asthma.

The function of apoptosis is to eliminate unnecessary or dangerous cells. The balance between production and death is important in the control of cell numbers within physiological ranges. Cells involved in allergic reactions may have altered apoptosis. The aim of this study was to examine the seasonal changes of programmed cell death in children with pollen allergy. We measured serum levels of soluble Fas (sFas) and soluble Fas ligand (sFasL), and examined whether there was any correlation between soluble apoptosis markers and development of asthma and or rhinitis in children with pollen allergy. We examined two groups of patients with ragweed pollen allergy. The first group consisted of 17 children with 'rhinitis only'. The second group consisted of 16 children with 'asthma + rhinitis'. For seasonal analysis we pooled the two groups and termed this the 'ragweed sensitive' group (n = 33, 5-18 yr, 25 boys, eight girls). Measurements (sFas and sFasL) were taken during the ragweed pollen allergy season, while control measurements were performed during the symptom-free period. There was no difference in sFas levels measured during and after [1941 +/- 68, 1963 +/- 83 pg/ml (mean+/-s.e.m, respectively)] the pollen season in the 'ragweed sensitive' group. The sFasL level showed seasonal change, which was significantly higher (p = 0.0086) in the symptomatic period compared to the symptom-free state (99 +/- 13 and 53 +/- 16 pg/ml, respectively). There was a difference between the 'rhinitis only' and the 'asthma + rhinitis' groups in the measured parameters of apoptosis. Children having allergic rhinitis combined with asthma had a significantly (p = 0.03) higher sFas level in the symptom-free state than the 'rhinitis only' group did (2115 +/- 156 and 1820 +/- 52 pg/ml, respectively). During the allergic symptom state the sFasL level of the 'asthma + rhinitis' group was significantly higher (p = 0.025) than that of the 'rhinitis only' group (125 +/- 20 and 75 +/- 14 pg/ml, respectively). In conclusion, the increased level of sFasL during the pollen season may signal its role in the pathogenesis of allergic airway diseases. There was no seasonal change in sFas levels in the examined ragweed allergic group, however in the symptomatic period we observed a diminished level of antiapoptotic factor (sFas) and an elevated level of proapoptotic factor (sFasL) if there was a combined disease with pollen allergic asthma. We suggest that there is a deviation in the apoptotic reaction in children that may increase the seasonal allergic inflammation.

Ambrosia↗
PubMed1992

Seasonal patterns of bulimia nervosa.

OBJECTIVE: The aim of this research was to determine whether a seasonal pattern to symptoms of bulimia nervosa could be identified. METHOD: In study 1, seasonal patterns of binge-purge frequency and mood were compared between 31 patients with bulimia nervosa and 31 age-matched normal comparison subjects, using a modified (to include binge and purge items) version of the Seasonal Pattern Assessment Questionnaire. Study 2 involved a cross-sectional examination of binge and purge frequency and of depressive symptoms in 197 patients with bulimia nervosa assessed at various months of the year over a 4-year period. RESULTS: In both the retrospective and cross-sectional studies, binge behavior was found to be highly associated with photoperiod. According to the modified Seasonal Pattern Assessment Questionnaire, purging behavior and mood also varied seasonally among patients with bulimia nervosa. However, purging behavior and severity of depression did not appear to be related to photoperiod in the cross-sectional study. The rate of seasonal affective disorder (syndromal and subsyndromal) defined by the Seasonal Pattern Assessment Questionnaire was higher among the bulimic group than the comparison subjects, but not as high as has been reported for depression in bulimia nervosa. CONCLUSIONS: The results strongly support the interpretation that symptoms of bulimia nervosa primarily associated with food intake patterns are influenced by seasonal variation, and this effect may be mediated by light availability.

Adult↗
PubMed1994

Seasonal variation of neonatal and infant deaths by cause in Greece.

The seasonal variation of neonatal and infant deaths in Greece was analyzed for nine consecutive years (1979-1987) by cause of death, age of death and urbanization of permanent residence. Data were supplied by the National Statistical Service of Greece. Statistical analysis was done using the Edward's method. The seasonal patterns of the number of deaths and death rates were similar. Neonatal deaths in total did not show significant seasonality but postneonatal deaths showed seasonal variation with a peak in the winter, more evident in rural areas. Neonatal deaths from prematurity showed statistically significant seasonal variation with a peak in May. Postneonatal deaths from infections and mainly those from pneumonia showed very significant seasonal variation with a peak in February that was more prominent in rural areas. Seasonal pattern with peak in late winter was also found for postneonatal deaths from injuries. The seasonal patterns for neonatal and postneonatal deaths from sudden infant death syndrome were suggestive of an increased occurrence during the winter months mainly in urban areas.

Age Factors↗
PubMed2000

Preventive symptomatic immunotherapy versus placebo in seasonal rhinitis due to grasses in children and to Parietaria in adult patients.

BACKGROUND: EPD is the only preventive symptomatic immunotherapy available on the market and approved by competent bodies. Recent double-blind placebo controlled (DBPC) studies have demonstrated its efficacy in seasonal and perennial rhinitis. The aim of the study was to confirm the efficacy and safety of a single dose of immunotherapy administered six-eight weeks before the pollen season. METHODS: Two simultaneous DBPC trials were carried out. The first consisted of 20 children with grass-pollen seasonal rhinitis (Bollate-Milano, Italy) and the second included 30 adult patients with Parietaria-pollen seasonal rhinitis (Genova, Italy). EPD was administered only to the active groups. RESULTS: A significant difference in favour of the active treatment groups was seen in oral antihistamine use (p < 0.05) during the peak pollen seasons. Throughout the pollen seasons, rhinoconjunctivitis scores for the two groups in both studies presented no significant difference, even if the values were lower in the active groups. CONCLUSIONS: The oral antihistamine reduction, observed in the active groups during the seasonal period, supports the efficacy of this treatment, although a significant improvement in the rhinoconjunctivitis symptoms was not observed, probably due to the use of oral antihistamine in the placebo groups. The overall profile of the EPD was good. It could be particularly suited for short term therapy to prevent seasonal symptoms in allergic patients.

Adult↗
PubMed2001

Serum soluble tumor necrosis factor receptor levels in patients with seasonal allergic rhinitis.

It is known that several inflammatory cells and cytokines play a role in allergic inflammation. Furthermore, there are seasonal changes in several mediators responsible for allergic inflammation. The aim of this study was to determine seasonal changes in serum concentrations of soluble tumor necrosis factor receptors (sTNFRs) and the relationship with disease activity and other inflammation markers such as eosinophil cationic protein (ECP) in patients with seasonal allergic rhinitis. Serum levels of sTNFRI and sTNFRII were measured before and during the pollen season in 18 patients with seasonal allergic rhinitis and in 17 healthy controls by using commercially available enzyme-linked immunosorbent assay (ELISA) kits. The serum levels of sTNFRI, sTNFRII, IgE, and ECP were significantly higher in patients than those in controls before and during season. sTNFRI, sTNFRII, and IgE levels were higher before season, whereas ECP levels were higher during season. We suggest that sTNFRs might play regulatory roles even in early stages of allergic rhinitis when patients do not have clinical symptoms yet.

Adolescent↗
PubMed2004

[Evaluation of quality of life (QOL) and efficacy of drug therapy on nasal symptoms and QOL disturbances in the patients with Japanese Cedar Pollinosis during the season of 2003 in Kyushu and Okinawa districts].

AIM: The aim of the study is to investigate nasal symptom severity (NSS) and disturbance of quality of life (QOLD) of patients with Japanese Cedar Pollinosis (JCP) during the JC season of 2003, and to evaluate the efficacy of drug treatment on the NSS/QOLD by the data based on disease specific Japan Rhino-conjunctivitis Quality of Life Questionnaire (JRQLQ). SUBJECTS, METHODS AND RESULTS: 3173 patients with JCP from 149 clinics of 8 prefectures in Kyushu and Okinawa districts were subjected. Degree of NSS/QOLD was scored as 1 to 4 in order (1 for a little and 4 for extremely severe or bothered respectively). (1) About 23% of 3173 subjects analyzed complained NSS score > or =3 and about 64% score > or =2. About 10% complained QOLD score > or =3 and about 20-30% score > or =2. (2) Preventive effect of pre-seasonal medication was analyzed. We evaluated the data from 583 patients (177 : received pre-seasonal medication and 406 : not received) who first answered questionnaire before peak of pollen dispersion as the effects on rising-up of symptoms in early stage of pollen scattering, and the data from 1223 patients (431 : received pre-seasonal medication and 792 : not received) who answered during the whole season as the effects on symptoms in whole season. The results of the both analyses indicated that the pre-seasonal medication significantly reduced NSS/QOLD in early stage of pollen scattering as well as during whole season as a preventive effect. (3) Effect of drugs prescribed at the first reply to the questionnaire was analyzed in 582 patients who answered the questionnaire twice before and after the peak of JC pollen scattering (February 28th), with at least 7 days intervals between 2 answers. When a proper designate of prescribed drug was not specified, results of second answer from 582 patients showed significant reduction of NSS/ QOLD score (p<0.001). (4) Single drug which effect was able to be evaluated was anti-allergic drug (mainly second generation of anti histamine: aH) in 81 cases, or anti-leukotriene (aLT) in 25 cases. Although the both drugs were effective, the comparison analysis of effectiveness of 2 drugs indicated that effect of aLT on reduction of NSS/QOLD score was higher than that of aH. Effect of combination drug treatment was able to be evaluated in aH + topical steroids (tS) in 95 cases, aLT + tS in 12 cases and aH + aLT in 25 cases. Those 3 ways of combination were effective, especially the combination with topical steroids with either aH or aLT showed significant higher effect on reduction of NSS/QOLD. CONCLUSION: JRQLQ is useful questionnaire for general clinic to evaluate the QOL disturbances induced by JCP and to follow clinical process relating to QOL changes including effect of drug treatment.

Adolescent↗
PubMed2002

Patients with seasonal affective disorder have lower odor detection thresholds than control subjects.

BACKGROUND: Behavioral changes in patients with seasonal affective disorder resemble seasonal changes in photoperiodic animals. Because the olfactory system has a modulatory role in seasonal photoperiodic responses in certain species, we hypothesized that olfactory function may differ between patients with seasonal affective disorder and healthy control subjects. METHODS: Fourteen patients who had winter seasonal affective disorder and 16 healthy volunteers were studied once in winter and once in the subsequent summer. We administered a phenyl ethyl alcohol detection threshold test to each side of the nose in a counterbalanced order, with the nostril contralateral to the tested site occluded. Patient and control data were compared using a 4-way repeated measure analysis of covariance (with group and gender as between-subjects factors, season and side-of-the-nose as within-subjects factors, and age as a covariate). RESULTS: The patients exhibited lower thresholds than did the controls (F(1,25) = 9.2; P =.006). There was no main effect of season. CONCLUSION: In humans, marked seasonal behavioral rhythms with recurrent winter depression may be associated with a more acute sense of smell.

Adult↗
PubMed1997

Seasonal variation in activity and diet in a small-bodied folivorous primate, Hapalemur griseus, in southeastern Madagascar.

How small-bodied (500-1,200 g) folivorous prosimian primates cope with large amounts of foliage in their diet seasonally has yet to be determined for many species such as Hapalemur griseus, which specializes on bamboo. To address this issue, we present results on seasonal variation in activity and diet from a wild group of H. griseus in southeastern Madagascar. Throughout the study (which was conducted from July-November 1994 and July 1995-February 1996), H. griseus primarily fed on new growth from three species of bamboo: two species of liana bamboo and Cephalostachyum perrieri. Bamboo species were used in different ways seasonally; liana bamboo was consumed more during the dry, cool season, and C. perrieri was eaten more often during the wet, warm season. H. griseus also spent more of their time feeding and traveling than nocturnal folivores of similar body size during the dry season. During the warm wet season, H. griseus decreased the amount of time spent feeding and traveling and rested more often. We hypothesize that seasonal changes in activity may be primarily related to the distribution and availability of food sources and/or reproductive cycles.

Animals↗
PubMed2006

Blood pressure, seasonal body fat, heart rate, and ecological differences in Caboclo populations of the Brazilian Amazon.

This study compares blood pressure (BP) and related cardiovascular risk factors among three Caboclo communities from the Brazilian Amazon. Its purpose is to investigate possible risk differentials related to variable ecological settings and Western influences. Caxiuanã is characterized as a more "traditional" group, while Aracampina and Santana are viewed as more "transitional" in lifestyle. A total of 348 subjects from the three communities were evaluated in the wet or the dry season or in both. Measurements across the communities were compared by season and sex. Results suggest little seasonal variation in average BP, BP change, body fat, or body fat change among men. Conversely, there is substantial seasonal and inter-community variation among women. Additional analyses reveal (1) an inconsistent association between age and BP across the communities; (2) that BMI is not associated with BP transitional communities in either season but is associated with both systolic and diastolic pressure in the most traditional community; and (3) little to no sex effect on BP. These results suggest increased Western influence affects body composition particularly of women. However, increased BMI and fat among transitional Caboclo women does not directly translate into higher BP; rather, their BP appears to be more affected by seasonal stresses. Finally, conditions during the wet season diminish age-related variation in BP, suggesting that during the wet season these Caboclo may be less active.

Adipose Tissue↗
PubMedDate not supplied

Seasonal changes in steroidogenesis in the testis of the rhesus monkey (Macaca mulatta).

To investigate the influence of seasonal changes from breeding to nonbreeding season on testicular steroidogenesis in the adult rhesus monkey, two animals were hemiorchidectomized in November and the second testis of each was removed the following April. Intratesticular steroid concentrations related to the formation of testosterone from pregnenolone were measured by radioimmunoassay. Related steroidogenic enzyme activities were also assayed and dynamic studies of the bioconversion of radiolabeled precursor steroids by testicular microsomes were performed. Testosterone was synthesized from pregnenolone through both dehydroepiandrosterone and 17 alpha-hydroxyprogesterone. No distinct differences were found in the testosterone biosynthetic pathway between testes in breeding and nonbreeding seasons. In the breeding season, intratesticular testosterone concentrations, the sum of intratesticular steroids measured, and the ratio of testosterone to the steroid sum were increased when compared to those in the nonbreeding season. No major seasonal changes in microsome enzyme activities were found, although enzyme activities, except for delta 5-3 beta-hydroxysteroid dehydrogenase for C21-steroids, were slightly higher in the breeding season. We conclude that increased testosterone production in the testis during the breeding season is due primarily to increased pregnenolone supply from Leydig cell mitochondria and, to a lesser extent, to an enhanced pregnenolone bioconversion to testosterone in the microsomes.

3-Hydroxysteroid Dehydrogenases↗